Primogeniture is the right, by law or custom, of the firstborn legitimate son to inherit his parent's entire or main estate in preference to shared inheritance among all or some children, any illegitimate child or any collateral relative. In some contexts it instead means the inheritance of the firstborn daughter; the first definition given is known as male-line primogeniture, the classical form popular in European jurisdictions among others until into the 20th century. In the absence of male-line offspring, variations were expounded to entitle a daughter or a brother or, in the absence of either, to another collateral relative, in a specified order. Variations have tempered the traditional, sole-beneficiary, right or, in the West since World War II, eliminate the preference for males over females. Most monarchies in Western Europe have eliminated this, in succession: Belgium, Luxembourg, Norway and the United Kingdom. English primogeniture endures in titles of nobility: any first-placed direct male-line descendant inherits the title before siblings and similar, this being termed "by right of substitution" for the deceased heir.

The effect of English primogeniture was to keep estates undivided wherever possible and to disinherit real property from female relations unless only daughters survived in which case the estate thus results in division. The principle has applied in history to inheritance of land as well as inherited titles and offices, most notably monarchies, continuing until modified or abolished. Other forms of inheritance in monarchies continue; the Holy Roman Emperor was selected for enthronement by a small number of powerful prince electors from among Europe's Christian males of inherited nobility. Succession to the Saudi Arabian throne uses a form of lateral agnatic seniority, as did the Kievan Rus', the early Kingdom of Scotland, the Mongol Empire or the Ottoman Empire. Research shows that authoritarian regimes that rely on primogeniture for succession were more stable than forms of authoritarian rule with alternative succession arrangements. Absolute, equal, or lineal primogeniture is a form of primogeniture in which gender is irrelevant for inheritance.

No modern monarchy before 1980 implemented this. The Basques of the Kingdom of Navarre transmitted title and property to the firstborn regardless of sex; the Navarrese monarchy, was inherited by dynasties from outside of Navarre, which followed different successional laws male preference primogeniture. Only the Basque lower nobility and free families of the Basque country and other regions continued to follow this custom, which persisted as late as the 19th century. An ancient and alternative way in which women succeeded to power without displacing the direct male line descendants of the first monarchs, was consortium or coregency between husband and wife or other relatives; the most notable are the Egyptian cases of Hatshepsut and Thutmose III, the monarchs of the Ptolemaic Dynasty. In 1980, Sweden amended its constitution to adopt royal succession by absolute primogeniture, displacing King Carl XVI Gustaf's infant son, Prince Carl Philip, in favor of his elder daughter, Princess Victoria, in the process.

Several monarchies have since followed suit: the Netherlands in 1983, Norway in 1990, Belgium in 1991, Denmark in 2009, Luxembourg in 2011, the Commonwealth realms in 2015. Monaco, the Netherlands, Norway deviated from traditional primogeniture in the late 20th or early 21st century by restricting succession to the crown to relatives within a specified degree of kinship to the most recent monarch. Other monarchies have changed or considered changing to absolute primogeniture: With the birth of Infanta Leonor of Spain on 31 October 2005 to the heir apparent Felipe, Prince of Asturias, Princess Letizia, the Spanish Prime Minister José Luis Rodríguez Zapatero reaffirmed the intention of the government to institute, by amendment of the Spanish constitution, absolute primogeniture. Zapatero's proposal was supported by the leader of the main opposition party, the conservative Partido Popular, making its passage probable. However, Zapatero's administration ended before an amendment was drafted, the succeeding government has not pursued it.

The Prince counseled reformers that there was plenty of time before any constitutional amendment would need to be enacted because the expectation was to leave him next in line to succeed his father despite his elder sisters' continued status as dynasts. Felipe succeeded to the throne as Felipe VI upon his father's abdication in 2014, by which time he had two daughters. Felipe VI has no son that would, absent the constitutional amendment, displace Leonor as heir apparent. In July 2006, the Nepalese government proposed adopting absolute primogeniture, but the monarc

The enthalpy of vaporization known as the heat of vaporization or heat of evaporation, is the amount of energy that must be added to a liquid substance, to transform a quantity of that substance into a gas. The enthalpy of vaporization is a function of the pressure; the enthalpy of vaporization is quoted for the normal boiling temperature of the substance. The heat of vaporization is temperature-dependent, though a constant heat of vaporization can be assumed for small temperature ranges and for reduced temperature T r ≪ 1; the heat of vaporization diminishes with increasing temperature and it vanishes at a certain point called the critical temperature. Above the critical temperature, the liquid and vapor phases are indistinguishable, the substance is called a supercritical fluid. Values are quoted in J/mol or kJ/mol, although kJ/kg or J/g, older units like kcal/mol, cal/g and Btu/lb are sometimes still used, among others; the enthalpy of condensation is by definition equal to the enthalpy of vaporization with the opposite sign: enthalpy changes of vaporization are always positive, whereas enthalpy changes of condensation are always negative.

The enthalpy of vaporization can be written as Δ H v a p = Δ U v a p + p Δ V It is equal to the increased internal energy of the vapor phase compared with the liquid phase, plus the work done against ambient pressure. The increase in the internal energy can be viewed as the energy required to overcome the intermolecular interactions in the liquid. Hence helium has a low enthalpy of vaporization, 0.0845 kJ/mol, as the van der Waals forces between helium atoms are weak. On the other hand, the molecules in liquid water are held together by strong hydrogen bonds, its enthalpy of vaporization, 40.65 kJ/mol, is more than five times the energy required to heat the same quantity of water from 0 °C to 100 °C. Care must be taken, when using enthalpies of vaporization to measure the strength of intermolecular forces, as these forces may persist to an extent in the gas phase, so the calculated value of the bond strength will be too low; this is true of metals, which form covalently bonded molecules in the gas phase: in these cases, the enthalpy of atomization must be used to obtain a true value of the bond energy.

An alternative description is to view the enthalpy of condensation as the heat which must be released to the surroundings to compensate for the drop in entropy when a gas condenses to a liquid. As the liquid and gas are in equilibrium at the boiling point, ΔvG = 0, which leads to: Δ v S = S g a s − S l i q u i d = Δ v H / T b As neither entropy nor enthalpy vary with temperature, it is normal to use the tabulated standard values without any correction for the difference in temperature from 298 K. A correction must be made if the pressure is different from 100 kPa, as the entropy of a gas is proportional to its pressure: the entropies of liquids vary little with pressure, as the compressibility of a liquid is small; these two definitions are equivalent: the boiling point is the temperature at which the increased entropy of the gas phase overcomes the intermolecular forces. As a given quantity of matter always has a higher entropy in the gas phase than in a condensed phase, from Δ G = Δ H − T Δ S,the Gibbs free energy change falls with increasing temperature: gases are favored at higher temperatures, as is observed in practice.

Estimation of the enthalpy of vaporization of electrolyte solutions can be carried out using equations based on the chemical thermodynamic models, such as Pitzer model or TCPC model. The vaporization of metals is a key step in metal vapor synthesis, which exploits the increased reactivity of metal atoms or small particles relative to the bulk elements. Enthalpies of vaporization of common substances, measured at their respective standard boiling points: Enthalpy of fusion Enthalpy of sublimation Joback method Clausius-Clapeyron equation CODATA Key Values for Thermodynamics Gmelin, Leopold. Gmelin-Handbuch der anorganischen Chemie / 08 a. Berlin: Springer. Pp. 116–117. ISBN 978-3-540-93516-2. NIST Chemistry WebBook Young, Francis W. Sears, Mark W. Zemansky, Hugh D.. Univer

Aaron Albert Mossell II was the first African-American to graduate from the University of Pennsylvania Law School. Aaron Albert Mossell II was born in Ontario in 1863, the youngest of six children, his parents had moved with their first three children from Maryland to Hamilton in the 1850s to escape the racial discrimination in the United States. His father Aaron Albert Mossell I, the grandson of slaves, became a brickmaker and in Hamilton went to school to learn to read and write, his mother Eliza Bowers was a free woman from Baltimore whose family had been deported to Trinidad when she was a child. She returned and met Mossell. By 1870 the family had lived in Lockport, New York. Aaron Mossell II graduated from Lincoln University, he earned his law degree at the University of Pennsylvania Law School in 1888 as the first African American to graduate. Mossell practiced law with two African-American partners in offices in the Witherspoon Building, he was solicitor of the Frederick Douglass Memorial Hospital, where his brother Nathan was medical director.

He was said to have defended some African-American men after the racial riots of 1917-1919 in Philadelphia. He died on February 1951 in Cardiff, Wales. Mossell married Mary Louisa Tanner in Philadelphia around 1890, they had three children. Aaron Albert Tanner III became a pharmacist in Philadelphia. Elizabeth Mossell Anderson became Dean of Women at Virginia State College and at Wilberforce University in Ohio. Sadie Tanner Mossell graduated from Penn and served as an editor of the Law Review. Became a practicing lawyer, Assistant City Solicitor and activist on civil rights issues Mossell separated from his wife and family when Sadie was about a year old, the couple divorced, he moved to Cardiff, where he was living by the 1930s and remained the rest of his life