Physical chemistry. Study the physical foundation of the laws of chemistry .
Its main fields are chemical thermodynamics – which studies energy – direction and balance of chemical transformations – and chemical kinetics – which studies the speed with which reactions occur.
Physicochemistry represents a branch where a change occurs in various sciences, such as chemistry, physics , thermodynamics , electrochemistry, and quantum mechanics where mathematical functions can represent interpretations at the molecular and structural atomic level. Changes in temperature, pressure, volume, heat and work in the systems, solid, liquid and / or gas are also related to these interpretations of molecular interactions.
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- 1 History
- 2 Early discoveries
- 3 Featured Physicochemicals
- 4 References
- 5 Sources
Physicochemistry was not established as an independent specialty of chemistry until the beginning of the 20th century . The creation dates of two of the first magazines that incorporated this name into their title can be taken as the starting point of the new specialty: the German Zeitschrift für physicalische Chemie directed by Wolfgang Ostwald (1853-1932) and Jacobus Henricus Van’t Hoff ( 1852 – 1911 ), which began publication in 1887 , and the American Journal of Physical Chemistry edited by Wilder Dwight Bancroft ( 1867 – 1953 ) from 1896 . Despite this, throughout the 19th centuryRemarkable contributions were made to some of the fields that usually come together under physicochemistry, such as electrochemistry , thermochemistry, or chemical kinetics .
The work of Alessandro Volta ( 1745 – 1827 ), especially the battery that bears his name, was the starting point of many works in which the effects of electricity on chemical compounds were studied . In the early 1800s, Humphry Davy ( 1778 – 1829 ) passed the electric current through soda and molten potash, allowing him to study two new metals : sodium and potassium . His main disciple and successor to the Royal Institution was Michael Faraday ( 1791 – 1867), who continued his teacher’s investigations. In an article published in 1834 , Faraday proposed his two well-known laws on electrolysis. The first affirms that the amount of substance that is deposited in an electrode is proportional to the amount of electrical charge that passes through the circuit. In his second law, Faraday states that the amount of electric charge that causes one gram of hydrogen to be released produces the release of an amount equal to the electrochemical equivalent of other substances.
The works carried out by Antoine Lavoisier ( 1743 – 1794 ) and Pierre Simon Laplace ( 1749 – 1827 ) are usually considered as the starting point of thermochemistry. They designed a new instrument, the calorimeter , in which he could make measurements of the amount of “caloric” released during chemical reactions. Laplace and Lavoisier thought that caloric was one of the imponderable elements and that gases were composed of caloric and the corresponding element. In the first half of the 19th century, the idea of caloric was abandoned and research began to be carried out that allowed the establishment of the laws ofthermodynamics . The application of these investigations to chemical processes allowed the emergence of thermochemistry, thanks to the work of authors such as Marcelin Berthelot (1827-1907) or Henry Le Châtelier ( 1850 – 1936 ).
One of the first works dedicated to the study of chemical kinetics was the investigations by Ludwig Ferdinand Wilhelmy ( 1812 – 1864 ) on the speed of configuration change of certain sugars in the presence of an acid . In the mid-19th century , Wilhelmy concluded that the rate of change was proportional to the concentration of sugar and acid and that it also varied with temperature . The collaboration between a chemist, George Vernon Harcourt ( 1834 – 1919), and a mathematician, William Esson (1838-1916), allowed the introduction of differential equations in the study of chemical kinetics. Esson was the introducer of the concepts of “first order” reactions, whose speed is proportional to the concentration of a single reagent, and of “second order” reactions, in which the speed is proportional to the product of two concentrations. In the last years of the 19th century, the works of Jacobus H. Van’t Hoff ( 1852 – 1911 ) had a great influence on this and other fields of chemistry . Among his contributions is the introduction of the “differential method” for the study of the speed of chemical reactions and its famousequation that allows to relate the speed and the temperature of the reaction.
The development of quantum mechanics and its application to the study of chemical phenomena has been one of the most notable changes that have occurred in twentieth century chemistry. Among the scientists who have made the most contributions in this regard is Linus Pauling, author of such significant books as his Introduction to Quantum Mechanics, With applications to Chemistry ( 1935 ) or The Nature of the Chemical Bond and the Structure of Molecules and Crystals ( 1939 ). Among many other contributions, Linus Carl Pauling was the introducer of the modern concept of electronegativity.
- Linus Carl Pauling
- Svante August Arrhenius
- Peter Debye
- Erich Hückel
- JH Van ‘t Hoff
- Lars Onsager
- Wilhelm Ostwald
- Paul J. Flory
- Jonathan Flower