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The Church of Jesus Christ of Latter-day Saints

The Church of Jesus Christ of Latter-day Saints, informally known as the LDS Church or Mormon Church, is the largest Latter Day Saint denomination, tracing its roots to its founding by Joseph Smith during the Second Great Awakening. The church is headquartered in the United States in Salt Lake City, Utah and has established congregations and built temples worldwide. According to the church, as of 2023, it has over 17.2 million members of which over 6.8 million live in the U.S. The church also reports over 99,000 volunteer missionaries and 350 temples in total. As of 2020, the church was the religious group in the United States with the fifth largest shares of adherents.

The church was founded as the Church of Christ in western New York, in 1830 by Smith. Under Smith's leadership, the church's headquarters moved successively to Ohio, Missouri, and Illinois. After Smith's 1844 death and a resultant succession crisis, the majority of his followers sided with Brigham Young, who led the church to its current headquarters in Salt Lake City. Young and his successors continued the church's growth, first throughout the Intermountain West, and more recently as a national and international organization.

Church theology is restorationist and nontrinitarian; the church strongly identifies as Christian including a belief in the doctrine of salvation through Jesus Christ and his substitutionary atonement on behalf of mankind. It is often included in the lists of larger Christian denominations, though some Catholics, Mainline Protestants and Evangelicals have considered the church to be distinct and separate from mainstream Christianity due to doctrinal differences. The church has an open canon of four scriptural texts: the Holy Bible, the Book of Mormon, the Doctrine and Covenants (D&C), and the Pearl of Great Price. Other than the Bible, the majority of the church canon consists of material the church's members believe to have been revealed by God to Joseph Smith, including commentary and exegesis about the Bible, texts described as lost parts of the Bible, and other works believed to be written by ancient prophets, including the Book of Mormon.

Members of the church, known as Latter-day Saints or informally as Mormons, believe that the church president is a modern-day "prophet, seer, and revelator" and that Jesus Christ, under the direction of God the Father, leads the church by revealing his will and delegating his priesthood keys to its president. The president heads a hierarchical structure descending from areas to stakes and wards. The church has a volunteer clergy at the local and regional levels; wards are led by bishops, who are drawn from the membership of the wards themselves. Male members may be ordained to the priesthood, provided they are living the standards of the church. Women are not ordained to the priesthood but occupy leadership roles in some church organizations.

Both men and women may serve as missionaries. The church maintains a large missionary program that proselytizes and conducts humanitarian services worldwide. The church also funds and participates in humanitarian projects independent of its missionary efforts. Members adhere to church laws of sexual purity, health, fasting, and Sabbath observance, and contribute ten percent of their income to the church in tithing. The church teaches ordinances through which adherents make covenants with God, including baptism, confirmation, the sacrament, priesthood ordination, endowment and celestial marriage.

The church has been criticized throughout its history. Modern criticism includes disputes over the church's historical claims, treatment of minorities, and finances. The church's practice of polygamy was controversial until it was curtailed in 1890 and officially rescinded in 1904.

Beginnings
Joseph Smith formally organized the church as the Church of Christ, on April 6, 1830, in western New York; the church's name was later changed to the Church of Jesus Christ of Latter Day Saints. Initial converts were drawn to the church in part because of the newly published Book of Mormon, a self-described chronicle of indigenous American prophets that Smith said he had translated from golden plates.

Smith intended to establish the New Jerusalem in North America, called Zion. In 1831, the church moved to Kirtland, Ohio, and began establishing an outpost in Jackson County, Missouri,   where Smith planned to eventually move the church headquarters. However, in 1833, Missouri settlers violently expelled the Latter Day Saints from Jackson County. The church attempted to recover the land through a paramilitary expedition, but did not succeed. Nevertheless, the church flourished in Kirtland as Smith published new revelations and the church built the Kirtland Temple, culminating in a dedication of the building similar to the day of Pentecost. The Kirtland era ended in 1838, after a financial scandal rocked the church and caused widespread defections. Smith regrouped with the remaining church in Far West, Missouri, but tensions soon escalated into violent conflicts with the old Missouri settlers. Believing the Latter Day Saints to be an insurrection, the Missouri governor ordered that they be "exterminated or driven from the State". In 1839, the Latter Day Saints converted a swampland on the banks of the Mississippi River into Nauvoo, Illinois, which became the church's new headquarters. Nauvoo grew rapidly as missionaries sent to Europe and elsewhere gained new converts who then flooded into Nauvoo. Meanwhile, Smith introduced polygamy to his closest associates. He also established ceremonies, which he stated the Lord had revealed to him, to allow righteous people to become gods in the afterlife, and a secular institution to govern the Millennial kingdom. He also introduced the church to a full accounting of his First Vision, in which he claimed that two heavenly "personages" appeared to him at age 14. This vision would come to be regarded by the LDS Church as the most important event in human history since the resurrection of Jesus.

On June 27, 1844, Smith and his brother, Hyrum, were killed by a mob in Carthage, Illinois, while being held on charges of treason. Because Hyrum was Joseph's designated successor, their deaths caused a succession crisis,  and Brigham Young assumed leadership over a majority of the church's membership. Young had been a close associate of Smith's and was the president of the Quorum of the Twelve Apostles in Smith's church.

Other splinter groups followed other leaders around this time. These groups have no affiliation with the LDS Church, however they share a common heritage in their early church history. Collectively, they are called the Latter Day Saint movement. The largest of these smaller groups is the Community of Christ, based in Independence, Missouri, followed by the Church of Jesus Christ, based in Monongahela, Pennsylvania. Like the LDS Church, these faiths believe in Joseph Smith as a prophet and founder of their religion. They also accept the Book of Mormon, and most accept at least some version of the Doctrine and Covenants. However, they tend to disagree to varying degrees with the LDS Church concerning doctrine and church leadership.

Pioneer era
For two years after Smith's death, conflicts escalated between Mormons and other Illinois residents. Brigham Young led his followers, later called the Mormon pioneers, westward to Nebraska and then in 1847 on to what later became the Utah Territory, which at the time had been part of the indigenous lands of the Ute, Goshute, and Shoshone nations, and claimed by Mexico until 1848. Around 80,000 settlers arrived between 1847 and 1869, who then branched out and colonized a large region now known as the Mormon Corridor. Meanwhile, efforts to globalize the church began in earnest around this time, with missionaries being sent off to the Sandwich Islands (present-day Hawaii), India, Chile, Australia, China, South Africa, and all over Europe.

Young incorporated the LDS Church as a legal entity, and initially governed both the church and the state as a theocratic leader. He also publicized the practice of plural marriage in 1852. Modern research suggests that around 20 percent of Mormon families may have participated in the practice. By 1857, tensions had again escalated between Mormons and other Americans, largely as a result of accusations involving polygamy and the theocratic rule of the Utah Territory by Young. The Utah Mormon War ensued from 1857 to 1858, which resulted in the relatively peaceful invasion of Utah by the United States Army. The most notable instance of violence during this conflict was the Mountain Meadows massacre, in which leaders of a local Mormon militia ordered the massacre of a civilian emigrant party who was traveling through Utah during the escalating military tensions. After the massacre was discovered, the church became the target of significant media criticism for it.

After the Army withdrew, Young agreed to step down from power and be replaced by a non-Mormon territorial governor, Alfred Cumming. Nevertheless, the LDS Church still wielded significant political power in the Utah Territory. Coterminously, tensions between Mormon settlers and indigenous tribes continued to escalate as settlers began colonizing a growing area of tribal lands. While Mormons and indigenous peoples made attempts at peaceful coexistence, skirmishes ensued from about 1849 to 1873 culminating in the armed conflicts of Walkara's War, the Bear River Massacre, and the Black Hawk War.

After Young's death in 1877, he was followed in the church presidency by John Taylor and Wilford Woodruff successively, who resisted efforts by the United States Congress to outlaw Mormon polygamous marriages. In 1878, the United States Supreme Court, in Reynolds v. United States, decreed that "religious duty" to engage in plural marriage was not a valid defense to prosecutions for violating state laws against polygamy. Conflict between Mormons and the U.S. government escalated to the point that, in 1890, Congress disincorporated the LDS Church and seized most of its assets. Soon thereafter, Woodruff issued a manifesto that officially suspended the performance of new polygamous marriages in the United States. Relations with the United States markedly improved after 1890, such that Utah was admitted as a U.S. state in 1896. Relations further improved after 1904, when church president Joseph F. Smith again disavowed polygamy before the United States Congress and issued a "Second Manifesto", calling for all plural marriages in the church to cease. Eventually, the church adopted a policy of excommunicating its members found practicing polygamy. Some fundamentalist groups with relatively small memberships have broken off and continue to practice polygamy, but the Church distances itself from them.

Modern times
During the 20th century, the church grew substantially and became an international organization. In 2000, the church reported over 60,000 missionaries and global church membership stood at just over 11 million. Nominal worldwide membership surpassed 16 million in 2018. Slightly under half of church membership lives within the United States. Academics have called the denomination a Restorationist church, a new religious movement, and a potential world religion.

The church has become a strong proponent of the nuclear family and at times played a prominent role in political matters, including opposition to MX Peacekeeper missile bases in Utah and Nevada, the Equal Rights Amendment, legalized gambling, same-sex marriage, and physician-assisted death.

A number of official changes have taken place to the organization during the modern era. In 1978, the church reversed its previous policy of excluding black men of African descent from the priesthood, which had been in place since 1852; members of all races can now be ordained to the priesthood. Also, since the early 1900s, the church has instituted a Priesthood Correlation Program to centralize church operations and bring them under a hierarchy of priesthood leaders. During the Great Depression, the church also began operating a church welfare system, and it has conducted humanitarian efforts in cooperation with other religious organizations such as Catholic Relief Services, as well as secular organizations like Care International. The church has supported its members serving in the armed forces during World Wars I and II, both in the United States and internationally. From 1913 to 2020 the church was a major sponsor of Scouting programs for boys, particularly in the United States. The LDS Church was the largest chartered organization in the Boy Scouts of America, but in 2020, the church ended its relationship with the BSA and began an alternate, religion-centered youth program, which replaced all other youth programs.

During the second half of the 20th century and beginnings of the 21st, the church has responded to various challenges to its doctrine and authority. Challenges have included rising secularization, challenges to the correctness of the translation of the Book of Abraham,  and primary documents forged by Mark Hofmann purporting to contradict important aspects of official early church history. The church's positions regarding women, black people, and homosexuality have all been publicly criticized during this timeframe.

Nature of God
LDS Church theology includes the belief in a Godhead composed of God the Father, his son, Jesus Christ, and the Holy Ghost as three separate persons who share a unity of purpose or will; however, they are viewed as three distinct beings. This is in contrast with the predominant Christian view, which holds that God is a Trinity of three distinct persons in one essence. The Latter-day Saint conception of the Godhead is similar to what contemporary Christian theologians call social trinitarianism. The church also believes that God the Father and his son, Jesus Christ, are separate beings with bodies of flesh and bone, while the Holy Ghost lacks such a physical body.

According to statements by church leaders, God sits at the head of the human family and is married to a Heavenly Mother, who is the mother of human spirits. However, church leaders have also categorically discouraged prayers to her and counseled against speculation regarding her.

Jesus Christ
Church members believe in Jesus Christ as the literal Son of God and Messiah, his crucifixion as a conclusion of a sin offering, and his subsequent resurrection. However, Latter-day Saints reject the ecumenical creeds and the definition of the Trinity. Jesus is also seen as the elder brother of all who live in this world. The church teaches that Jesus performed a substitutionary atonement; in contrast with other Christian denominations, the church teaches this atonement began in the garden of Gethsemane and continued to his crucifixion (rather than the orthodox belief that the crucifixion alone was the physical atonement). The church also teaches that Jesus appeared to other peoples after his death, including spirits of the dead in the spirit world,  and indigenous Americans.

The church also teaches that Jesus is the true founder and leader of the church itself. The physical establishment of the church by Smith in 1830 is seen as simply the reestablishment of the same primitive church that existed under Jesus and his Apostles. Similarly, the church teaches that Jesus leads the church presently through its apostles and prophets, especially its current president.

Comparison with Nicene Christianity
The LDS Church shares various teachings with other branches of Christianity. These include a belief in the Bible, the divinity of Jesus, his atonement and resurrection, and a form of apostolic succession.

Nevertheless, the LDS Church differs from other churches within contemporary Christianity in other ways. Differences between the LDS Church and most of traditional Christianity include disagreement about the nature of God, belief in a theory of human salvation that includes three heavens, a doctrine of exaltation which includes the ability of humans to become gods and goddesses in the afterlife, a belief in continuing revelation and an open scriptural canon, and unique ceremonies performed privately in temples, such as the endowment and sealing ceremonies. A number of major Christian denominations view the LDS Church as standing apart from creedal Christianity. However, church members self-identify as Christians.

The faith itself views other modern Christian faiths as having departed from true Christianity by way of a general apostasy and maintains that it is a restoration of 1st-century Christianity and the only true and authorized Christian church. Church leaders assert it is the only true church and that other churches do not have the authority to act in Jesus' name.

Cosmology and plan of salvation
The church's cosmology and plan of salvation include the doctrines of a pre-existence, an earthly mortal existence, three degrees of heaven and exaltation.

According to these doctrines, every human spirit is a spiritual child of a Heavenly Father and each has the potential to continue to learn, grow, and progress in the eternities, eventually achieving eternal life, which is to become one with God in the same way that Jesus Christ is one with the Father, thus allowing the children of God to become divine beings—that is, gods—themselves. This view on the doctrine of theosis is also referred to as becoming a "joint-heir with Christ". The process by which this is accomplished is called exaltation, a doctrine which includes the reunification of the mortal family after the resurrection and the ability to have spirit children in the afterlife and inherit a portion of God's kingdom. To obtain this state of godhood, the church teaches that one must have faith in Jesus Christ, repent of his or her sins, strive to keep the commandments faithfully, and participate in ordinances.

According to LDS Church theology, men and women may be sealed to one another so that their marital bond continues into the eternities. Children may also be sealed to their biological or adoptive parents to form permanent familial bonds, thus allowing all immediate and extended family relations to endure past death. The most significant LDS ordinances may be performed via proxy in behalf of those who have died, such as baptism for the dead. The church teaches that all will have the opportunity to hear and accept or reject the gospel of Jesus Christ, either in this life or the next.

Within church cosmology, the fall of Adam and Eve is seen positively. The church teaches that it was essential to allow humankind to experience separation from God, to exercise full agency in making decisions for their own happiness.

Restorationism
The LDS Church teaches that, subsequent to the death of Jesus and his original apostles, his church, along with the authority to act in Jesus Christ's name and the church's attendant spiritual gifts, were lost, due to a combination of external persecutions and internal heresies. The restoration—as represented by the church begun by Joseph Smith—refers to a return of the authentic priesthood power, spiritual gifts, ordinances, living prophets and revelation of the primitive Church of Christ. This restoration is associated with a number of events which are understood to have been necessary to re-establish the early Christian church found in the New Testament, and to prepare the earth for the Second Coming of Jesus. In particular, Latter-day Saints believe that angels appeared to Joseph Smith and a limited number of his associates, and bestowed various priesthood authorities on them.

Leadership

The church is led by a president, who is considered a "prophet, seer, and revelator." Within the church, he is referred to as "the Prophet" or the "President of the Church." He is considered the only person who is authorized to receive revelation from God on behalf of the whole world or entire church. As such, the church teaches that he is essentially infallible when speaking on behalf of God—although the exact circumstances when his pronouncements should be considered authoritative are debated within the church. In any case, modern declarations with broad doctrinal implications are often issued by joint statement of the First Presidency; they may be joined by the Quorum of the Twelve Apostles as well. Church members believe Joseph Smith was the first modern-day prophet.

Normally, the Prophet and two other ordained apostles he chooses as counselors form the First Presidency, the presiding body of the church; twelve other apostles form the Quorum of the Twelve Apostles. When a president dies, his successor is chosen from the remaining apostles, and is invariably the longest-tenured of the group. Apostles are chosen by the church president after the death of an existing apostle. Following the death of church president Thomas S. Monson on January 2, 2018, senior apostle Russell M. Nelson was announced as president on January 16.

The general authorities of the church consist of the First Presidency, Quorum of the Twelve Apostles, first two Quorums of Seventy and the Presiding Bishopric. And under the leadership of the general officers are five organizations: the Relief Society, Sunday School, Young Women, Young Men, and Primary. Women serve as presidents and counselors in the presidencies of the Relief Society, Young Women, and Primary, while men serve as presidents and counselors of the Sunday School and Young Men.

Home and family
The church and its members consider marriage and family highly important, with emphasis placed on large, nuclear families. In 1995, the church's First Presidency and Quorum of the Twelve issued "The Family: A Proclamation to the World", which asserts the importance of a heterosexual, nuclear family. Its intended audience was not only for its own members but to "responsible citizens and officers of government everywhere". The proclamation defined marriage as a union between one man and one woman and stated that the family unit is "central to the Creator's plan for the eternal destiny of His children." The document further says that "gender is an essential characteristic of individual premortal, mortal, and eternal identity and purpose," that the father and mother have differing roles as "equal partners" in raising children, that "children are entitled to birth within the bonds of matrimony", and that successful marriages and happy families are most likely established when founded upon the teachings of Jesus Christ. The proclamation also promotes specific roles essential to maintaining the strength of the family unit—the traditional roles of a husband and father as the family's breadwinner and those of a wife and mother as a nurturing caregiver. Nonetheless, it acknowledges that "circumstances may necessitate individual adaptation" and that spouses are "obligated to help one another as equal partners" in fulfilling those roles. It also charges both parents with the duties of childrearing. It concludes by inviting its audience to "promote those measures designed to maintain and strengthen the family as the fundamental unit of society". Senior church leaders have continued to emphasize conservative teachings on marriage and gender to the present time.

LDS Church members are encouraged to set aside one evening each week, typically Monday, to spend together in "Family Home Evening" (FHE), which typically consists of gathering as a family to study the faith's gospel principles, and other family activities. Daily family prayer is also encouraged.

Sources of doctrine

The theology of the LDS Church consists of a combination of biblical doctrines with modern revelations and other commentary by LDS leaders, particularly Joseph Smith. The most authoritative sources of theology are the faith's canon of four religious texts, called the "standard works". Included in the standard works are the Bible, the Book of Mormon, the D&C and the Pearl of Great Price.

The Book of Mormon is a foundational sacred book for the church; the terms "Mormon" and "Mormonism" come from the book itself. The LDS Church teaches that the Angel Moroni told Smith about golden plates containing the record, guided him to find them buried in the Hill Cumorah, and provided him the means of translating them from Reformed Egyptian. It claims to give a history of the inhabitants from a now-extinct society living on the American continent and their distinct Judeo-Christian teachings. The Book of Mormon is very important to modern Latter-day Saints, who consider it the world's most correct text.

The Bible, also part of the church's canon, is believed to be the word of God—subject to an acknowledgment that its translation may be incorrect, or that authoritative sections may have been lost over the centuries. Most often, the church uses the Authorized King James Version. Two extended portions of the Joseph Smith Translation of the Bible have been canonized and are thus considered authoritative. Additionally, over 600 of the more doctrinally significant verses from the translation are included as excerpts in the current LDS Church edition of the Bible. Other revelations from Smith are found in the D&C, and in the Pearl of Great Price. Another source of authoritative doctrine is the pronouncements of the current Apostles and members of the First Presidency. The church teaches that the First Presidency and the Quorum of Twelve Apostles are prophets and that they are therefore authorized teachers of God's word.

In addition to doctrine given by the church as a whole, individual members of the church believe that they can also receive personal revelation from God in conducting their lives, and in revealing truth to them, especially about spiritual matters. Generally, this is said to occur through thoughts and feelings from the Holy Ghost, in response to prayer. Similarly, the church teaches its members may receive individual guidance and counsel from God through blessings from priesthood holders. In particular, patriarchal blessings are considered special blessings that are received only once in the recipient's life, which are recorded, transcribed, and archived.

Rituals
In the church, an ordinance is a sacred rite or ceremony that has spiritual and symbolic meanings, and acts as a means of conveying divine grace. Ordinances are physical acts which signify or symbolize an underlying spiritual act; for some ordinances, the spiritual act is the finalization of a covenant between the ordinance recipient and God. Ordinances are generally performed under priesthood authority.

The ordinance of baptism is believed to bind its participant to Jesus Christ, who saves them in their imperfection if they continually keep their promises to him. Baptism is performed by immersion, and is typically administered to children starting at age eight.

Church members believe that through the ordinances of temple sealing and temple endowment, anyone can reach the highest level of salvation in the celestial kingdom and eternally live in God's presence, continue as families, become gods, create worlds, and make spirit children over whom they will govern.

Other ordinances performed in the church include confirmation, the sacrament (analogous to the Eucharist or holy communion), and priesthood ordination.

Diet and health
The LDS Church asks its members to adhere to a dietary code called the Word of Wisdom, in which they abstain from the consumption of alcohol, coffee, tea, tobacco, and illicit or harmful substances. The Word of Wisdom also encourages the consumption of herbs and grains along with the moderate consumption of meat.

When Joseph Smith published the Word of Wisdom in 1833, it was considered only advice; violation did not restrict church membership. During the 1890s, though, church leaders started emphasizing the Word of Wisdom more. In 1921, church president Heber J. Grant made obeying the Word of Wisdom a requirement to engage in worship inside of the faith's temples. From that time, church leadership has emphasized the forbidding of coffee, tea, tobacco, and alcohol, but not the other guidelines concerning meat, grains, and herbs. In 2019, the church further clarified through its New Era magazine that the usage of marijuana and opioids is prohibited except as prescribed by a competent physician for medical purposes.

Sexuality
Church members are expected to follow a moral code called the law of chastity, which prohibits adultery, homosexual behavior, and sexual relations before or outside of marriage. As part of the law of chastity, the church strongly opposes pornography, and considers masturbation an immoral act. Law of chastity violations can be grounds for church discipline; resulting penalties may include having access to the temple and sacrament revoked, as well as withdrawal of church membership. The church discourages romantic dating until around the age of 16.

Tithing and other donations
Church members are expected to donate one-tenth of their income to support the operations of the church. After initially relying on a communal lifestyle known as the law of consecration throughout most of the 1830s, the church created the law of tithing in July 1838 when the membership was concentrated in Missouri. Church members would frequently tithe by giving ten percent of their livestock and produce; nowadays donations are generally done with money.

Annual donations were estimated to total $7 billion to $33 billion USD donated in 2012 (equivalent to $ billion to $ billion in ). In order to qualify for participation in temple ordinances (which Latter-day Saints believe are necessary for their salvation), paying a full tithe is a requirement, regardless of one's temporal circumstances. Members are also encouraged to fast (abstain from food and drink) on the first Sunday of each month for two consecutive meals. They donate at least the cost of the two skipped meals of the fast as a "fast offering", which the church uses to assist people in need and expand its humanitarian efforts.

Local leadership is not paid, and is expected to tithe as well. Full-time missionaries, however, are not expected to pay tithing as they are usually paying to be a missionary.

Missionary service

Serving a two-year, full-time proselytizing mission is expected for all able-bodied LDS young men. Missionaries do not choose where they serve or the language in which they will proselytize, and are expected to fund their missions themselves or with the aid of their families. Prospective male missionaries must be between the ages of 18 and 25 and have completed secondary school. All proselytizing missionaries are organized geographically into administrative areas called missions. The efforts in each mission are directed by an older adult male mission president. As of July 2020, there were 407 missions of the church.

Although missionary service is expected for men, it is not compulsory and is not required to retain church membership. Unmarried women between the ages of 19 and 29 may also serve as missionaries, generally for a term of 18 months. Retired couples are also encouraged to serve missions, and may serve from 6–23 months terms. Unlike younger missionaries, these senior missionaries may serve in non-proselytizing capacities such as humanitarian aid workers or family history specialists. Other men and women who desire to serve a mission, but may not be able to perform full-time service in another state or country due to health issues, may serve in a non-proselytizing mission. They might assist at Temple Square in Salt Lake City or aid in the seminary system in schools.

Sabbath day observance
Church members are expected to set aside Sundays as a day of rest and worship. Typically, weekly worship meetings occur solely on Sundays. Shopping and recreation are discouraged on Sundays as well.

Weekly meetings
Meetings for worship and study are held at meetinghouses, which are typically utilitarian in character. The main focus of Sunday worship is the Sacrament meeting, where the sacrament is passed to church members; sacrament meetings also include prayers, the singing of hymns by the congregation or choir, and impromptu or planned sermons by church members. Also included in weekly meetings are times for Sunday School, or separate instructional meetings based on age and gender, including the Relief Society for women.

Church congregations are organized geographically. Members are generally expected to attend the congregation within their assigned geographical area; however, some geographical areas also provide separate congregations for young single adults, older single adults, or for speakers of alternate languages. For Sunday services, the church is grouped into either larger congregations known as wards, or smaller congregations known as branches. Regional church organizations, encompassing multiple congregations, include stakes, missions, districts and areas.

The church's Young Men and Young Women organizations meet at the meetinghouse once a week, on a day other than Sunday, where the youth participate in activities.

Temple worship

In LDS theology, a temple is considered to be a holy building, dedicated as a "House of the Lord" and held as more sacred than a typical meetinghouse or chapel. In temples, church members participate in ceremonies that are considered the most sacred in the church, including marriage, and an endowment ceremony that includes a washing and anointing, receiving a temple garment, and making covenants with God. Baptisms for the dead—as well as other temple ordinances on behalf of the dead —are performed in the temples as well.

Temples are considered by church members to be the most sacred structures on earth, and as such, operating temples are not open to the public. Then after the temple is dedicated, permission to enter is reserved only for church members who pass periodic interviews with ecclesiastical leaders and receive a special recommendation card, called a temple recommend, that they present upon entry. Church members are instructed not to share details about temple ordinances with non-members or even converse about them outside the temple itself. As of May 2023, there are 177 operating temples worldwide.

In order to perform ordinances in temples on behalf of deceased family members, the church emphasizes genealogical research, and encourages its lay members to participate in genealogy. It operates FamilySearch, the largest genealogical organization in the world.

Conferences
Twice each year (the first weekend of April and October), general authorities and general officers address the worldwide church through general conference. General conference sessions are translated into as many as 80 languages and are broadcast from the 21,000-seat Conference Center in Salt Lake City. During this conference, church members formally acknowledge, or "sustain", the First Presidency and Quorum of the Twelve Apostles as prophets, seers, and revelators.

Individual stakes also hold formal conferences within their own boundaries biannually; wards hold conferences annually.

Name and legal entities
The church teaches that it is a continuation of the Church of Christ restored in 1830 by Joseph Smith. This original church underwent several name changes during the 1830s, being changed to "The Church of the Latter Day Saints", "The Church of Jesus Christ", "The Church of God", "The Church of Christ of Latter Day Saints" and "The Church of Jesus Christ of Latter Day Saints" (by an 1838 revelation). Finally, after Smith died, Brigham Young and the largest body of Smith's followers incorporated the church in 1851 by legislation of the Utah Territory under the name "The Church of Jesus Christ of Latter-day Saints", which included a hyphenated "Latter-day" and a British-style lower-case d.

Common informal names for the church include the LDS Church, the Mormon Church, and the Latter-day Saints Church. The church requests that the official name be used when possible or, if necessary, shortened to "the Church" or "the Church of Jesus Christ". In August 2018, church president Russell M. Nelson asked members of the church and others to cease using the terms "LDS", "Mormon" and "Mormonism" to refer to the church, its membership, or its belief system and instead to call the church by its full and official name. Subsequent to this announcement, the church's premier vocal ensemble, the Mormon Tabernacle Choir, was officially renamed and became the "Tabernacle Choir at Temple Square". Reaction to the name change policy has been mixed.

Legally, the church currently functions as a corporation sole, incorporated in Utah.

Intellectual Reserve is a nonprofit corporation wholly owned by the church, which holds the church's intellectual property, such as copyrights, trademarks, and other media.

Priesthood hierarchy and church service
The LDS Church is organized in a hierarchical priesthood structure administered by its male members. Members of the church-wide leadership are called general authorities. They exercise both ecclesiastical and administrative leadership over the church and direct the efforts of regional leaders down to the local level. General authorities, general officers and mission presidents work full-time for the church, and typically receive stipends from church funds or investments. As well as speaking in general conference, general authorities and general officers speak to church members in local congregations throughout the world; they also speak to youth and young adults in broadcasts and at the Church Educational System (CES) schools, such as Brigham Young University (BYU). Local congregations are typically led by bishops, who perform similar functions to pastors in the Protestant tradition, or parish priests in the Roman Catholic Church.

All males who are living the standards of the church are generally considered for the priesthood and are ordained to the priesthood as early as age 11. Ordination occurs by a ceremony where hands are laid on the head of the one ordained. The priesthood is divided into an order for young men aged 11 years and older (called the Aaronic priesthood) and an order for men 18 years of age and older (called the Melchizedek priesthood). Additional authorities within the priesthood – called priesthood keys – are extended to holders of certain church leadership callings.

Some church leaders and scholars have spoken of women holding or exercising priesthood power. However, women are not formally ordained to the priesthood, and they do not participate in public functions administered by the priesthood—such as passing the Sacrament, giving priesthood blessings, or holding leadership positions over mixed-gender congregations. Since 2013, the Ordain Women organization has sought formal priesthood ordination for women. In 2019, church leadership authorized LDS women to serve as witnesses for baptisms, a ceremonial role previously reserved for male priesthood holders.

Each active church member is expected to receive a calling, or position of assigned responsibility within the church. Church members are expected to neither ask for specific callings, nor decline callings that are extended to them by their leaders. Leadership positions in the church's various congregations are filled through the calling system, and the vast majority of callings are filled on a volunteer basis. Members volunteer general custodial work for local church facilities.

Programs and organizations

The church operates several programs and organizations in the fields of proselytizing, education, and church welfare such as LDS Humanitarian Services. Many of these organizations and programs are coordinated by the Priesthood Correlation Program, which is designed to provide a systematic approach to maintain worldwide consistency, orthodoxy, and control of the church's ordinances, doctrines, organizations, meetings, materials, and other programs and activities.

The church also operates CES, which includes BYU, BYU–Idaho, BYU–Hawaii, and Ensign College. The church also operates Institutes of Religion near the campuses of many colleges and universities. For high-school aged youth, the church operates a four-year Seminary program, which provides religious classes for students to supplement their secular education. The church also sponsors a low-interest educational loan program known as the Perpetual Education Fund, which provides educational opportunities to students from developing nations. The church's welfare system, initiated in 1930 during the Great Depression, provides aid to the poor. Leaders ask members to fast once a month and donate the money they would have spent on those meals to help the needy, in what is called a fast offering. Money from the program is used to operate Bishop's storehouses, which package and store food at low cost. Distribution of funds and food is administered by local bishops. The church also distributes money through its Philanthropies division to disaster victims worldwide.

Other church programs and departments include Family Services, which provides adoption resource referrals, marital and family counseling, psychotherapy, and addiction counseling; the LDS Church History Department, which collects church history and records; and the Family History Department, which administers the church's large family history efforts, including FamilySearch, the world's largest family history library and organization. Other facilities owned and operated by the church include Temple Square, the Church Office Building, the Church Administration Building, the Church History Library and the Granite Mountain Records Vault.

Finances
Since 1941, the church has been classified by the IRS as a 501(c)(3) organization and is therefore tax-exempt. Donations are tax-deductible in the United States. The church has not released church-wide financial statements since 1959. In the absence of official statements, people interested in knowing the church's financial status and behavior, including both members of the church and people outside the church, have attempted to estimate or guess.

In 1997, Time magazine called the LDS Church one of the world's wealthiest churches per capita. The church has stated that its for-profit, non-profit, and educational subsidiary entities are all audited by professionals independent from other church entities. The church receives significant funds from tithes and fast offerings. It has been estimated that during the 2010s its net worth increased by about $15 billion per year ($ billion in ), and by $22 billion during the COVID-19 pandemic. According to a 2020 estimate by The Wall Street Journal, the LDS Church's investment fund had a net worth of around $100 billion.

The church's assets are held in a variety of holding companies, subsidiary corporations, and for-profit companies including: Bonneville International, KSL, Deseret Book Company, and holding companies for cattle ranches and farms in at least 12 U.S. States, Canada, New Zealand, and Argentina. Also included are banks and insurance companies, hotels and restaurants, real estate development, forestry and mining operations, and transportation and railway companies. Investigative journalism from the Truth & Transparency Foundation in 2022 suggests the church may be the owner of the most valuable real estate portfolio in the United States, with a minimum market value of $15.7 billion. The church has also invested in for-profit business and real estate ventures such as City Creek Center. The church-owned investment firm Ensign Peak Advisors publicly reports management of $37.8 billion of financial securities, as of 2020. By summer 2023 assets including "international shares as well as bonds, hybrid investments, real estate and major stakes in private equity" were estimated to exceed $163 billion.

Culture
Due to the differences in lifestyle promoted by church doctrine and history, members of the church have developed a distinct culture. It is primarily concentrated in the Mormon corridor of the Intermountain West.

Many of the church's more distinctive practices follow from their adherence to the Word of Wisdom—which includes abstinence from tobacco, alcohol, coffee, and tea—and their observance of Sabbath-day restrictions on recreation and shopping. Common, distinctive cuisine includes funeral potatoes and Jello salad. Cultural taboos exist on piercings and tattoos and the church counsels against the use of crosses as symbols of worship.

Media and arts
LDS-themed media includes cinema, fiction, websites, and graphical art such as photography and paintings. The church owns a chain of bookstores called Deseret Book, which provide a channel through which publications are sold; church leaders have authored books and sold them through the publishing arm of the bookstore. BYU TV, the church-sponsored television station, also airs on several networks. The church also produces several pageants annually depicting various events of the primitive and modern-day church. Its Easter pageant Jesus the Christ has been identified as the "largest annual outdoor Easter pageant in the world". The church encourages entertainment without violence, sexual content, or vulgar language; many church members specifically avoid rated-R movies.

The church's official choir, the Tabernacle Choir at Temple Square, was formed in the mid-19th century and performs in the Salt Lake Tabernacle. They have traveled to more than 28 countries, and are considered one of the most famous choirs in the world. The choir has received a Grammy Award, four Emmy Awards, two Peabody Awards, and the National Medal of Arts.

Political involvement in the U.S.
The LDS Church states it generally takes no partisan role in politics, but encourages its members to play an active role as responsible citizens in their communities, including becoming informed about issues and voting. The church maintains that the faith's values can be found among many political parties. It also generally does not take sides in global conflicts.

A 2012 Pew Center on Religion and Public Life survey indicates that 74 percent of U.S. members lean towards the Republican Party. Some liberal members say they feel that they have to defend their worthiness due to political differences. Democrats and those who lean Democrat made up 18% of church members surveyed in the 2014 Pew Research Center's Religious Landscape Survey.

The official church stance on staying out of politics does not include if there are instances of what church leaders deem to be moral issues, or issues the church believes "directly affect [its] mission, teachings or operations." It has previously opposed same-sex marriage in California Prop 8, supported a gay rights bill in Salt Lake City which bans discrimination against homosexual persons in housing and employment, opposed gambling, opposed storage of nuclear waste in Utah, and supported an approach to U.S. immigration policy as outlined in the Utah Compact. It also opposed a ballot initiative legalizing medicinal marijuana in Utah, but supported a possible alternative to it. In 2019 and 2021, the church stated its opposition to the Equality Act, which would prohibit discrimination in the United States on the basis of sexual orientation and gender identity, but supports alternate legislation that it says would protect both LGBTQ rights and religious freedom. In 2022, the church stated its support for the Respect for Marriage Act—which codified same-sex marriage as legal in the United States—due to the "protections for religious freedom" it includes.

In the 117th United States Congress, there are nine LDS Church members, including all six members of Utah's congressional delegation, all of whom are Republicans. Utah's current governor, Spencer Cox, is also a church member, as are supermajorities in both houses of the Utah State Legislature. Church member and current U.S. Senator Mitt Romney was the Republican Party's nominee in the U.S. 2012 presidential election.

Demographics
The church reports a worldwide membership of 17 million. The church's definition of "membership" includes all persons who were ever baptized, or whose parents were members while the person was under the age of eight (called "members of record"), who have neither been excommunicated nor asked to have their names removed from church records. As of September 2019, approximately 9.6 million members reside outside the United States.

According to its statistics, the church is the fourth largest religious body in the United States. Although the church does not publish attendance figures, researchers estimate that attendance at weekly LDS worship services globally is around 4 million. Members living in the U.S. and Canada constitute 46 percent of membership, Latin America 38 percent, and members in the rest of the world 16 percent. The 2012 Pew Forum on Religion & Public Life survey, conducted by Princeton Survey Research Associates International, found that approximately 2 percent of the U.S. adult population self-identified as Mormon.

Membership is concentrated geographically in the Intermountain West, in a specific region sometimes known as the Mormon corridor. Church members and some others from the United States colonized this region in the mid-to-late 1800s, dispossessing several indigenous tribes in the process.

The church experienced rapid numerical growth in the 20th century, especially in the 1980s and 1990s. In the 21st century, however, church membership growth has slowed. In 2022, eight of the top ten nations with the highest LDS membership growth rate were in Africa, and Latino people are one of the fastest growing ethnic groups with millions of LDS adherents in Latin American countries.

In the United States, church members tend to be more highly educated than the general population. The racial and ethnic composition of membership in the United States is one of the least diverse in the country. Church membership is predominantly white; the membership of blacks is significantly lower than the general U.S. population.

The LDS Church does not release official statistics on church activity, but it is likely that only approximately 40 percent of its recorded membership in the United States and 30 percent worldwide regularly attend weekly Sunday worship services. A 2016 survey found a majority (54%) of millennials raised in the church had disaffiliated. Activity rates vary with age, and disengagement occurs most frequently between age 16 and 25. Young single adults are more likely to become inactive than their married counterparts, and women tend to be more active than men.

Humanitarian services

The LDS Church is widely known for providing worldwide humanitarian service. The church's welfare and humanitarian efforts are coordinated by Philanthropies, a church department under the direction of the Presiding Bishopric. Welfare efforts, originally initiated during the Great Depression, provide aid for the poor, financed by donations from church members. Donations are also used to operate bishop's storehouses, which package and store food for lower-income people at low cost. In 2016, the church reported that it had spent a total of $1.2 billion on humanitarian aid over the previous 30 years.

Church humanitarian aid includes organizing food security, clean water, mobility, and healthcare initiatives, operating thrift stores, maintaining a service project website, and directly funding or partnering with other organizations. The church reports that the value of all charitable donations in 2021 was $906 million. Independent reporting has found that the Church's charity organization, LDS Charities, gave a total of $177 million from 2008 to 2020.

The church also distributes money and aid to disaster victims worldwide. In 2017, the church partnered with Catholic Relief Services and other organizations to provide aid to several African and Middle Eastern nations. In 2010, it partnered with Islamic Relief to help victims of flooding in Pakistan. Latter-day Saint Charities (a branch of the church's welfare department) increased food production during the COVID-19 pandemic and donated healthcare supplies to 16 countries affected by the crisis. The church has donated $4 million to aid refugees fleeing from the 2022 Russian invasion of Ukraine. In 2022, the church gave $32 million to the United Nations World Food Programme, in its largest one-time donation to a humanitarian organization to that point.

Criticism and controversies
The church has been subject to criticism and the subject of controversy since its early years in New York and Pennsylvania.

Modern criticism of the church includes disputed claims, allegations of historical revisionism by the church, child sexual abuse, sexism, racism,  and anti-LGBTQ+ teachings. Notable 20th-century critics include Jerald and Sandra Tanner and historian Fawn Brodie.

Child sexual abuse
The church has been criticized for a number of abuses allegedly perpetrated or covered up by local church leadership; several cases have been settled out of court. In other cases, church leaders have been criticized for: allegedly failing to report abuse to law enforcement; improperly invoking clergy-penitent privilege in so doing; and failing to keep records of sexual abuse claims which were reported through its Helpline phone number.

Scriptures
In the late 1820s, criticism centered on the claim by Joseph Smith to have been led to a set of gold plates from which the Book of Mormon was reputedly translated.

Mainstream archaeological, historical, and scientific communities have discovered little to support the existence of the civilizations described in the Book of Mormon, and do not consider it to be an actual record of historical events. Scholars have pointed out a number of anachronisms within the text. They argue that no evidence of a reformed Egyptian language has ever been discovered; the Book of Mormon explicitly says it was written in Reformed Egyptian, and so the non-existence of this language would challenge the book's claims about its own origin. Also, general archaeological and genetic evidence has not supported the book's statements about any known indigenous peoples of the Americas.

Since its publication in 1842, the Book of Abraham (currently published as part of the canonical Pearl of Great Price) has also been a major source of controversy. Numerous non-Mormon Egyptologists, beginning in the late 19th century, have disagreed with Joseph Smith's explanations of the book's facsimiles. Translations of the original papyri—by both Mormon and non-Mormon Egyptologists—do not match the text of the Book of Abraham as purportedly translated by Joseph Smith. Indeed, the transliterated text from the recovered papyri and facsimiles published in the Book of Abraham contain no direct references to Abraham. Scholars have also asserted that damaged portions of the papyri were reconstructed incorrectly by Smith or his associates.

Polygamy
Polygamy (called plural marriage within the church) was practiced by church leaders for more than half of the 19th century, and practiced publicly from 1852 to 1890 by between 20 and 30 percent of Latter-day Saint families. It was instituted privately in the 1830s by founder Joseph Smith and announced publicly in 1852 at the direction of Brigham Young.

For over 60 years, the church and the United States were at odds over the issue: at one point, the Republican platform referenced "the twin relics of barbarism—polygamy and slavery." The church defended the practice as a matter of religious freedom, while the federal government aggressively sought to eradicate it; in 1862, the United States Congress passed the Morrill Anti-Bigamy Act, which prohibited plural marriage in the territories.

In 1890, church president Wilford Woodruff issued a Manifesto that officially terminated the practice in the United States, though it did not dissolve existing polygamous marriages of any couples, some of which continued to cohabit into the 1950s. Some church members continued to enter into polygamous marriages in Canada and Mexico, but these eventually stopped in 1904 when church president Joseph F. Smith disavowed polygamy before Congress and issued a "Second Manifesto," calling for all plural marriages in the church to cease. Several small fundamentalist groups, seeking to continue the practice, split from the LDS Church, but the mainline church now excommunicates members found practicing polygamy and distances itself from those fundamentalist groups. The church does allow divorced or widowed men to be sealed to other women without cancelling any existing sealings.

Black people

The teachings, attitudes, and practices of top LDS Church leaders towards Black people have changed significantly from its founding years to the modern times, and the church has faced criticism and controversy on these topics. Joseph Smith allowed several black men to be ordained as priests during his presidency, but also taught that the dark skin of people of Black African ancestry was a sign of a curse from God. Both Smith and Brigham Young taught that Black people were subject to the Biblical curse of Ham, and curse of Cain. Both made statements in support of Black enslavement, and Young legalized Black slavery while acting as Utah territory's governor.

From 1844 to 1978, the church barred Black women and men from participating in temple ordinances necessary for the highest level of salvation; prevented most men of Black African descent from being ordained to the church's lay, all-male priesthood;  supported racial segregation in its communities and schools;  taught that righteous Black people would be made White after death;   and opposed interracial marriage. Leaders taught on many occasions during this time that Black people were less righteous in the pre-existence. The temple and priesthood racial restrictions were lifted by top leaders in 1978 following public pressure during the United States' civil rights movement. In 2013 the church directly disavowed its previous teachings on race for the first time. In 2018, the Church formed an alliance with the NAACP in an effort to improve race relations.

Native American people
Over the past two centuries, the relationship between Native American people and the LDS Church has included friendly ties, displacement, battles, slavery, education placement programs, official and unofficial discrimination, and criticism. Church leadership and publications taught that Native Americans are descendants of Lamanites, a dark-skinned and cursed people from the Book of Mormon. More recently, LDS researchers and publications generally favor a smaller geographic footprint of Lamanite descendants. There is no direct support amongst mainstream historians and archaeologists for the historicity of the Book of Mormon or Middle Eastern origins for any Native American peoples.

Soon after Mormons colonized the Salt Lake Valley in 1847, Native American child slaves became a vital source of labor. The settlers initially had some peaceful relations, but because resources were scarce in the desert, hostilities broke out with the local Native Americans. According to LDS Church Historian Marlin K. Jensen as more LDS immigrants arrived and took over the land of Native nations, "Resources the Indians had relied on for generations diminished, and in time they felt forced to resist and fight for their own survival ... the land and cultural birthright Indians once possessed in the Great Basin were largely taken from them." Within 50 years of Mormon settlement, the population of Utah's Native Americans was reduced by almost 90%.

The church ran an Indian Placement Program between the 1950s and the 1990s, wherein indigenous children were adopted by white church members. Criticism resulted during and after the program, including claims of improper assimilation and even abuse. However, many of the involved students and families praised the program. Church leaders taught for decades that Native Americans' darker skin would be made lighter due to their righteousness.

LGBTQ+ individuals

The church's policies and treatment of sexual minorities and gender minorities have long been the subject of external criticism, as well as internal controversy and disaffection by members. Because of its ban against same-sex sexual activity and same-sex marriage, the LDS church taught for decades that any adherents attracted to the same sex could and should change that through sexual orientation change efforts and righteous striving. The church provided therapy and programs for attempting to change sexual orientation.

Current teachings and policies leave homosexual members with the options of: attempts to change their sexual orientation, entering a mixed-orientation opposite-sex marriage, or lifelong celibacy. Some have argued that church teachings against homosexuality and the treatment of LGBT members by other adherents and leaders have contributed to their elevated rates of PTSD and depression,  as well as suicide and teen homelessness. The church's decades-long, political involvement opposing US same-sex marriage laws has further garnered criticism and protests.

Baptismal candidates considering gender-affirming surgery are not allowed to be baptized, and those who have already had one need special clearance from the First Presidency through the local full-time mission president before baptism. Undergoing a "trans-sexual [sic] operation," including gender-affirming surgery like chest surgery (i.e. top surgery) may imperil the membership of a current church member. Ordinances after baptism such as receiving the priesthood and temple endowments are only done according to birth sex. Members that gender express through clothing or a pronoun change differing from the sex assigned at their birth will receive membership restrictions and a notation on their membership records.

Criticism of Joseph Smith
In the 1830s, the church was heavily criticized for Smith's handling of a banking failure in Kirtland, Ohio. After the Mormons migrated west, there was fear and suspicion about the LDS Church's political and military power in Missouri, culminating in the 1838 Mormon War and the Mormon Extermination Order (Missouri Executive Order 44) by Governor Lilburn Boggs. In the 1840s, criticism of the church included its theocratic aspirations in Nauvoo, Illinois. Criticism of the practice of plural marriage and other doctrines Smith taught were published in the Nauvoo Expositor in 1844. After Smith took a leading role in having the paper's printing press destroyed, he was charged with treason and jailed. While he awaited trial, an angry mob stormed the jailhouse and shot him fatally.

In modern popular opinion, non-Mormons in the U.S. generally consider Smith a "charlatan, scoundrel, and heretic." The Book of Mormon musical relentlessly mocks his account of the golden plates. In 2007, Christopher Hitchens, writing in Slate magazine, lambasted Smith as a mountebank, charlatan, and fraud (and the church itself as a "ridiculous cult" and a "racket" that became a religion).

Financial controversy
The church's failure to make its finances public has drawn criticism from commentators who consider its practices too secretive. The church has fought to keep its internal financial information out of the public record.

In December 2019, a whistleblower alleged the church held over $100 billion in investment funds through its investment management company, Ensign Peak Advisors (EP); that it failed to use the funds for charitable purposes and instead used them in for-profit ventures; and that it misled contributors and the public about the usage and extent of those funds. In response, the church's First Presidency stated that "the Church complies with all applicable law governing our donations, investments, taxes, and reserves," and that "a portion" of funds received by the church are "methodically safeguarded through wise financial management and the building of a prudent reserve for the future". The church has not directly addressed the fund's size to the public, but third parties have treated the disclosures as legitimate. The disclosure of Ensign Peak has led to criticism that the church's wealth may be excessive.

The church has transferred more than 1 billion dollars of tithing collected in Canada, tax-free, to church universities over a 15-year period. In October 2022, The Sydney Morning Herald announced that while the church publicly claimed to have donated US$1.35 billion to charity between 2008 and 2020, its private financial reports showed that it donated only US$0.177 billion.

In February 2023, the U.S. Securities and Exchange Commission (SEC) issued a $5 million penalty to the church and its investment company, EP. The SEC alleged that the church concealed its investments and their management in multiple shell companies from 1997 to 2019; the SEC believes these shell companies were approved by senior church leadership to avoid public transparency. The church released a statement that in 2000 EP "received and relied upon legal counsel regarding how to comply with its reporting obligations while attempting to maintain the privacy of the portfolio." After initial SEC concern in June 2019, the church stated that EP "adjusted its approach and began filing a single aggregated report."

Official church websites

 * ChurchofJesusChrist.org – main site
 * ComeUntoChrist.org – ComeUntoChrist.org, contains information about basic beliefs (formerly Mormon.org)


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Chemical thermodynamics

Chemical thermodynamics is the study of the interrelation of heat and work with chemical reactions or with physical changes of state within the confines of the laws of thermodynamics. Chemical thermodynamics involves not only laboratory measurements of various thermodynamic properties, but also the application of mathematical methods to the study of chemical questions and the spontaneity of processes.

The structure of chemical thermodynamics is based on the first two laws of thermodynamics. Starting from the first and second laws of thermodynamics, four equations called the "fundamental equations of Gibbs" can be derived. From these four, a multitude of equations, relating the thermodynamic properties of the thermodynamic system can be derived using relatively simple mathematics. This outlines the mathematical framework of chemical thermodynamics.

History
In 1865, the German physicist Rudolf Clausius, in his Mechanical Theory of Heat, suggested that the principles of thermochemistry, e.g. the heat evolved in combustion reactions, could be applied to the principles of thermodynamics. Building on the work of Clausius, between the years 1873-76 the American mathematical physicist Willard Gibbs published a series of three papers, the most famous one being the paper On the Equilibrium of Heterogeneous Substances. In these papers, Gibbs showed how the first two laws of thermodynamics could be measured graphically and mathematically to determine both the thermodynamic equilibrium of chemical reactions as well as their tendencies to occur or proceed. Gibbs’ collection of papers provided the first unified body of thermodynamic theorems from the principles developed by others, such as Clausius and Sadi Carnot.

During the early 20th century, two major publications successfully applied the principles developed by Gibbs to chemical processes and thus established the foundation of the science of chemical thermodynamics. The first was the 1923 textbook Thermodynamics and the Free Energy of Chemical Substances by Gilbert N. Lewis and Merle Randall. This book was responsible for supplanting the chemical affinity with the term free energy in the English-speaking world. The second was the 1933 book Modern Thermodynamics by the methods of Willard Gibbs written by E. A. Guggenheim. In this manner, Lewis, Randall, and Guggenheim are considered as the founders of modern chemical thermodynamics because of the major contribution of these two books in unifying the application of thermodynamics to chemistry.

Overview
The primary objective of chemical thermodynamics is the establishment of a criterion for determination of the feasibility or spontaneity of a given transformation. In this manner, chemical thermodynamics is typically used to predict the energy exchanges that occur in the following processes:
 * 1) Chemical reactions
 * 2) Phase changes
 * 3) The formation of solutions

The following state functions are of primary concern in chemical thermodynamics:

 * Internal energy (U)
 * Enthalpy (H)
 * Entropy (S)
 * Gibbs free energy (G)

Most identities in chemical thermodynamics arise from application of the first and second laws of thermodynamics, particularly the law of conservation of energy, to these state functions.

The three laws of thermodynamics (global, unspecific forms):

1. The energy of the universe is constant.

2. In any spontaneous process, there is always an increase in entropy of the universe.

3. The entropy of a perfect crystal (well ordered) at 0 Kelvin is zero.

Chemical energy
Chemical energy is the energy that can be released when chemical substances undergo a transformation through a chemical reaction. Breaking and making chemical bonds involves energy release or uptake, often as heat that may be either absorbed by or evolved from the chemical system.

Energy released (or absorbed) because of a reaction between chemical substances ("reactants") is equal to the difference between the energy content of the products and the reactants. This change in energy is called the change in internal energy of a chemical system. It can be calculated from $$\Delta_{\rm f}U^{\rm o}_{\mathrm {reactants}}$$, the internal energy of formation of the reactant molecules related to the bond energies of the molecules under consideration, and $$\Delta_{\rm f}U^{\rm o}_{\mathrm {products}}$$, the internal energy of formation of the product molecules. The change in internal energy is equal to the heat change if it is measured under conditions of constant volume (at STP condition), as in a closed rigid container such as a bomb calorimeter. However, at constant pressure, as in reactions in vessels open to the atmosphere, the measured heat is usually not equal to the internal energy change, because pressure-volume work also releases or absorbs energy. (The heat change at constant pressure is called the enthalpy change; in this case the widely tabulated enthalpies of formation are used.)

A related term is the heat of combustion, which is the chemical energy released due to a combustion reaction and of interest in the study of fuels. Food is similar to hydrocarbon and carbohydrate fuels, and when it is oxidized, its energy release is similar (though assessed differently than for a hydrocarbon fuel — see food energy).

In chemical thermodynamics, the term used for the chemical potential energy is chemical potential, and sometimes the Gibbs-Duhem equation is used.

Chemical reactions
In most cases of interest in chemical thermodynamics there are internal degrees of freedom and processes, such as chemical reactions and phase transitions, which create entropy in the universe unless they are at equilibrium or are maintained at a "running equilibrium" through "quasi-static" changes by being coupled to constraining devices, such as pistons or electrodes, to deliver and receive external work. Even for homogeneous "bulk" systems, the free-energy functions depend on the composition, as do all the extensive thermodynamic potentials, including the internal energy. If the quantities { Ni }, the number of chemical species, are omitted from the formulae, it is impossible to describe compositional changes.

Gibbs function or Gibbs Energy
For an unstructured, homogeneous "bulk" system, there are still various extensive compositional variables { Ni } that G depends on, which specify the composition (the amounts of each chemical substance, expressed as the numbers of molecules present or the numbers of moles). Explicitly,

 * $$ G = G(T,P,\{N_i\})\,.$$

For the case where only PV work is possible,

 * $$ \mathrm{d}G = -S\, \mathrm{d}T + V \, \mathrm{d}P + \sum_i \mu_i \, \mathrm{d}N_i \,$$

a restatement of the fundamental thermodynamic relation, in which μi is the chemical potential for the i-th component in the system

 * $$ \mu_i = \left( \frac{\partial G}{\partial N_i}\right)_{T,P,N_{j\ne i},etc. } \,.$$

The expression for dG is especially useful at constant T and P, conditions, which are easy to achieve experimentally and which approximate the conditions in living creatures

 * $$ (\mathrm{d}G)_{T,P} = \sum_i \mu_i \, \mathrm{d}N_i\,.$$

Chemical affinity
While this formulation is mathematically defensible, it is not particularly transparent since one does not simply add or remove molecules from a system. There is always a process involved in changing the composition; e.g., a chemical reaction (or many), or movement of molecules from one phase (liquid) to another (gas or solid). We should find a notation which does not seem to imply that the amounts of the components ( Ni ) can be changed independently. All real processes obey conservation of mass, and in addition, conservation of the numbers of atoms of each kind.

Consequently, we introduce an explicit variable to represent the degree of advancement of a process, a progress variable ξ for the extent of reaction (Prigogine & Defay, p. 18; Prigogine, pp. 4–7; Guggenheim, p. 37.62), and to the use of the partial derivative ∂G/∂ξ (in place of the widely used "ΔG", since the quantity at issue is not a finite change). The result is an understandable expression for the dependence of dG on chemical reactions (or other processes). If there is just one reaction
 * $$(\mathrm{d}G)_{T,P} = \left( \frac{\partial G}{\partial \xi}\right)_{T,P} \, \mathrm{d}\xi.\,$$

If we introduce the stoichiometric coefficient for the i-th component in the reaction

 * $$\nu_i = \partial N_i / \partial \xi \,$$

(negative for reactants), which tells how many molecules of i are produced or consumed, we obtain an algebraic expression for the partial derivative

 * $$ \left( \frac{\partial G}{\partial \xi} \right)_{T,P} = \sum_i \mu_i \nu_i = -\mathbb{A}\,$$

where we introduce a concise and historical name for this quantity, the "affinity", symbolized by A, as introduced by Théophile de Donder in 1923.(De Donder; Progogine & Defay, p. 69; Guggenheim, pp. 37, 240) The minus sign ensures that in a spontaneous change, when the change in the Gibbs free energy of the process is negative, the chemical species have a positive affinity for each other. The differential of G takes on a simple form that displays its dependence on composition change

 * $$(\mathrm{d}G)_{T,P} = -\mathbb{A}\, d\xi \,.$$

If there are a number of chemical reactions going on simultaneously, as is usually the case,

 * $$(\mathrm{d}G)_{T,P} = -\sum_k\mathbb{A}_k\, d\xi_k \,.$$

with a set of reaction coordinates { ξj }, avoiding the notion that the amounts of the components ( Ni ) can be changed independently. The expressions above are equal to zero at thermodynamic equilibrium, while they are negative when chemical reactions proceed at a finite rate, producing entropy. This can be made even more explicit by introducing the reaction rates dξj/dt. For every physically independent process (Prigogine & Defay, p. 38; Prigogine, p. 24)

 * $$ \mathbb{A}\ \dot{\xi} \le 0 \,.$$

This is a remarkable result since the chemical potentials are intensive system variables, depending only on the local molecular milieu. They cannot "know" whether temperature and pressure (or any other system variables) are going to be held constant over time. It is a purely local criterion and must hold regardless of any such constraints. Of course, it could have been obtained by taking partial derivatives of any of the other fundamental state functions, but nonetheless is a general criterion for (−T times) the entropy production from that spontaneous process; or at least any part of it that is not captured as external work. (See Constraints below.)

We now relax the requirement of a homogeneous "bulk" system by letting the chemical potentials and the affinity apply to any locality in which a chemical reaction (or any other process) is occurring. By accounting for the entropy production due to irreversible processes, the equality for dG is now replaced by

 * $$ \mathrm{d}G = - S \, \mathrm{d}T + V \, \mathrm{d}P -\sum_k\mathbb{A}_k\, \mathrm{d}\xi_k + \mathrm{\delta} W'\,$$

or

 * $$ \mathrm{d}G_{T,P} = -\sum_k\mathbb{A}_k\, \mathrm{d}\xi_k + \mathrm{\delta} W'.\,$$

Any decrease in the Gibbs function of a system is the upper limit for any isothermal, isobaric work that can be captured in the surroundings, or it may simply be dissipated, appearing as T times a corresponding increase in the entropy of the system and its surrounding. Or it may go partly toward doing external work and partly toward creating entropy. The important point is that the extent of reaction for a chemical reaction may be coupled to the displacement of some external mechanical or electrical quantity in such a way that one can advance only if the other also does. The coupling may occasionally be rigid, but it is often flexible and variable.

Solutions
In solution chemistry and biochemistry, the Gibbs free energy decrease (∂G/∂ξ, in molar units, denoted cryptically by ΔG) is commonly used as a surrogate for (−T times) the global entropy produced by spontaneous chemical reactions in situations where no work is being done; or at least no "useful" work; i.e., other than perhaps ± P dV. The assertion that all spontaneous reactions have a negative ΔG is merely a restatement of the second law of thermodynamics, giving it the physical dimensions of energy and somewhat obscuring its significance in terms of entropy. When no useful work is being done, it would be less misleading to use the Legendre transforms of the entropy appropriate for constant T, or for constant T and P, the Massieu functions −F/T and −G/T, respectively.

Non-equilibrium
Generally the systems treated with the conventional chemical thermodynamics are either at equilibrium or near equilibrium. Ilya Prigogine developed the thermodynamic treatment of open systems that are far from equilibrium. In doing so he has discovered phenomena and structures of completely new and completely unexpected types. His generalized, nonlinear and irreversible thermodynamics has found surprising applications in a wide variety of fields.

The non-equilibrium thermodynamics has been applied for explaining how ordered structures e.g. the biological systems, can develop from disorder. Even if Onsager's relations are utilized, the classical principles of equilibrium in thermodynamics still show that linear systems close to equilibrium always develop into states of disorder which are stable to perturbations and cannot explain the occurrence of ordered structures.

Prigogine called these systems dissipative systems, because they are formed and maintained by the dissipative processes which take place because of the exchange of energy between the system and its environment and because they disappear if that exchange ceases. They may be said to live in symbiosis with their environment.

The method which Prigogine used to study the stability of the dissipative structures to perturbations is of very great general interest. It makes it possible to study the most varied problems, such as city traffic problems, the stability of insect communities, the development of ordered biological structures and the growth of cancer cells to mention but a few examples.

System constraints
In this regard, it is crucial to understand the role of walls and other constraints, and the distinction between independent processes and coupling. Contrary to the clear implications of many reference sources, the previous analysis is not restricted to homogeneous, isotropic bulk systems which can deliver only PdV work to the outside world, but applies even to the most structured systems. There are complex systems with many chemical "reactions" going on at the same time, some of which are really only parts of the same, overall process. An independent process is one that could proceed even if all others were unaccountably stopped in their tracks. Understanding this is perhaps a "thought experiment" in chemical kinetics, but actual examples exist.

A gas-phase reaction at constant temperature and pressure which results in an increase in the number of molecules will lead to an increase in volume. Inside a cylinder closed with a piston, it can proceed only by doing work on the piston. The extent variable for the reaction can increase only if the piston moves out, and conversely if the piston is pushed inward, the reaction is driven backwards.

Similarly, a redox reaction might occur in an electrochemical cell with the passage of current through a wire connecting the electrodes. The half-cell reactions at the electrodes are constrained if no current is allowed to flow. The current might be dissipated as Joule heating, or it might in turn run an electrical device like a motor doing mechanical work. An automobile lead-acid battery can be recharged, driving the chemical reaction backwards. In this case as well, the reaction is not an independent process. Some, perhaps most, of the Gibbs free energy of reaction may be delivered as external work.

The hydrolysis of ATP to ADP and phosphate can drive the force-times-distance work delivered by living muscles, and synthesis of ATP is in turn driven by a redox chain in mitochondria and chloroplasts, which involves the transport of ions across the membranes of these cellular organelles. The coupling of processes here, and in the previous examples, is often not complete. Gas can leak slowly past a piston, just as it can slowly leak out of a rubber balloon. Some reaction may occur in a battery even if no external current is flowing. There is usually a coupling coefficient, which may depend on relative rates, which determines what percentage of the driving free energy is turned into external work, or captured as "chemical work", a misnomer for the free energy of another chemical process.

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title: Chemical thermodynamics