text:
Hesse

Hesse or Hessia (Hessen ), officially the State of Hesse (Land Hessen), is a state in Germany. Its capital city is Wiesbaden, and the largest urban area is Frankfurt, which is also the country's principal financial centre. Two other major historic cities are Darmstadt and Kassel. With an area of 21,114.73 square kilometers and a population of over six million, it ranks seventh and fifth, respectively, among the sixteen German states. Frankfurt Rhine-Main, Germany's second-largest metropolitan area (after Rhine-Ruhr), is mainly located in Hesse.

As a cultural region, Hesse also includes the area known as Rhenish Hesse (Rheinhessen) in the neighbouring state of Rhineland-Palatinate.

Etymology
The German name Hessen, like the names of other German regions (Schwaben "Swabia", Franken "Franconia", Bayern "Bavaria", Sachsen "Saxony"), derives from the dative plural form of the name of the inhabitants or eponymous tribe, the Hessians (Hessen, singular Hesse). The geographical name represents a short equivalent of the older compound name Hessenland ("land of the Hessians"). The Old High German form of the name is recorded as Hessun (dative plural of Hessi); in Middle Latin it appears as Hassonia, Hassia, Hessia. The name of the Hessians ultimately continues the tribal name of the Chatti. The ancient name Chatti by the 7th century is recorded as Chassi, and from the 8th century as Hassi or Hessi.

An inhabitant of Hesse is called a "Hessian" (German: Hesse (masculine), plural Hessen, or Hessin (feminine), plural Hessinnen). The American English term "Hessian" for 18th-century British auxiliary troops originates with Landgrave Frederick II of Hesse-Kassel hiring out regular army units to the government of Great Britain to fight in the American Revolutionary War.

The English form Hesse was in common use by the 18th century, first in the hyphenated names of the states of Hesse-Cassel and Hesse-Darmstadt, but the latinate form Hessia remained in common English usage well into the 19th century.

The European Commission uses the German form Hessen, even in English-language contexts, due to the policy of leaving regional names untranslated.

The synthetic element hassium, number 108 on the periodic table, was named after the state of Hesse in 1997, following a proposal of 1992.

History
The territory of Hesse was delineated only in 1945, as Greater Hesse, under American occupation. It corresponds loosely to the medieval Landgraviate of Hesse. In the 19th century, prior to the unification of Germany, the territory of what is now Hesse comprised the territories of Grand Duchy of Hesse (also known as Hesse-Darmstadt), the Duchy of Nassau, the free city of Frankfurt and the Electorate of Hesse (also known as Hesse-Kassel).

Early history
The Central Hessian region was inhabited in the Upper Paleolithic. Finds of tools in southern Hesse in Rüsselsheim suggest the presence of Pleistocene hunters about 13,000 years ago. A fossil hominid skull that was found in northern Hesse, just outside the village of Rhünda, has been dated at 12,000 years ago. The Züschen tomb (German: Steinkammergrab von Züschen, sometimes also Lohne-Züschen) is a prehistoric burial monument, located between Lohne and Züschen, near Fritzlar, Hesse, Germany. Classified as a gallery grave or a Hessian-Westphalian stone cist (hessisch-westfälische Steinkiste), it is one of the most important megalithic monuments in Central Europe. Dating to c. 3000 BC, it belongs to the Late Neolithic Wartberg culture.

An early Celtic presence in what is now Hesse is indicated by a mid-5th-century BC La Tène-style burial uncovered at Glauberg. The region was later settled by the Germanic Chatti tribe around the 1st century BC, and the name Hesse is a continuation of that tribal name.

The ancient Romans had a military camp in Dorlar, and in Waldgirmes directly on the eastern outskirts of Wetzlar was a civil settlement under construction. Presumably, the provincial government for the occupied territories of the right bank of Germania was planned at this location. The governor of Germania, at least temporarily, likely had resided here. The settlement appears to have been abandoned by the Romans after the devastating Battle of the Teutoburg Forest failed in the year AD 9. The Chatti were also involved in the Revolt of the Batavi in AD 69.

Hessia, from the early 7th century on, served as a buffer between areas dominated by the Saxons (to the north) and the Franks, who brought the area to the south under their control in the early sixth century and occupied Thuringia (to the east) in 531. Hessia occupies the northwestern part of the modern German state of Hesse; its borders were not clearly delineated. Its geographic center is Fritzlar; it extends in the southeast to Hersfeld on the river Fulda, in the north to past Kassel and up to the rivers Diemel and Weser. To the west, it occupies the valleys of the rivers Eder and Lahn (the latter until it turns south). It measured roughly 90 kilometers north–south, and 80 north-west.

The area around Fritzlar shows evidence of significant pagan belief from the 1st century on. Geismar was a particular focus of such activity; it was continuously occupied from the Roman period on, with a settlement from the Roman period, which itself had a predecessor from the 5th century BC. Excavations have produced a horse burial and bronze artifacts. A possible religious cult may have centered on a natural spring in Geismar, called Heilgenbron; the name "Geismar" (possibly "energetic pool") itself may be derived from that spring. The village of, now a part of Gudensberg near Fritzlar and less than ten miles from Geismar, was likely an ancient religious center; the basaltic outcrop of Gudensberg is named after Wodan, and a two-meter tall quartzite megalith called the Wotanstein is at the center of the village.

By the mid-7th century, the Franks had established themselves as overlords, which is suggested by archeological evidence of burials, and they built fortifications in various places, including Christenberg. By 690, they took direct control over Hessia, apparently to counteract expansion by the Saxons, who built fortifications in Gaulskopf and Eresburg across the river Diemel, the northern boundary of Hessia. The Büraburg (which already had a Frankish settlement in the sixth century ) was one of the places the Franks fortified to resist the Saxon pressure, and according to John-Henry Clay, the Büraburg was "probably the largest man-made construction seen in Hessia for at least seven hundred years". Walls and trenches totaling one kilometer in length were made, and they enclosed "8 hectares of a spur that offered a commanding view over Fritzlar and the densely-populated heart of Hessia".

Following Saxon incursions into Chattish territory in the 7th century, two gaue had been established; a Frankish one, comprising an area around Fritzlar and Kassel, and a Saxonian one. In the 9th century, the Saxon Hessengau also came under the rule of the Franconians.

Holy Roman Empire
From 962 the land which would become Hesse was part of the Holy Roman Empire. In the 10th and 11th centuries it was mostly encompassed by the Western or Rhenish part of the stem duchy of Franconia.

In the 12th century, Hessengau passed to the Landgraviate of Thuringia. As a result of the War of the Thuringian Succession (1247–1264) the former Thuringian lands were partitioned between the Wettin Margraviate of Meissen, which gained Thuringia proper, and the new Landgraviate of Hesse, which remained with the Ludovingians. From that point on the Ludovingian coat of arms came to represent both Thuringia and Hesse.

It rose to prominence under Landgrave Philip the Magnanimous, who was one of the leaders of German Protestantism. After Philip's death in 1567, the territory was divided among his four sons from his first marriage (Philip was a bigamist) into four lines: Hesse-Kassel (or Hesse-Cassel), Hesse-Darmstadt, Hesse-Rheinfels, and the also previously existing Hesse-Marburg. As the latter two lines died out quite quickly (1583 and 1605, respectively), Hesse-Kassel and Hesse-Darmstadt were the two core states within the Hessian lands. Several collateral lines split off during the centuries, such as in 1622, when Hesse-Homburg split off from Hesse-Darmstadt, and in 1760 when Hesse-Hanau split off from Hesse-Kassel. In the late 16th century, Kassel adopted Calvinism, while Darmstadt remained Lutheran and consequently the two lines often found themselves on opposing sides of conflicts, most notably in the disputes over Hesse-Marburg and in the Thirty Years' War, when Darmstadt fought on the side of the Emperor, while Kassel sided with Sweden and France.

The Landgrave Frederick II (1720–1785) ruled Hesse-Kassel as a benevolent despot, from 1760 to 1785. He combined Enlightenment ideas with Christian values, cameralist plans for central control of the economy, and a militaristic approach toward diplomacy. He funded the depleted treasury of the poor government by loaning 19,000 soldiers in complete military formations to Great Britain to fight in North America during the American Revolutionary War, 1776–1783. These soldiers, commonly known as Hessians, fought under the British flag. The British used the Hessians in several conflicts, including in the Irish Rebellion of 1798. For further revenue, the soldiers were loaned to other places as well. Most were conscripted, with their pay going to the Landgrave.

French Revolution and Napoleonic Wars
In 1789 the French Revolution began and in 1794, during the War of the First Coalition, the French Republic occupied the Left Bank of the Rhine, including part of Lower Katzenelnbogen (Niedergrafschaft Katzenelnbogen, Hesse-Kassel's part of the former County of Katzenelnbogen which was held by the appanage Hesse-Rotenburg). Emperor Francis II formally recognised the annexation of the Left Bank in the 1801 Treaty of Lunéville. This led in 1803 to the Reichsdeputationshauptschluss, a substantial reorganisation (mediatisation) of the states and territories of the Empire. Several exclaves of Mainz were mediatised to Hesse-Kassel and Hesse-Darmstadt, and Hesse-Darmstadt also gained the Duchy of Westphalia from Cologne, the parts of Worms on the right-bank of the Rhine, and the former Free City of Friedberg. Nassau-Weilburg gained the right-bank territories of Trier among other territories. Orange-Nassau gained the Prince-Bishopric of Fulda (as the Principality of Nassau-Orange-Fulda). The Landgrave of Hesse-Kassel was also elevated to the status of Prince-Elector (Kurfürst), with his state thereby becoming the Electorate of Hesse or Electoral Hesse (Kurhessen, Kur being the German-language term for the Empire's College of Electors).

In July 1806 Hesse-Darmstadt, Nassau-Weilburg, Nassau-Usingen, and the newly merged Principality of Isenburg became founding members of Napoleon's Confederation of the Rhine. Hesse-Darmstadt expanded further in the resulting mediatisation, absorbing numerous small states (including Hesse-Homburg and much of the territory of the Houses of House of Solms, House of Erbach and Sayn-Wittgenstein). It was also elevated by Napoleon to the status of Grand Duchy, becoming the Grand Duchy of Hesse. Orange-Nassau, which refused to join the Confederation, lost Siegen, Dillenburg, Hadamar and Beilstein to Berg and Fulda to the Prince-Primate of the Confederation (and former Elector of Mainz) Karl Theodor von Dalberg; the remainder of its territory was merged with that of Nassau-Usingen and Nassau-Weilburg in August 1806 to form the Duchy of Nassau. Waldeck also joined the Confederation in 1807.

The Holy Roman Empire was dissolved in August 1806, rendering Hesse-Kassel's electoral privilege meaningless. Hesse-Kassel was occupied by the French in October 1806 and the remainder of Lower Katzenelnbogen was annexed to the French Empire as Pays réservé de Catzenellenbogen. The rest of its territory was annexed to the Kingdom of Westphalia in 1807; Hesse-Hanau (a secundogeniture of Hesse-Kassel) was annexed to the Grand Duchy of Frankfurt in 1810 along with the other territories held by the Prince-primate: Frankfurt, Fulda, Aschaffenburg and Wetzlar.

As a result of the German campaign of 1813 the Kingdom of Westphalia and the Grand Duchy of Frankfurt were dissolved and Hesse-Kassel and Hesse-Hanau were restored; Orange-Nassau was also restored in its territories previously lost to Berg.

As a result of the 1815 Congress of Vienna Hesse-Kassel gained Fulda (roughly the western third of the former Prince-Bishopric, the rest of which went to Bavaria and Saxe-Weimar-Eisenach) from Frankfurt and part of Isenburg, while several of its small northern exclaves were absorbed into Hanover, some small eastern areas were ceded to Saxe-Weimar-Eisenach and Lower Katzenelnbogen was ceded to Nassau. Hesse-Darmstadt lost the Duchy of Westphalia and the Sayn-Wittgensteiner lands to the Prussian Province of Westphalia but gained territory on the left bank of the Rhine centred on Mainz, which became known as Rhenish Hesse (Rheinhessen), and the remainder of Isenburg. Orange-Nassau, whose ruler was now also King William I of the Netherlands and Grand Duke of Luxembourg, was ceded to Prussia but most of its territory aside from Siegen was then ceded on to Nassau. Hesse-Homburg and the Free City of Frankfurt were also restored.

While the other former Electors had gained other titles, becoming either Kings or Grand Dukes, the Elector of Hesse-Kassel alone retained the anachronistic title of Prince-Elector; a request to be recognised as "King of the Chatti" (König der Katten) was rejected by the Congress.

Following the mediatisations and the Congress of Vienna significantly fewer states remained in the region that is now Hesse: the Hessian states, Nassau, Waldeck and Frankfurt. The Kingdoms of Prussia and Bavaria also held some territory in the region. The Congress also established the German Confederation, of which they all became members. Hesse-Hanau was (re-)absorbed into Hesse-Kassel in 1821.

German Empire
In the 1866 Austro-Prussian War the states of the region allied with Austria were defeated during the Campaign of the Main. Following Prussia's victory and dissolution of the German Confederation, Prussia annexed Electoral Hesse, Frankfurt, Hesse-Homburg, Nassau and small parts of Bavaria and the Grand Duchy of Hesse, which were then combined into the Province of Hesse-Nassau. The name Kurhessen survived, denoting the region around Kassel. The Grand Duchy of Hesse retained its autonomy in defeat because a greater part of the country was situated south of the river Main and it was feared that Prussian expansion beyond the Main might provoke France. However, Upper Hesse (Oberhessen: the parts of Hesse-Darmstadt north of the Main around the town of Gießen) was incorporated into the North German Confederation (Norddeutscher Bund), a tight federation of German states established by Prussia in 1867, while also remaining part of the Grand Duchy. In 1871, after France's defeat in the Franco-Prussian War, the whole of the Grand Duchy joined the German Empire.

Around the turn of the 20th century, Darmstadt was one of the centres of the Jugendstil. Until 1907, the Grand Duchy of Hesse used the Hessian red and white lion barry as its coat-of-arms.

Weimar and Nazi periods
The revolution of 1918 following the German defeat in WWI transformed Hesse-Darmstadt from a monarchy to a republic, which officially renamed itself the People's State of Hesse (Volksstaat Hessen). The state parliament, or Landtag consisted of 70 deputies elected on the basis of proportional representation. There were six Landtag elections between 1919 and 1932. Following the Nazi seizure of power in Berlin, the Landtag was formally abolished as a result of the "Law on the Reconstruction of the Reich" of 30 January 1934, which replaced the German federal system with a unitary state.

The parts of Hesse-Darmstadt on the left bank of the Rhine (Rhenish Hesse), as well as those right-bank areas of Hesse-Darmstadt and Hesse-Nassau within 30 km of Koblenz or Mainz were occupied by French troops until 1930 under the terms of the Versailles peace treaty that officially ended World War I in 1919. The Kingdom of Prussia became the Free State of Prussia, of which Hesse-Nassau remained a province.

In 1929 the Free State of Waldeck was dissolved and incorporated into Hesse-Nassau. In 1932 Wetzlar (Landkreis Wetzlar), formerly an exclave of the Prussian Rhine Province situated between Hesse-Nassau and the Grand Duchy's Upper Hesse, was transferred to Hesse-Nassau. The former Hessian exclave of Rinteln (Landkreis Grafschaft Schaumburg, the Hessian part of the former County of Schaumburg) was also detached and transferred to the Province of Hanover.

On 1 July 1944 the Prussian Province of Hesse-Nassau was formally divided into the provinces of Kurhessen and Nassau. At the same time the former Hessian Schmalkalden exclaves (Landkreis Herrschaft Schmalkalden), together with the Regierungsbezirk Erfurt of the Province of Saxony, were transferred to Thuringia. The territories of the new provinces did not directly correspond with their pre-1866 namesakes but rather with the associated NSDAP Gaue: Gau Electoral Hesse and Gau Hesse-Nassau (excluding the areas which were part of the People's State of Hesse).

Post-World War II
After World War II, the Hessian territory west of the Rhine was again occupied by France, while the rest of the region was part of the US occupation zone. On 17 September 1945 the Wanfried agreement adjusted the border between American-occupied Kurhessen and Soviet-occupied Thuringia. The United States proclaimed the state of Greater Hesse (Groß-Hessen) on 19 September 1945, out of the People's State of Hesse and most of what had been the Prussian Provinces of Kurhessen and Nassau. The French incorporated their parts of Hesse (Rhenish Hesse) and Nassau (as Regierungsbezirk Montabaur) into the newly founded state of Rhineland-Palatinate (Rheinland-Pfalz) on 30 August 1946.

On 4 December 1946, Greater Hesse was officially renamed Hessen. Hesse in the 1940s received more than a million displaced ethnic Germans.

Due to its proximity to the Inner German border, Hesse became an important location of NATO installations in the 1950s, especially military bases of the US V Corps and United States Army Europe.

The first elected minister president of Hesse was Christian Stock, followed by Georg-August Zinn (both Social Democrats). The German Social Democrats gained an absolute majority in 1962 and pursued progressive policies with the so-called Großer Hessenplan. The CDU gained a relative majority in the 1974 elections, but the Social Democrats continued to govern in a coalition with the FDP. Hesse was first governed by the CDU under Walter Wallmann during 1987–1991, replaced by a SPD-Greens coalition under Hans Eichel during 1991–1999. From 1999, Hesse was governed by the CDU under Roland Koch (retired 2010) and Volker Bouffier (incumbent as of 2020). Frankfurt during the 1960s to 1990s developed into one of the major cities of West Germany. As of 2016, 12% of the total population of Hesse lived in the city of Frankfurt.

Geography

The only state to straddle west and central portions of Germany where the eight ordinal directions (compass points) and the centre is considered, Hesse borders six other states. These are, from north, clockwise: Lower Saxony, Thuringia, Bavaria, Baden-Württemberg, Rhineland-Palatinate, and North Rhine-Westphalia.

The most populous towns and cities of Hesse are in the southwest, the Frankfurt Rhein-Main Region namely Frankfurt am Main, Wiesbaden, Darmstadt, Offenbach, Hanau, Giessen, Wetzlar, and Rüsselsheim am Main. Outside, but very near the south-west corner of Hesse are four populous, highly technologised, places: Worms, Ludwigshafen, Mannheim, and Heidelberg.

Other large Hessian towns are Fulda in the east, Kassel and Marburg an der Lahn in the north and Limburg an der Lahn in the west. All of the "on the river" suffixes are locally and, informally far beyond, omitted of these cities. The plain between the rivers Main, Rhine, and lower Neckar, and the Odenwald ridge of low mountains or very high hills is called the Ried which continues to north, across the Main, as the Wetterau. Both plains which are quite densely populated also have a substantial built environment such as the country's largest airport, contrasting with the more forested, hillier middle and northern thirds of Hesse.

The longest rivers in Hesse are the Eder and moreover its distributary the Fulda draining most of the north, the Lahn in the centre-west and, as to those navigable by large vessels, the Main and very broad Rhine in the south. The countryside is hilly and the topographical map, inset, names 14 short, low to medium-height mountain ranges including the Rhön, the Westerwald, the Taunus, the Vogelsberg, the Knüll and the Spessart. The notable range forming the southern taper of Hesse (shared with a narrowing of the Ried, the Rhine's eastern plain) and briefly spanning the middle Neckar valley which begins directly east of Heidelberg (thus also in Baden-Württemberg) is the Odenwald. Forming a mid-eastern tiny projection into mostly Thuringia is the uppermost part of the Ulster, commanding the west valley side of which is the Hessian highest point, Wasserkuppe at 950m above sea level – in the Rhön.

The Rhine forms the long southwest border of Hesse. Two notables oxbow lakes, the Stockstadt-Erfelder Altrhein and Lampertheimer Altrhein are in the south-west fringe.

Hesse, 42% forest, is by that measure the greenest state in Germany.

Administration
Hesse is a unitary state governed directly by the Hessian government in the capital city Wiesbaden, partially through regional vicarious authorities called Regierungspräsidien. Municipal parliaments are, however, elected independently from the state government by the Hessian people. Local municipalities enjoy a considerable degree of home rule.

Districts
The state is divided into three administrative provinces (Regierungsbezirke): Kassel in the north and east, Gießen in the centre, and Darmstadt in the south, the latter being the most populous region with the Frankfurt Rhine-Main agglomeration in its central area. The administrative regions have no legislature of their own, but are executive agencies of the state government.

Hesse is divided into 21 districts (Kreise) and five independent cities, each with their own local governments. They are, shown with abbreviations as used on vehicle number plates:

 * 1) Bergstraße (Heppenheim) (HP)
 * 2) Darmstadt-Dieburg (Darmstadt) (DA, DI)
 * 3) Groß-Gerau (Groß-Gerau) (GG)
 * 4) Hochtaunuskreis (Bad Homburg) (HG, USI)
 * 5) Main-Kinzig-Kreis (Gelnhausen) (MKK, GN, HU, SLÜ)
 * 6) Main-Taunus-Kreis (Hofheim am Taunus) (MTK)
 * 7) Odenwaldkreis (Erbach) (ERB)
 * 8) Offenbach (Dietzenbach) (OF)
 * 9) Rheingau-Taunus-Kreis (Bad Schwalbach) (RÜD, SWA)
 * 10) Wetteraukreis (Friedberg) (FB, BÜD)
 * 11) Gießen (Gießen) (GI)
 * 12) Lahn-Dill-Kreis (Wetzlar) (LDK, DIL, WZ)
 * 13) Limburg-Weilburg (Limburg) (LM, WEL)
 * 14) Marburg-Biedenkopf (Marburg) (MR, BID)
 * 15) Vogelsbergkreis (Lauterbach) (VB)
 * 16) Fulda (Fulda) (FD)
 * 17) Hersfeld-Rotenburg (Bad Hersfeld) (HEF, ROF)
 * 18) Kassel (Kassel) (KS, HOG, WOH)
 * 19) Schwalm-Eder-Kreis (Homberg (Efze)) (HR, ZIG, FZ)
 * 20) Werra-Meißner-Kreis (Eschwege) (ESW, WIZ)
 * 21) Waldeck-Frankenberg (Korbach) (KB, FKB, WA)

Independent cities:
 * 1) Darmstadt (DA)
 * 2) Frankfurt am Main (F)
 * 3) Kassel (KS)
 * 4) Offenbach am Main (OF)
 * 5) Wiesbaden (WI)

Rhenish Hesse
The term "Rhenish Hesse" (Rheinhessen) refers to the part of the former Grand Duchy of Hesse-Darmstadt located west of the Rhine. It has not been part of the State of Hesse since 1946 due to divisions in the aftermath of World War II. This province is now part of the State of Rhineland-Palatinate. It is a hilly countryside largely devoted to vineyards; therefore, it is also called the "land of the thousand hills". Its larger towns include Mainz, Worms, Bingen, Alzey, Nieder-Olm, and Ingelheim. Many inhabitants commute to work in Mainz, Wiesbaden, or Frankfurt.

State symbols and politics
Hesse has been a parliamentary republic since 1918, except during Nazi rule (1933–1945). The German federal system has elements of exclusive federal competences, shared competences, and exclusive competences of the states. Hesse is famous for having a rather brisk style in its politics with the ruling parties being either the center-right Christian Democratic Union (CDU) or the center-left Social Democratic Party of Germany (SPD). Due to the Hessian electoral laws, the biggest party normally needs a smaller coalition partner.

Head of state
As Hesse is a partly sovereign federated state, its constitution combines the offices of the head of state and head of government in one office called the Minister-President (German: Ministerpräsident) which is comparable to the office of a prime minister.

Most recent state election
In the 2018 state elections the two leading parties, CDU and SPD, lost 11.3% (7 seats) and 10.9% (8 seats) of the vote respectively. The Green party, a member of Hesse's previous governing coalition with CDU, gained 8.7% (16 seats). The largest gains during the election were made by Alternative for Germany (AfD) at 13.1%. As AfD had not passed the 5% threshold in the 2013 state election, this marked its first entry into the Hessian parliament (Hessischer Landtag). The two other parties also made gains. The major losses of the two leading parties (whose coalition made up the federal cabinet during the election) closely mirrors the results of the 2018 state elections in Bavaria. In the current parliament the conservative CDU holds 40 seats, the centre-left SPD and the leftist Green party each hold 29 seats, the right-wing AfD holds 19 seats, the liberal FDP party holds 11 seats and the socialist party The Left holds 9 seats.

Foreign affairs
As a member state of the German federation, Hesse does not have a diplomatic service of its own. However, Hesse operates representation offices in such foreign countries as the United States, China, Hungary, Cuba, Russia, Poland, and Iran. These offices are mostly used to represent Hessian interests in cultural and economic affairs. Hesse has also permanent representation offices in Berlin at the federal government of Germany and in Brussels at the institutions of the European Union.

Flag and anthem
The flag colors of Hesse are red and white, which are printed on a Hessian sack. The civil flag of Hesse resembles that of Monaco's and, particularly, Indonesia's. The Hessian coat of arms shows a lion rampant striped with red and white. The official anthem of Hesse is called "Hessenlied" ("Song of Hesse") and was written by Albrecht Brede (music) and Carl Preser (lyrics).

Demographics
Hesse has a population of over 6 million, nearly 4 million of which is concentrated in the Rhein-Main region (German: Rhein-Main Gebiet) in the south of the state, an area that includes the most populous city, Frankfurt am Main, the capital Wiesbaden, and Darmstadt and Offenbach. The population of Hesse is predicted to shrink by 4.3% by 2030, with the biggest falls in the north of the state, especially in the area around the city of Kassel. Frankfurt is the fastest growing city with a predicted rise in population of 4.8% by 2030. Frankfurt's growth is driven by its importance as a financial centre and it receives immigrants from all over the world: in 2015 over half of the city's population had an immigrant background.

Vital statistics
Source:
 * Births January–March 2017 = 14,537
 * Births January–March 2018 = 14,202
 * Deaths January–March 2017 = 19,289
 * Deaths January–March 2018 = 18,831
 * Natural growth January–March 2017 = −4,752
 * Natural growth January–March 2018 = −4,629

Language
Three different languages or dialect groups are spoken in Hesse: The Far North is part of the Low Saxon language area, divided into a tiny Eastphalian and a larger Westphalian dialect area. Most of Hesse belongs to the West Middle German dialect zone. There is some disagreement as to whether all Hessian dialects south of the Benrath line may be subsumed under one dialect group: Rhine Franconian, or whether most dialects should be regarded as a dialect group of its own: Hessian, whereas only South Hessian is part of Rhine Franconian. Hessian proper can be split into Lower Hessian in the north, East Hessian in the East around Fulda and Central Hessian, which covers the largest area of all dialects in Hesse. In the extreme Northeast, the Thuringian dialect zone extends into Hesse, whereas in the Southeast, the state border to Bavaria is not fully identical to the dialect border between East Franconian and East Hessian.

Since approximately World War II, a spoken variety of Standard German with dialect substrate has been superseding the traditional dialects mentioned so far. This development knows a north-to-south movement, the north being early to supplant the traditional language, whereas in the south, there is still a considerable part of the population that communicates in South Hessian. In most of the areas, however, the traditional language is close to extinction, whereas until the first half of the 20th century, almost the entire population spoke dialect in almost all situations. The Upper Class started to speak Standard German beginning in the late 19th century, so for decades, the traditional language served as a sociolect.

The prominent written language in Hesse has been Standard German since the 16th century. Before, the Low Saxon part used Middle Low German, the rest of the Land Early Modern German as prominent written languages. These had supplanted Latin in the High Middle Ages.

Religion

In 2016 Christianity was the most widespread religion in the state (63%). In 2011, 40% of Hessians belonged to the Protestant Church in Hesse and Nassau or Evangelical Church of Hesse Electorate-Waldeck (members of the Protestant Church in Germany), 25% adhered to the Roman Catholic Church, while other Christians constituted some 3%; the next most common religion of the Hessian population was Islam, adhered to by 7%.

Higher education
The Hessian government has overall responsibility for the education within the state. Hesse has follow universities: None of Hesse's universities are included in German Excellence Universities.
 * Goethe University Frankfurt (43,972 students; Budget: €666,4 Mio.)
 * Technical University of Darmstadt (25,355 students; Budget: €482,8 Mio.)
 * Justus Liebig University Giessen (28,480 students; Budget: €425,4 Mio.)
 * Philipps University of Marburg (24,394 students; Budget: €374,3 Mio.)
 * University of Kassel (25,103 students; Budget: €291,5 Mio.)

There are many international schools in Hesse, primarily centred in and around Frankfurt.

Hesse is the only state in Germany where students have to study all three stanzas of the "Das Deutschlandlied".

Big Science
A single existing big science facility in Hesse is GSI Helmholtz Centre for Heavy Ion Research in Darmstadt-Wixhausen with 1,520 employees. The second one Facility for Antiproton and Ion Research is in construction till 2025.

In space research there are 2 European organization European Space Operations Center and European Organisation for the Exploitation of Meteorological Satellites in Darmstadt.

Health & Medicine

 * Max Planck Institute for Heart and Lung Research, Bad Nauheim
 * Max Planck Institute for Brain Research, Frankfurt-am-Main
 * Max Planck Institute of Biophysics, Frankfurt-am-Main
 * Max Planck Research Center for Neurogenetics, Frankfurt-am-Main
 * Fraunhofer Institute for Translational Medicine and Pharmacology, Frankfurt-am-Main
 * Paul Ehrlich Institute (vaccines), Langen
 * Max Planck Institute for Terrestrial Microbiology, Marburg
 * Institute of Virology (Marburg)(researh of Ebolavirus and Marburgvirus; Parasitology) with BSL4-Labor, Marburg
 * Center for undiagnosed and rare diseases, Marburg
 * Marburg Heavy Ion Beam Therapy Center, Marburg
 * Sigmund Freud Institute (psychoanalysis), Frankfurt-am-Main

Informatics & Software

 * German Research Centre for Artificial Intelligence, Darmstadt
 * Hessian Center for Artificial Intelligence (hessian.AI), HQ in Darmstadt, more locations in Hesse
 * Athene (research center), Darmstadt
 * Center for Advanced Security Research Darmstadt, Darmstadt
 * Fraunhofer Institute for Secure Information Technology, Darmstadt
 * Fraunhofer Institute for Graphic Data Processing, Darmstadt

Others

 * Fraunhofer Institute for Structural Durability and System Reliability, Darmstadt
 * Fraunhofer Institute for Energy Economics and Energy System Technology, HQ in Kassel, other location in Rothwesten and Bad Hersfeld
 * Fraunhofer Facility for Material Cycles and Resource Strategy, Hanau
 * Max-Planck-Institut für europäische Rechtsgeschichte, Frankfurt-am-Main
 * Institut für Sozialforschung at Johann Wolfgang Goethe-Universität Frankfurt-am-Main
 * Leibniz-Institut für Bildungsforschung und Bildungsinformation, Frankfurt-am-Main
 * Forschungsinstitut für Deutsche Sprache – Deutscher Sprachatlas – at Philipps-Universität Marburg
 * Paul-Ehrlich-Institut, * Forschungsinstitut und Naturmuseum Senckenberg, Frankfurt am Main
 * Peace Research Institute Frankfurt, Frankfurt-am-Main
 * Institut für sozial-ökologische Forschung, Frankfurt-am-Main

Culture
Hesse has a rich and varied cultural history, with many important cultural and historical centres and several UNESCO world-heritage sites.

Architecture, art, literature and music
Darmstadt has a rich cultural heritage as the former seat of the Landgraves and Grand Dukes of Hesse. It is known as centre of the art nouveau Jugendstil and modern architecture and there are also several important examples of 19th century architecture influenced by British and Russian imperial architecture due to close family ties of the Grand Duke's family to the reigning dynasties in London and Saint Petersburg in the Grand Duchy period. Darmstadt is an important centre for music, home of the Darmstädter Ferienkurse for contemporary classical music and the Jazz Institute Darmstadt, Europe's largest public jazz archive.

Frankfurt am Main is a major international cultural centre. Over 2 million people visit the city's approximately 60 exhibition centres every year. Amongst its most famous art galleries are the Schirn Kunsthalle, a major centre for international modern art, and the Städel, whose large collections include over 3000 paintings, 4000 photographs, and 100,000 drawings including works by Picasso, Monet, Rembrandt and Dürer. Goethe was born in Frankfurt and there is a museum in his birthplace. Frankfurt has many music venues, including an award-winning opera house, the Alte Oper, and the Jahrhunderthalle. Its several theatres include the English Theatre, the largest English-speaking theatre on the European continent.

Kassel has many palaces and parks, including Bergpark Wilhelmshöhe, a Baroque landscape park and UNESCO World Heritage site. The Brothers Grimm lived and worked in Kassel for 30 years and the recently opened Grimmwelt museum explores their lives, works and influence and features their personal copies of the Children's and Household Tales, which are on the UNESCO World Heritage "Memory of the World" Document register. The Fridericianum, built in 1779, is one of the oldest public museums in Europe. Kassel is also home to the documenta, a large modern art exhibition that has taken place every five years since the 1950s.

The Hessian Ministry of the Arts supports numerous independent cultural initiatives, organisations, and associations as well as artists from many fields including music, literature, theatre and dance, cinema and the new media, graphic art, and exhibitions. International cultural projects aim to further relations with European partners.

From an archaeological point of view, the old watercourses of Hesse provide evidence of the wider history of the landscape and their protection has required cooperation.

UNESCO World Heritage Sites
Hesse has several UNESCO World Heritage sites. These include:

 * Bergpark Wilhelmshöhe in Kassel
 * Kellerwald-Edersee National Park in North Hesse
 * Lorsch Abbey
 * The Messel Fossil Pit. Exhibits from the Messel Pit can be seen in Messel town museum, the Museum of Hessen in Darmstadt, and the Senckenberg Museum in Frankfurt.
 * The Saalburg, part of the Roman Limes.
 * Darmstadt Artists' Colony

Sports
Frankfurt hosts the following professional sports teams or clubs:

 * 1. FFC Frankfurt (1998–2020), football (women)
 * Eintracht Frankfurt, football (men, women)
 * FSV Frankfurt, football (men)
 * Rot-Weiss Frankfurt, football
 * Frankfurter FC Germania 1894, football
 * Skyliners Frankfurt, basketball
 * Frankfurt Galaxy (1991–2007), American football
 * Frankfurt Universe (2007–present), American football
 * Frankfurter Löwen (1979–1984), American football
 * Frankfurt Sarsfields GAA, Gaelic football
 * Frankfurt Lions (until 2010), ice hockey
 * Löwen Frankfurt (since 2010), ice hockey
 * SC 1880 Frankfurt, rugby union

Frankfurt is host to the classic cycle race Eschborn-Frankfurt City Loop (known as Rund um den Henninger-Turm from 1961 to 2008). The city hosts also the annual Frankfurt Marathon and the Ironman Germany.

Outside Frankfurt, notable professional sports teams include Kickers Offenbach, SV Darmstadt 98, Marburg Mercenaries, Gießen 46ers, MT Melsungen, VfB Friedberg, and the Kassel Huskies.

TV and radio stations
The Hessian state broadcasting corporation is called HR (Hessischer Rundfunk). HR is a member of the federal ARD broadcasting association. HR provides a statewide TV channel as well as a range of regional radio stations (HR 1, HR 2, HR 3, HR 4, you fm and HR info). Besides the state run HR, privately run TV stations exist and are an important line of commerce. Among the commercial radio stations that are active in Hesse, Hit Radio FFH, Planet Radio, Harmony FM, Radio BOB and Antenne Frankfurt are the most popular.

Financial
With Hesse's largest city Frankfurt am Main being home of the European Central Bank (ECB), the German Bundesbank and the Frankfurt Stock Exchange, Hesse is home to the financial capital of mainland Europe. Furthermore, Hesse has always been one of the largest and healthiest economies in Germany. Its GDP in 2013 exceeded €236 billion (about US$316 billion). This makes Hesse itself one of the largest economies in Europe and the 38th largest in the world. According to GDP-per-capita figures, Hesse is the wealthiest state (after the city-states Hamburg and Bremen) in Germany with approx. US$52,500.

Frankfurt is crucial as a financial center, with both the European Central Bank and the Deutsche Bundesbank's headquarters located there. Numerous smaller banks and Deutsche Bank, DZ Bank, KfW Bank, Commerzbank are also headquartered in Frankfurt, with the offices of several international banks also being housed there. Frankfurt is also the location of the most important German stock exchange, the Frankfurt Stock Exchange. Insurance companies have settled mostly in Wiesbaden. The city's largest private employer is the R+V Versicherung, with about 3,900 employees, other major employers are DBV-Winterthur, the SV SparkassenVersicherung and the Delta Lloyd Group.

Chemical & Pharma
The Rhine-Main Region has the second largest industrial density in Germany after the Ruhr area. The main economic fields of importance are the chemical and pharmaceutical industries with Sanofi, Merck, Heraeus, Stada, Messer Griesheim, Bayer Crop Science, SGL Carbon, Celanese, Cabot, Clariant, Akzo Nobel, Kuraray, Ineos, LyondellBasell, Allessa and Evonik Industries. But also other consumer goods are produced by Procter & Gamble, Coty and Colgate Palmolive. The Rhine-Main Region is not restricted only to Hesse, smaller part is in Rhineland-Palatinate. There situated 2 important pharma companies: BioNTech(HQ), which found the first mRNA vaccine against COVID-19 in the world (licensed to Pfizer), and Boehringer Ingelheim, close to Hesse's border in Mainz and Ingelheim respectively. It supports from Max Planck Institute for Heart and Lung Research, Max Planck Institute for Brain Research and Paul Ehrlich Institute.

Also in other part of Hesse there is important pharma and medical manufacturers, especially in Marburg where there is industry park based on ex-Behring Werke: BioNTech (mRNA vaccines), CSL Behring, Temmler and Melsungen with B. Braun. Pharma activity in Marburg is also supported from research facilities: Max Planck Institute for Terrestrial Microbiology, Center for undiagnosed and rare diseases, Institute of Virology (Marburg)(researh of Ebolavirus and Marburgvirus; Parasitology) with BSL4-Labor, Marburg Heavy Ion Beam Therapy Center.

Merck controls ca. 60% of world's liquid crystal market.

Heraeus, Umicore and Evonik Industries manufacture different type of catalysts from Platinum metals, Vanadium, Neodymium, Manganese, Copper etc.

In east Fulda there is the tire plant (Fulda Reifen). 2 other tire plants are in Korbach from Continental and Hanau from Goodyear.

Metallurgy & Nuclear
Specialised metallurgical industry focused on platinum metals has been represented by Heraeus and Umicore and magnetic materials have been a focus of Vacuumschmelze based in Hanau. Also in Hanau there used to be a plant producing nuclear fuel (classical uranium, but also MOX fuel), but the production has stopped and the facility has been mothballed. Heraeus continues to manufacture irradiation sources from Cobalt and Iridium.

Engineering
In the mechanical and automotive engineering field Opel in Rüsselsheim is worth mentioning. After acquisition Opel by Stellantis, it is in rapid decline of production and employment. Which has also negative effect on automotive parts supplier, Continental will close a plant in Karben and cut jobs at other location in Hesse. In northern Hesse, in Baunatal, Volkswagen AG has a large factory that manufactures spare parts, not far-away from it there is also a Daimler Truck plant, which produces an axes.

Alstom, after takeover of Bombardier, has a large plant that manufactures Traxx locomotives in Kassel. Industrial printers (Manroland, Gallus Holding), x-ray airport check equipment (Smiths), handling and loading equipment (Dematic), chemical equipment (Air Liquide Global E&C Solutions), vacuum pumps (Pfeiffer Vacuum), vacuum industrial furnace (ALD Vacuum Technologies), textile machines (Karl Mayer), shavers (Braun), medical (Fresenius, Sirona) and industrial (Schenck Process, Samson) apparatuses are produced in Rhine-Main Region.

Manufacturing of heating boilers and heat pumps are typical for Hesse and represented with Bosch Thermotechnik and Viessmann.

Vistec produces electron-beam lithography systems for semiconductor industry in Weilburg, also there is manufacturing of inspection, testing and measurement equipment for semiconductor fabrication process from KLA-Tencor. Leica Microsystems manufactures different types of microscopes, inclusive they with special light microscopic optics, which are used in wafer and photo mask testing. PVA TePla from Wettenberg is specialist for crystal growing process (Si, Ge, GaAs, GaP, InP) with Czochralski Process, Float-Zone Process, High-Temperature Chemical Vapor Deposition, Vertical Gradient Freeze equipment, quality inspection apparatus, plasma and vacuum machine. ABB Robotics is in Friedberg. Satisloh is a machine manufacturer in Wetzlar for the production of lenses and components for the optical industry.

Aerospace
The company operating Frankfurt Airport is one of the largest employers in Hesse with nearly 22,000 employees. Aerospace cluster contains also Rolls-Royce's aviation engine work in Oberursel and APU manufacturing plant and service center of Honeywell in Raunheim.

Optics & Electronics
Companies with an international reputation are located outside the Rhine-Main region in Wetzlar. There is the center of the optical, electrical and precision engineering industries, Leitz, Leica, Minox, Hensoldt (Zeiss) and Brita with several plants in central Hesse.

Oculus Optikgeräte manufactures Scheimpflug tomographs for examining the anterior segment of the eye, topographers for measuring the anterior surface of the cornea, tonometers for assessing the biomechanical properties of the cornea, a wide-angle observation system for vitreous body surgery, universal trial goggles for subjective refraction, various perimeters for visual field testing and vision testing devices for testing eyesight.

Electrical transformers are produced by Hitachi ABB Power Grids in Hanau and Siemens Energy in Frankfurt-am-Main. SMA Solar Technology manufactures an inverters for photovoltaic systems. Rittal is specialized on electrical enclosure situated in Herborn and Eschenburg. Power semiconductors from IXYS in Lampertheim and UV and infrared lamps from Heraeus.

IT & Telecom
Many IT and telecommunications companies are located in Hesse, many of them in Frankfurt and Darmstadt, like Software AG (Darmstadt), T-Systems (Frankfurt and Darmstadt), Deutsche Telekom (laboratories in Darmstadt), DB Systel (Frankfurt), Lufthansa Systems (Raunheim near Frankfurt) and DE-CIX (Frankfurt).

Food & Beverage
Sweet making is typical, there are 2 big factories: Ferrero, Stadtallendorf and Baronie (Sarotti), Hattersheim am Main. Frankfurter Sausage is famous, but there is also other sorts like Frankfurter Rindswurst, Ahle Wurst.

Beverage industry is well-developed and manufactures sparkling wine (Sekt), white wine (Riesling), mineral waters (Selters), beers (Radeberger) and cider.

In Frankfurt-Oberrad exists growing of wild herbs for green sauce and monument.

Defunct Industries
The leather industry was predominantly based in Offenbach, but is now extinct, existing only in museums. The same happened with Frankfurt's fur industry and Hanau's jewelry industry.

Unemployment
The Hochtaunuskreis has the lowest unemployment rate at 3.8% while the independent city of Kassel has the highest rate nationally at 12.1%. In October 2018 the unemployment rate stood at 4.4% and was lower than the national average.

Road transport
Hesse has a dense highway network with a total of 24 motorways. The internationally important motorway routes through Hesse are the A3, A5, and A7. Close to Frankfurt Airport is the Frankfurter Kreuz, Germany's busiest and one of Europe's busiest motorway junctions, where the motorways A3 (Arnhem-Cologne-Frankfurt-Nuremberg-Passau) and A5 (Hattenbach-Frankfurt-Karlsruhe-Basel) intersect. The A5 becomes as wide as four lanes in each direction near the city of Frankfurt am Main, and during the rush-hour, it is possible to use the emergency lanes on the A3 and A5 motorway in the Rhine-Main Region, adding additional lanes. Other major leading Hesse highways are the A4, the A44, the A45, the Federal Highway A66 and the A67. There are also a number of smaller motorways and major trunk roads, some of which are dual carriageways.

Railway transport
Hesse is accessed by many major rail lines, including the high-speed lines Cologne–Frankfurt(op.speed 300 km/h) and Hanover–Würzburg. Other north-south connections traverse major east–west routes from Wiesbaden and Mainz to Frankfurt and from Hanau and Aschaffenburg to Fulda and Kassel. The Frankfurt Central Station is the most important hub for German trains, with over 1,100 trains per day.

The region around Frankfurt has an extensive S-Bahn network, the S-Bahn Rhein-Main, which is complemented by many regional train connections. In the rest of the country, the rail network is less extensive. Since 2007, the region around Kassel has been served by the RegioTram, a tram-train-concept similar to the Karlsruhe model.

Air transport
Frankfurt Airport is by far the largest airport in Germany with more than 57 million passengers each year, is and among the world's ten largest. Frankfurt Egelsbach Airport lies to the south, and is frequented by general aviation and private planes. Kassel Airport offers a few flights to holiday destinations, but has struggled to compete. There are also a number of sports airfields. Low-cost airlines, especially Ryanair, use Frankfurt-Hahn Airport as a major base, although the airport is actually located about 100 km from Frankfurt in the neighbouring state of Rhineland-Palatinate. The DFS (German air traffic control) has its headquarters in Langen.

title: Hesse


text:
Activation energy

In the Arrhenius model of reaction rates, activation energy is the minimum amount of energy that must be available to reactants for a chemical reaction to occur. The activation energy (Ea) of a reaction is measured in kilojoules per mole (kJ/mol) or kilocalories per mole (kcal/mol). Activation energy can be thought of as the magnitude of the potential barrier (sometimes called the energy barrier) separating minima of the potential energy surface pertaining to the initial and final thermodynamic state. For a chemical reaction to proceed at a reasonable rate, the temperature of the system should be high enough such that there exists an appreciable number of molecules with translational energy equal to or greater than the activation energy. The term "activation energy" was introduced in 1889 by the Swedish scientist Svante Arrhenius.

Other uses
Although less commonly used, activation energy also applies to nuclear reactions and various other physical phenomena.

Temperature dependence and the relation to the Arrhenius equation
The Arrhenius equation gives the quantitative basis of the relationship between the activation energy and the rate at which a reaction proceeds. From the equation, the activation energy can be found through the relation $$k = A e^{{-E_\textrm{a}}/{(RT)}}$$

where A is the pre-exponential factor for the reaction, R is the universal gas constant, T is the absolute temperature (usually in kelvins), and k is the reaction rate coefficient. Even without knowing A, Ea can be evaluated from the variation in reaction rate coefficients as a function of temperature (within the validity of the Arrhenius equation).

At a more advanced level, the net Arrhenius activation energy term from the Arrhenius equation is best regarded as an experimentally determined parameter that indicates the sensitivity of the reaction rate to temperature. There are two objections to associating this activation energy with the threshold barrier for an elementary reaction. First, it is often unclear as to whether or not reaction does proceed in one step; threshold barriers that are averaged out over all elementary steps have little theoretical value. Second, even if the reaction being studied is elementary, a spectrum of individual collisions contributes to rate constants obtained from bulk ('bulb') experiments involving billions of molecules, with many different reactant collision geometries and angles, different translational and (possibly) vibrational energies—all of which may lead to different microscopic reaction rates.

Catalysts
A substance that modifies the transition state to lower the activation energy is termed a catalyst; a catalyst composed only of protein and (if applicable) small molecule cofactors is termed an enzyme. A catalyst increases the rate of reaction without being consumed in the reaction. In addition, the catalyst lowers the activation energy, but it does not change the energies of the original reactants or products, and so does not change equilibrium. Rather, the reactant energy and the product energy remain the same and only the activation energy is altered (lowered).

A catalyst is able to reduce the activation energy by forming a transition state in a more favorable manner. Catalysts, by nature, create a more "comfortable" fit for the substrate of a reaction to progress to a transition state. This is possible due to a release of energy that occurs when the substrate binds to the active site of a catalyst. This energy is known as Binding Energy. Upon binding to a catalyst, substrates partake in numerous stabilizing forces while within the active site (e.g. hydrogen bonding or van der Waals forces). Specific and favorable bonding occurs within the active site until the substrate forms to become the high-energy transition state. Forming the transition state is more favorable with the catalyst because the favorable stabilizing interactions within the active site release energy. A chemical reaction is able to manufacture a high-energy transition state molecule more readily when there is a stabilizing fit within the active site of a catalyst. The binding energy of a reaction is this energy released when favorable interactions between substrate and catalyst occur. The binding energy released assists in achieving the unstable transition state. Reactions without catalysts need a higher input of energy to achieve the transition state. Non-catalyzed reactions do not have free energy available from active site stabilizing interactions, such as catalytic enzyme reactions.

Relationship with Gibbs energy of activation
In the Arrhenius equation, the term activation energy (Ea) is used to describe the energy required to reach the transition state, and the exponential relationship $k = A exp(−E_{a}/RT)$ holds. In transition state theory, a more sophisticated model of the relationship between reaction rates and the transition state, a superficially similar mathematical relationship, the Eyring equation, is used to describe the rate constant of a reaction: $k = (k_{B}T / h) exp(−ΔG^{‡} / RT)$. However, instead of modeling the temperature dependence of reaction rate phenomenologically, the Eyring equation models individual elementary steps of a reaction. Thus, for a multistep process, there is no straightforward relationship between the two models. Nevertheless, the functional forms of the Arrhenius and Eyring equations are similar, and for a one-step process, simple and chemically meaningful correspondences can be drawn between Arrhenius and Eyring parameters.

Instead of also using Ea, the Eyring equation uses the concept of Gibbs energy and the symbol ΔG‡ to denote the Gibbs energy of activation to achieve the transition state. In the equation, kB and h are the Boltzmann and Planck constants, respectively. Although the equations look similar, it is important to note that the Gibbs energy contains an entropic term in addition to the enthalpic one. In the Arrhenius equation, this entropic term is accounted for by the pre-exponential factor A. More specifically, we can write the Gibbs free energy of activation in terms of enthalpy and entropy of activation: $ΔG^{‡} = ΔH^{‡} − T ΔS^{‡}$. Then, for a unimolecular, one-step reaction, the approximate relationships $E_{a} = ΔH^{‡} + RT$ and $A = (k_{B}T/h) exp(1 + ΔS^{‡}/R)$ hold. Note, however, that in Arrhenius theory proper, A is temperature independent, while here, there is a linear dependence on T. For a one-step unimolecular process whose half-life at room temperature is about 2 hours, ΔG‡ is approximately 23 kcal/mol. This is also the roughly the magnitude of Ea for a reaction that proceeds over several hours at room temperature. Due to the relatively small magnitude of TΔS‡ and RT at ordinary temperatures for most reactions, in sloppy discourse, Ea, ΔG‡, and ΔH‡ are often conflated and all referred to as the "activation energy".

The enthalpy, entropy and Gibbs energy of activation are more correctly written as Δ‡Ho, Δ‡So and Δ‡Go respectively, where the o indicates a quantity evaluated between standard states. However, some authors omit the o in order to simplify the notation.

The total free energy change of a reaction is independent of the activation energy however. Physical and chemical reactions can be either exergonic or endergonic, but the activation energy is not related to the spontaneity of a reaction. The overall reaction energy change is not altered by the activation energy.

Negative activation energy
In some cases, rates of reaction decrease with increasing temperature. When following an approximately exponential relationship so the rate constant can still be fit to an Arrhenius expression, this results in a negative value of Ea.

Elementary reactions exhibiting negative activation energies are typically barrierless reactions, in which the reaction proceeding relies on the capture of the molecules in a potential well. Increasing the temperature leads to a reduced probability of the colliding molecules capturing one another (with more glancing collisions not leading to reaction as the higher momentum carries the colliding particles out of the potential well), expressed as a reaction cross section that decreases with increasing temperature. Such a situation no longer leads itself to direct interpretations as the height of a potential barrier.

Some multistep reactions can also have apparent negative activation energies. For example, the overall rate constant k for a two-step reaction A B, B → C is given by k = k2K1, where k2 is the rate constant of the rate-limiting slow second step and K1 is the equilibrium constant of the rapid first step. In some reactions, K1 decreases with temperature more rapidly than k2 increases, so that k actually decreases with temperature corresponding to a negative observed activation energy.

An example is the oxidation of nitric oxide which is a termolecular reaction. The rate law is $$v = k \, \left[ {\rm NO} \right]^2 \, \left[ {\rm O_2} \right]$$ with a negative activation energy. This is explained by the two-step mechanism: and.

Certain cationic polymerization reactions have negative activation energies so that the rate decreases with temperature. For chain-growth polymerization, the overall activation energy is $$\textstyle E = E_i + E_p - E_t$$, where i, p and t refer respectively to initiation, propagation and termination steps. The propagation step normally has a very small activation energy, so that the overall value is negative if the activation energy for termination is larger than that for initiation. The normal range of overall activation energies for cationic polymerization varies from $40 kJ$.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Activation energy


text:
North Rhine-Westphalia

North Rhine-Westphalia or North-Rhine/Westphalia (Nordrhein-Westfalen, ; Noordrien-Wesfale ; Noordryn-Westfaulen or Noordrhien-Westfalen), commonly shortened to NRW, is a state (Land) in Western Germany. With more than 18 million inhabitants, it is the most populous state in Germany. Apart from the city-states, it is also the most densely populated state in Germany. Covering an area of 34084 km2, it is the fourth-largest German state by size.

North Rhine-Westphalia features 30 of the 81 German municipalities with over 100,000 inhabitants, including Cologne (over 1 million), the state capital Düsseldorf (630.000), Dortmund and Essen (about 590,000 inhabitants each) and other cities predominantly located in the Rhine-Ruhr metropolitan area, the largest urban area in Germany and the fourth-largest on the European continent. The location of the Rhine-Ruhr at the heart of the European Blue Banana makes it well connected to other major European cities and metropolitan areas like the Randstad, the Flemish Diamond and the Frankfurt Rhine-Main Region.

North Rhine-Westphalia was established in 1946 after World War II from the Prussian provinces of Westphalia and the northern part of Rhine Province (North Rhine), and the Free State of Lippe by the British military administration in Allied-occupied Germany and became a state of the Federal Republic of Germany in 1949. The city of Bonn served as the federal capital until the reunification of Germany in 1990 and as the seat of government until 1999.

Culturally, North Rhine-Westphalia is not a uniform area; there are significant differences, especially in traditional customs, between the Rhineland region on the one hand and the regions of Westphalia and Lippe on the other. As of 2023, its economy is the largest among German states by GDP but is below the national average in GDP per capita.

Creation
The state of North Rhine-Westphalia was established by the British military administration's "Operation Marriage" on 23 August 1946 by merging the province of Westphalia and the northern parts of the Rhine Province, both being political divisions of the former state of Prussia within the German Reich. On 21 January 1947, the former state of Lippe was merged with North Rhine-Westphalia. The constitution of North Rhine-Westphalia was then ratified through a referendum.

Rhineland
The first written account of the area was by its conqueror, Julius Caesar, the territories west of the Rhine were occupied by the Eburones and east of the Rhine he reported the Ubii (across from Cologne) and the Sugambri to their north. The Ubii and some other Germanic tribes such as the Cugerni were later settled on the west side of the Rhine in the Roman province of Germania Inferior. Julius Caesar conquered the tribes on the left bank, and Augustus established numerous fortified posts on the Rhine, but the Romans never succeeded in gaining a firm footing on the right bank, where the Sugambri neighboured several other tribes including the Tencteri and Usipetes. North of the Sigambri and the Rhine region were the Bructeri.

As the power of the Roman empire declined, many of these tribes came to be seen collectively as Ripuarian Franks and they pushed forward along both banks of the Rhine, and by the end of the fifth century had conquered all the lands that had formerly been under Roman influence. By the eighth century, the Frankish dominion was firmly established in western Germany and northern Gaul, but at the same time, to the north, Westphalia was being taken over by Saxons pushing south.

The Merovingian and Carolingian Franks eventually built an empire which controlled first their Ripuarian kin, and then the Saxons. On the division of the Carolingian Empire at the Treaty of Verdun, the part of the province to the east of the river fell to East Francia, while that to the west remained with the kingdom of Lotharingia.

By the time of Otto I (d. 973), both banks of the Rhine had become part of the Holy Roman Empire, and the Rhenish territory was divided between the duchies of Upper Lorraine on the Moselle and Lower Lorraine on the Meuse. The Ottonian dynasty had both Saxon and Frankish ancestry.

As the central power of the Holy Roman Emperor weakened, the Rhineland split into numerous small, independent, separate vicissitudes and special chronicles. The old Lotharingian divisions became obsolete, although the name survives for example in Lorraine in France, and throughout the Middle Ages and even into modern times, the nobility of these areas often sought to preserve the idea of a preeminent duke within Lotharingia, something claimed by the Dukes of Limburg, and the Dukes of Brabant. Such struggles as the War of the Limburg Succession therefore continued to create military and political links between what is now Rhineland-Westphalia and neighbouring Belgium and the Netherlands.

In spite of its dismembered condition and the sufferings it underwent at the hands of its French neighbours in various periods of warfare, the Rhenish territory prospered greatly and stood in the foremost rank of German culture and progress. Aachen was the place of coronation of the German emperors, and the ecclesiastical principalities of the Rhine bulked largely in German history.

Prussia first set foot on the Rhine in 1609 by the occupation of the Duchy of Cleves and about a century later Upper Guelders and Moers also became Prussian. At the peace of Basel in 1795, the whole of the left bank of the Rhine was resigned to France, and in 1806, the Rhenish princes all joined the Confederation of the Rhine.

After the Congress of Vienna, Prussia was awarded the entire Rhineland, which included the Grand Duchy of Berg, the ecclesiastic electorates of Trier and Cologne, the free cities of Aachen and Cologne, and nearly a hundred small lordships and abbeys. The Prussian Rhine province was formed in 1822 and Prussia had the tact to leave the lower Rhenish districts in undisturbed possession of the liberal institutions to which they had become accustomed under the republican rule of the French. In 1920, the districts of Eupen and Malmedy were transferred to Belgium (see German-speaking Community of Belgium).

Westphalia
Around AD 1, numerous incursions occurred through Westphalia and perhaps even some permanent Roman or Romanized settlements. The Battle of Teutoburg Forest took place near Osnabrück and some of the Germanic tribes who fought at this battle came from the area of Westphalia. Charlemagne is thought to have spent considerable time in Paderborn and nearby parts. His Saxon Wars also partly took place in what is thought of as Westphalia today. Popular legends link his adversary Widukind to places near Detmold, Bielefeld, Lemgo, Osnabrück, and other places in Westphalia. Widukind was buried in Enger, which is also a subject of a legend.

Along with Eastphalia and Engern, Westphalia (Westfalahi) was originally a district of the Duchy of Saxony. In 1180, Westphalia was elevated to the rank of a duchy by Emperor Barbarossa. The Duchy of Westphalia comprised only a small area south of the Lippe River.

Parts of Westphalia came under Brandenburg-Prussian control during the 17th and 18th centuries, but most of it remained divided duchies and other feudal areas of power. The Peace of Westphalia of 1648, signed in Münster and Osnabrück, ended the Thirty Years' War. The concept of nation-state sovereignty resulting from the treaty became known as "Westphalian sovereignty".

As a result of the Protestant Reformation, there is no dominant religion in Westphalia. Catholicism and Lutheranism are on relatively equal footing. Lutheranism is strong in the eastern and northern parts with numerous free churches. Münster and especially Paderborn are thought of as Catholic. Osnabrück is divided almost equally between Catholicism and Protestantism.

After the defeat of the Prussian Army at the Battle of Jena-Auerstedt, the Treaty of Tilsit in 1807 made the Westphalian territories part of the Kingdom of Westphalia from 1807 to 1813. It was founded by Napoleon and was a French vassal state. This state only shared the name with the historical region; it contained only a relatively small part of Westphalia, consisting instead mostly of Hessian and Eastphalian regions.

After the Congress of Vienna, the Kingdom of Prussia received a large amount of territory in the Westphalian region and created the province of Westphalia in 1815. The northernmost portions of the former kingdom, including the town of Osnabrück, had become part of the states of Hanover and Oldenburg.

Flags and coat of arms
The flag of North Rhine-Westphalia is green-white-red with the combined coats of arms of the Rhineland (white line before green background, symbolizing the river Rhine), Westfalen (the white horse) and Lippe (the red rose). After the establishment of North Rhine-Westphalia in 1946, the tricolor was first introduced in 1948, but was not formally adopted until 1953. The plain variant of the tricolor is considered the civil flag and state ensign, while government authorities use the state flag (Landesdienstflagge) which is defaced with the state's coat of arms. The state ensign can easily be mistaken for a distressed flag of Hungary, as well as the former national flag of Iran (1964–1980). The same flag was used by the Rhenish Republic (1923–1924) as a symbol of independence and freedom.

The horse on the coat of arms is a reference to the Saxon Steed, a heraldic motif associated with both Westphalia and Lower Saxony. The horse first featured in the 15th century coat of arms of the Duchy of Westphalia, before being inherited by the Prussian province of Westphalia and finally the modern state of North Rhine-Westphalia.

Geography

North Rhine-Westphalia encompasses the plains of the Lower Rhine region and parts of the Central Uplands (die Mittelgebirge) up to the gorge of Porta Westfalica. The state covers an area of 34,083 km2 and shares borders with Belgium (Wallonia) in the southwest and the Netherlands (Limburg, Gelderland and Overijssel) in the west and northwest. It has borders with the German states of Lower Saxony to the north and northeast, Rhineland-Palatinate to the south and Hesse to the southeast.

Approximately half of the state is located in the relative low-lying terrain of the Westphalian Lowland and the Rhineland, both extending broadly into the North German Plain. A few isolated hill ranges are located within these lowlands, among them the Hohe Mark, the Beckum Hills, the Baumberge and the Stemmer Berge. The terrain rises towards the south and in the east of the state into parts of Germany's Central Uplands. These hill ranges are the Weser Uplands – including the Egge Hills, the Wiehen Hills, the Wesergebirge and the Teutoburg Forest in the east, the Sauerland, the Bergisches Land, the Siegerland and the Siebengebirge in the south, as well as the left-Rhenish Eifel in the southwest of the state. The Rothaargebirge in the border region with Hesse rises to height of about 800 m above sea level. The highest of these mountains are the Langenberg, at 843.2 m above sea level, the Kahler Asten (840.7 m) and the Clemensberg (839.2 m).

The planimetrically determined centre of North Rhine-Westphalia is located in the south of Dortmund-Aplerbeck in the Aplerbecker Mark (51° 28' N, 7° 33' Ö). Its westernmost point is situated near Selfkant close to the Dutch border, the easternmost near Höxter on the Weser. The southernmost point lies near Hellenthal in the Eifel region. The northernmost point is the NRW-Nordpunkt near Rahden in the northeast of the state. The Nordpunkt has located the only 100 km to the south of the North Sea coast. The deepest natural dip is arranged in the district Zyfflich in the city of Kranenburg with 9.2 m above sea level in the northwest of the state. Though, the deepest point overground results from mining. The open-pit Hambach reaches at Niederzier a deep of 293 m below sea level. At the same time, this is the deepest human-made dip in Germany.

The most important rivers flowing at least partially through North Rhine-Westphalia include: the Rhine, the Ruhr, the Ems, the Lippe, and the Weser. The Rhine is by far the most important river in North Rhine-Westphalia: it enters the state as Middle Rhine near Bad Honnef, where still being part of the Mittelrhein wine region. It changes into the Lower Rhine near Bad Godesberg and leaves North Rhine-Westphalia near Emmerich at a width of 730 metres. Almost immediately after entering the Netherlands, the Rhine splits into many branches.

The Pader, which flows entirely within the city of Paderborn, is considered Germany's shortest river.

For many, North Rhine-Westphalia is synonymous with industrial areas and urban agglomerations. However, the largest part of the state is used for agriculture (almost 52%) and forests (25%).

Subdivisions

The state consists of five government regions (Regierungsbezirke), divided into 31 districts (Kreise) and 23 urban districts (kreisfreie Städte). In total, North Rhine-Westphalia has 396 municipalities (1997), including the urban districts, which are municipalities by themselves. The government regions have an assembly elected by the districts and municipalities, while the Landschaftsverband has a directly elected assembly.

The five government regions of North Rhine-Westphalia each belong to one of the two Landschaftsverbände:

Borders
The state's area covers a maximum distance of 291 km from north to south, and 266 km from east to west. The total length of the state's borders is 1,645 km. The following countries and states have a border with North Rhine-Westphalia:
 * Belgium (99 km)
 * Netherlands (387 km)
 * Lower Saxony (583 km)
 * Hesse (269 km)
 * Rhineland-Palatinate (307 km)

Demographics

North Rhine-Westphalia has a population of approximately 18.1 million inhabitants (more than the entire former East Germany, and slightly more than the Netherlands) and is centred around the polycentric Rhine-Ruhr metropolitan region, which includes the industrial Ruhr region with the largest city of Dortmund and the Rhenish cities of Bonn, Cologne and Düsseldorf. 30 of the 80 largest cities in Germany are located within North Rhine-Westphalia. The state's capital is Düsseldorf; the state's largest city is Cologne. In 2022, there were 164,496 births and 234,176 deaths.

The following table shows the ten largest cities of North Rhine-Westphalia:

Historical population
The following table shows the population of the state since 1930. The values until 1960 are the average of the yearly population, from 1965 the population at year end is used.

Vital statistics
Source: Statistische Ämter des Bundes Und der Länder
 * Births from January–September 2016 = 130,025
 * Births from January–September 2017 = 130,088
 * Deaths from January–September 2016 = 150,018
 * Deaths from January–September 2017 = 153,435
 * Natural growth from January–September 2016 = −19,993
 * Natural growth from January–September 2017 = −23,347

Religion
, 50% of the population of the state adhered to the Roman Catholic Church, 25% to the Protestant Church in Germany, and 28% of the population is irreligious or adheres to other denominations or religions. North Rhine-Westphalia ranks first in population among German states for both Roman Catholics and Protestants.

In 2016, the interior ministry of North Rhine-Westphalia reported that the number of mosques with a Salafist influence had risen from 3 to 9, which indicated both an actual increase and improved reporting. According to German authorities, Salafism is incompatible with the principles codified in the Constitution of the Federal Republic of Germany, in particular: democracy, the rule of law, and political order based on human rights.

Politics

The politics of North Rhine-Westphalia takes place within a framework of a federal parliamentary representative democratic republic. The two main parties are, as on the federal level, the centre-right Christian Democratic Union and the centre-left Social Democratic Party. From 1966 to 2005, North Rhine-Westphalia was continuously governed by the Social Democrats or SPD-led governments.

The state's legislative body is the Landtag ("state parliament house"). It may pass laws within the competency of the state, e.g. cultural matters, the education system, matters of internal security, i.e. the police, building supervision, health supervision and the media; as opposed to matters that are reserved to Federal law.

North Rhine-Westphalia uses the same electoral system as the Federal level in Germany: "Personalized proportional representation". Every five years the citizens of North Rhine-Westphalia vote in a general election to elect at least 181 members of the Landtag. Only parties who win at least 5% of the votes cast may be represented in parliament.

The Landtag, the parliamentary parties and groups consisting of at least 7 members of parliament have the right to table legal proposals to the Landtag for deliberation. The law that is passed by the Landtag is delivered to the Minister-President, who, together with the ministers involved, is required to sign it and announce it in the Law and Ordinance Gazette.

List of ministers-president
These are the ministers-president of North Rhine-Westphalia:

For the current state government, see Wüst cabinet.

Architecture and building monuments

 * The state is known for the most castles and fortresses in Germany.
 * North Rhine-Westphalia has a high concentration of museums, cultural centres, concert halls and theatres.

World Heritage Sites
The state has Aachen Cathedral, the Cologne Cathedral, the Zeche Zollverein in Essen, the Augustusburg Palace in Brühl and the Imperial Abbey of Corvey in Höxter which are all World Heritage Sites.

Drinks

 * Kölsch is a local beer speciality brewed in Cologne.
 * Alt is a local beer speciality brewed in Düsseldorf and the Lower Rhine Region.
 * Dortmunder Export is a local pale lager beer speciality brewed in Dortmund.

Festivals
North Rhine-Westphalia hosts film festivals in Cologne, Bonn, Dortmund, Duisburg, Münster, Oberhausen and Lünen.

Other large festivals include Rhenish carnivals, Ruhrtriennale.

Every year Gamescom is hosted in Cologne. It is the largest video game convention in Europe.

Music

 * The composer Ludwig van Beethoven was born in Bonn in 1770.
 * A regional anthem is the Lied für NRW (Song for NRW).
 * North Rhine-Westphalia is home to many of Germany's best-known heavy metal, speed metal and thrash metal bands: Accept, Angel Dust, Blind Guardian, Doro (formerly of Warlock), Grave Digger, Holy Moses, Kreator, Rage, Scanner and Sodom. Also, North Rhine-Westphalia is home to Kraftwerk, originally a Krautrock band for four years, then later a synth-pop band.

Economy
North Rhine-Westphalia has always been Germany's powerhouse with the largest economy among the German states by GDP figures.

In the 1950s and 1960s, Westphalia was known as Land von Kohle und Stahl (Land of Coal and Steel). In the post-World War II recovery, the Ruhr was one of the most important industrial regions in Europe, and contributed to the German Wirtschaftswunder. As of the late 1960s, repeated crises led to contractions of these industrial branches. On the other hand, producing sectors, particularly in mechanical engineering and metal and iron working industry, experienced substantial growth. Despite this structural change and an economic growth which was under national average, the 2018 GDP of 705 billion euro (1/4 of the total German GDP) made NRW the economically strongest state of Germany by GRP figures, as well as one of the most important economical areas in the world. Of Germany's top 100 corporations, 37 are based in North Rhine-Westphalia. On a per capita base, however, North Rhine-Westphalia remains one of the weaker among the Western German states.

North Rhine-Westphalia attracts companies from both Germany and abroad. In 2009, the state had the most foreign direct investments (FDI) anywhere in Germany. Around 13,100 foreign companies from the most important investment countries control their German or European operations from bases in North Rhine-Westphalia.

There have been many changes in the state's economy in recent times. Among the many changes in the economy, employment in the creative industries is up while the mining sector is employing fewer people. Industrial heritage sites are now workplaces for designers, artists and the advertising industry. The Ruhr region has – since the 1960s – undergone a significant structural change away from coal mining and steel industry. Many rural parts of Eastern Westphalia, Bergisches Land and the Lower Rhine ground their economy on "Hidden Champions" in various sectors.

As of June 2014, the unemployment rate is 8.2%, second highest among all western German states. In October 2018 the unemployment rate stood at 6.4% and was higher than the national average.

Transport
With its central location in the most important European economic area, high population density, strong urbanization and numerous business locations, North Rhine-Westphalia has one of the densest transport networks in the world.

Regional rail network
The regional rail network is organised around the big cities on the Rhine and Ruhr such as Cologne, Düsseldorf and Dortmund. The public transport companies in the Ruhr area and Düsseldorf are run under the umbrella of the Verkehrsverbund Rhein-Ruhr, which provides a uniform ticket system valid for the area. The region of Cologne and Bonn is run under the Verkehrsverbund Rhein-Sieg. There is also a ticketing system called NRW-Tarif which offers tickets between all the regions of North Rhine-Westphalia. The state is well-integrated into the national rail system, the Deutsche Bahn, for both passenger and goods services, each city in the region has at least one or more train stations. The bigger central stations have frequent direct connections to most bigger German cities and European cities such as Amsterdam, Brussels, Paris and Basel. Some direct trains run to Vienna and Zürich.

The Rhein-Ruhr area also contains some of the longest tram system in the world, with tram and Stadtbahn services from Witten to Krefeld in the VRR zone and Cologne to Bad Honnef and Siegburg via Bonn within the VRS zone. Besides the local public transportation there is an interconnected commuter rail network, with the Rhine-Ruhr S-Bahn network serving the Ruhr area as well as Düsseldorf and the S-Bahn Köln serving the area around Cologne.

, the VRR network alone consists of 978 lines, of which there are:
 * in regional rail transit
 * 11 S-Bahn lines (see: Rhine-Ruhr S-Bahn)
 * 15 RegionalExpress lines (see: List of regional railway lines in North Rhine-Westphalia)
 * 24 RegionalBahn lines (see: List of regional railway lines in North Rhine-Westphalia)
 * in local rail transit
 * 19 Stadtbahn light rail lines (see: Rhine-Ruhr Stadtbahn)
 * 45 tram (Straßenbahn) lines
 * 1 Schwebebahn line (in Wuppertal)
 * 2 H-Bahn peoplemover systems made up of three lines (two H-Bahn lines in Dortmund, and the Düsseldorf SkyTrain at Düsseldorf airport)
 * in bus transit
 * 906 bus lines, including
 * 33 express bus lines (Schnellbus, SB)
 * 18 semi-fast bus lines (CityExpress, CE)
 * 6 trolleybus lines (in Solingen)
 * 15,300 km of route network (bus, light rail, and train)
 * 11,500 transit stops

In 2022 the VRS and AVV area contains
 * in regional rail transit
 * 7 S-Bahn lines (with 4 being part of the Rhein-Ruhr S-Bahn)
 * 11 RegionalExpress lines (6 conntected to VRR)
 * 18 RegionalBahn services
 * in local rail transit
 * 16 Stadtbahn lines (see: Cologne Stadtbahn and Bonn Stadtbahn)
 * 3 streetcar (Straßenbahn) lines within the city of Bonn

Road
North Rhine-Westphalia has the densest network of Autobahns in Germany and similar Schnellstraßen (expressways). The Autobahn network is built in a grid network, with five east–west (A2, A4, A40, A42, A44) and eight north–south (A1, A3, A43, A45, A52, A57, A59, A61) routes. The A1, A2, A3, A4 and A61 are mostly used by through traffic, while the other autobahns have a more regional function.

Both the A44 and the A52 have several missing links, in various stages of planning. Some missing sections are currently in construction or planned to be constructed in the near future.

Additional expressways serve as bypasses and local routes, especially around Dortmund and Bochum. Due to the density of the autobahns and expressways, Bundesstraßen are less important for intercity traffic. The first Autobahns in the Region opened during the mid-1930s. Due to the density of the network, and the number of alternative routes, traffic volumes are generally lower than other major metropolitan areas in Europe. Traffic congestion is an everyday occurrence, but far less so than in the Randstad in the Netherlands, another polycentric urban area. Most important Autobahns have six lanes.

Airports
The region benefits from the presence of several airport infrastructure. The main airport is Düsseldorf Airport, world class, which hosted 25.5 million passengers in 2019 and offers flights to various international destinations. Düsseldorf is the fourth-largest airport in Germany after Frankfurt, Munich and Berlin and serves as an hub for Eurowings and as focus city for several more airlines. The airport has three passenger terminals and two runways and can handle wide-body aircraft up to the Airbus A380.

The second airport is the international airport of Germany's fourth-largest city Cologne, and also serves Bonn, former capital of West Germany. With around 10 million passengers passing through it in 2023, it is the sixth-largest passenger airport in Germany and the third-largest in terms of cargo operations. It is also a hub for Eurowings, but also for some cargo airlines. By traffic units, which combines cargo and passengers, the airport is in fifth position in Germany. As of March 2015, Cologne Bonn Airport had services to 115 passenger destinations in 35 countries. It is named after Konrad Adenauer, a Cologne native and the first post-war Chancellor of West Germany.

Third airport in the region, Dortmund Airport is a minor international airport located 10 km east of Dortmund. It serves the eastern Rhine-Ruhr area, the largest urban agglomeration in Germany, and is mainly used for low-cost and leisure charter flights. In 2019 the airport served 2,719,563 passengers.

There are three more minor airports within the state: Münster Osnabrück Airport, Airport Weeze and Paderborn Lippstadt Airport.

Waterways
The Rhine flows through North Rhine-Westphalia. Its banks are usually heavily populated and industrialized, in particular the agglomerations Cologne, Düsseldorf and Ruhr area. Here the Rhine flows through the largest conurbation in Germany, the Rhine-Ruhr region. Duisburg Inner Harbour (Duisport) and Dortmund Port are large industrial inland ports and serve as hubs along the Rhine and the German inland water transport system. The country is crossed by many canals like Rhine–Herne Canal (RHK), der Wesel-Datteln-Kanal (WDK), der Datteln-Hamm-Kanal (DHK) and Dortmund-Ems-Kanal (DEK) an important role for inland navigation.

Education
RWTH Aachen is one of Germany's leading universities of technology and was chosen by DFG as one of the German Universities of Excellence in 2007, 2012 and again in 2019. North Rhine-Westphalia is home to 14 universities and over 50 partly postgraduate colleges, with a total of over 742,000 students. Largest and oldest university is the University of Cologne (Universität zu Köln), founded in 1388 AD, since 2012 also one of Germany's eleven Universities of Excellence. University of Duisburg-Essen (Universität Duisburg-Essen), is also well known and is one of the largest universities in Germany.

Football

NRW is home to several football clubs of the Bundesliga including Bayer 04 Leverkusen, Borussia Dortmund, Borussia Mönchengladbach, 1. FC Köln and VfL Bochum and the 2. Bundesliga including Fortuna Düsseldorf, FC Schalke 04 and SC Paderborn 07 and the 3. Liga including Arminia Bielefeld, MSV Duisburg, Rot-Weiß Essen, Preußen Münster, Rot-Weiß Oberhausen, FC Viktoria Köln and SC Verl. Since the formal establishment of the German Bundesliga in 1963, Borussia Dortmund and Borussia Mönchengladbach have been the most successful teams in the state, with both winning five titles. 1. FC Köln won two titles, including the first in 1963. Before the league's establishment, North Rhine-Westfalian teams competed for the title of Deutscher Fußballmeister (German Football Champion). Here, FC Schalke 04 brought home seven titles, while Dortmund and Köln won an additional three and one title(s), respectively. Fortuna Düsseldorf and Rot-Weiß Essen have each been German Champion once. North Rhine-Westphalia has been a very successful footballing state having a combined total of 25 championships, fewer only than Bavaria.

Basketball
The state is also home to several professional basketball teams that currently either compete in the Basketball Bundesliga or ProA or have competed there in the past. These teams include Telekom Baskets Bonn, Bayer Giants Leverkusen, Paderborn Baskets, Uni Baskets Münster, VfL SparkassenStars Bochum, Phoenix Hagen and Alemannia Aachen.

Ice hockey
North Rhine-Westphalia is home to current and former DEL teams Düsseldorfer EG, Kölner Haie, Krefeld Pinguine, and Iserlohn Roosters.

title: North Rhine-Westphalia


text:
Electrode potential

In electrochemistry, electrode potential is the voltage of a galvanic cell built from a standard reference electrode and another electrode to be characterized. By convention, the reference electrode is the standard hydrogen electrode (SHE). It is defined to have a potential of zero volts. It may also be defined as the potential difference between the charged metallic rods and salt solution.

The electrode potential has its origin in the potential difference developed at the interface between the electrode and the electrolyte. It is common, for instance, to speak of the electrode potential of the M+/M redox couple.

Origin and interpretation
Electrode potential appears at the interface between an electrode and electrolyte due to the transfer of charged species across the interface, specific adsorption of ions at the interface, and specific adsorption/orientation of polar molecules, including those of the solvent.

In an electrochemical cell, the cathode and the anode have certain electrode potentials independently and the difference between them is the cell potential:

 * $$E_\text{cell} = E_\text{cathode} - E_\text{anode}.$$

The electrode potential may be either that at equilibrium at the working electrode ("reversible potential"), or a potential with a non-zero net reaction on the working electrode but zero net current ("corrosion potential", "mixed potential"), or a potential with a non-zero net current on the working electrode (like in galvanic corrosion or voltammetry). Reversible potentials can be sometimes converted to the standard electrode potential for a given electroactive species by extrapolation of the measured values to the standard state.

The value of the electrode potential under non-equilibrium depends on the nature and composition of the contacting phases, and on the kinetics of electrode reactions at the interface (see Butler–Volmer equation).

An operational assumption for determinations of the electrode potentials with the standard hydrogen electrode involves this reference electrode with hydrogen ion in an ideal solution having is "zero potential at all temperatures" equivalently to standard enthalpy of formation of hydrogen ion is also "zero at all temperatures".

Measurement
The measurement is generally conducted using a three-electrode setup (see the drawing):
 * 1) working electrode,
 * 2) counter electrode,
 * 3) reference electrode (standard hydrogen electrode or an equivalent).

In case of non-zero net current on the electrode, it is essential to minimize the ohmic IR-drop in the electrolyte, e.g., by positioning the reference electrode near the surface of the working electrode (e.g., see Luggin capillary), or by using a supporting electrolyte of sufficiently high conductivity. The potential measurements are performed with the positive terminal of the electrometer connected to the working electrode and the negative terminal to the reference electrode.

Sign conventions
Historically, two conventions for sign for the electrode potential have formed:
 * 1) convention "Nernst–Lewis–Latimer" (sometimes referred to as "American"),
 * 2) convention "Gibbs–Ostwald–Stockholm" (sometimes referred to as "European").

In 1953 in Stockholm IUPAC recognized that either of the conventions is permissible; however, it unanimously recommended that only the magnitude expressed according to the convention (2) be called "the electrode potential". To avoid possible ambiguities, the electrode potential thus defined can also be referred to as Gibbs–Stockholm electrode potential. In both conventions, the standard hydrogen electrode is defined to have a potential of 0 V. Both conventions also agree on the sign of $E$ for a half-cell reaction when it is written as a reduction.

The main difference between the two conventions is that upon reversing the direction of a half-cell reaction as written, according to the convention (1) the sign of $E$ also switches, whereas in the convention (2) it does not. The logic behind switching the sign of $E$ is to maintain the correct sign relationship with the Gibbs free energy change, given by $ΔG = –nFE$ where $n$ is the number of electrons involved and $F$ is the Faraday constant. It is assumed that the half-reaction is balanced by the appropriate SHE half-reaction. Since $ΔG$ switches sign when a reaction is written in reverse, so too, proponents of the convention (1) argue, should the sign of $E$. Proponents of the convention (2) argue that all reported electrode potentials should be consistent with the electrostatic sign of the relative potential difference.

Potential difference of a cell assembled of two electrodes
Potential of a cell assembled of two electrodes can be determined from the two individual electrode potentials using

 * $$\Delta V_\text{cell} = E_\text{red,cathode} - E_\text{red,anode}$$ however, it depends.

or, equivalently,

 * $$\Delta V_\text{cell} = E_\text{red,cathode} + E_\text{oxy,anode}.$$

This follows from the IUPAC definition of the electric potential difference of a galvanic cell, according to which the electric potential difference of a cell is the difference of the potentials of the electrodes on the right and the left of the galvanic cell. When $ΔV_{cell}$ is positive, then positive electrical charge flows through the cell from the left electrode (anode) to the right electrode (cathode).

title: Electrode potential


text:
Erich Hückel

Erich Armand Arthur Joseph Hückel (August 9, 1896, Berlin – February 16, 1980, Marburg) was a German physicist and physical chemist. He is known for two major contributions:
 * The Debye–Hückel theory of electrolytic solutions
 * The Hückel method of approximate molecular orbital (MO) calculations on π electron systems.

Hückel was born in the Charlottenburg suburb of Berlin. He studied physics and mathematics from 1914 to 1921 at the University of Göttingen.

On receiving his doctorate, he became an assistant at Göttingen, but soon became an assistant to Peter Debye at Zürich. It was there that he and Debye developed their theory (the Debye–Hückel theory, in 1923) of electrolytic solutions, elucidating the behavior of strong electrolytes by considering interionic forces, in order to account for their electrical conductivity and their thermodynamic activity coefficients.

After spending 1928 and 1929 in England and Denmark, working briefly with Niels Bohr, Hückel joined the faculty of the Technische Hochschule in Stuttgart. In 1935, he moved to Phillips University in Marburg, where he finally was named Full Professor a year before his retirement 1961. He was a member of the International Academy of Quantum Molecular Science.

Theories of unsaturated organic molecules
Hückel is most famous for developing the Hückel method of approximate molecular orbital (MO) calculations on π electron systems, a simplified quantum-mechanical method to deal with planar unsaturated organic molecules. In 1930 he proposed a σ/π separation theory to explain the restricted rotation of alkenes (compounds containing a C=C double bond). This model extended a 1929 interpretation of the bonding in triplet oxygen by Lennard-Jones. According to Hückel, only the ethene σ bond is axially symmetric about the C-C axis, but the π bond is not; this restricts rotation. In 1931 he generalized his analysis by formulating both valence bond (VB) and molecular orbital (MO) descriptions of benzene and other cycloconjugated hydrocarbons.

Although undeniably a cornerstone of organic chemistry, Hückel's concepts were undeservedly unrecognized for two decades. Pauling and Wheland characterized his approach as "cumbersome" at the time, and their competing resonance theory was relatively easier to understand for chemists without fundamental physics background, even if they couldn't grasp the concept of quantum superposition and confused it with tautomerism. His lack of communication skills contributed: when Robert Robinson sent him a friendly request, he responded arrogantly that he is not interested in organic chemistry.

The famous Hückel 4n+2 rule for determining whether ring molecules composed of C=C bonds would show aromatic properties was first stated clearly by Doering in a 1951 article on tropolone. Tropolone had been recognised as an aromatic molecule by Dewar in 1945.

In 1936, Hückel developed the theory of π-conjugated biradicals (non-Kekulé molecules). The first example, known as the Schlenk–Brauns hydrocarbon, had been discovered in the same year. The credit for explaining such biradicals is usually given to Christopher Longuet-Higgins in 1950.

In 1937, Hückel refined his MO theory of pi electrons in unsaturated organic molecules. This is still used occasionally as an approximation, though the more precise PPP Pariser–Parr–Pople method succeeded it in 1953. "Extended Hückel MO theory" (EHT) applies to both sigma and pi electrons, and has its origins in work by William Lipscomb and Roald Hoffmann for nonplanar molecules in 1962.

Poem about Schrödinger
According to Felix Bloch, Erich Hückel "incited and helped" the students at the University of Zurich to write poems about their great professors. The poem about Erwin Schrödinger went like this:

Gar Manches rechnet Erwin schon

Mit seiner Wellenfunktion.

Nur wissen möcht' man gerne wohl

Was man sich dabei vorstell'n soll.

It was freely translated by Felix Bloch:

Erwin with his psi can do

Calculations quite a few.

But one thing has not been seen:

Just what does psi really mean?

Awards

 * 1965 Otto Hahn Prize for Chemistry and Physics

title: Erich Hückel