Physical Chemistry is the study of macroscopic, atomic, subatomic, and particle phenomena in chemical systems in terms of principles, practices, and concepts of physics such as motion, energy, force, time, thermodynamics, quantum. chemistry, statistical mechanics, analytical dynamics and chemical equilibrium.
Physical chemistry, in contrast to chemical physics, is predominantly (but not always) a macroscopic or supra-molecular science, since the majority of the principles on which it is based relate to the greater part of the molecular/atomic structure alone (eg, chemical and colloidal equilibrium).
Some relationships attempted to be solved by physical chemistry include the effects of:
- Intermolecular forces acting on the physical properties of the material (plasticity, tensile strength, surface tension in liquids).
- Reaction kinetics at the reaction rate.
- Identity of ion and electrical conductivity of material.
- The surface and electrochemical sciences of cell membranes.
- The interaction of one body with another in terms of the quantity of heat and work called thermodynamics.
- The heat transfer between a chemical system and its surroundings during a phase change or a chemical reaction that occurs is called a thermochemistry
- Study of the colligative nature of the number of species present in the solution.
- The number of phases, the number of components, and degrees of freedom (or variance) can be correlated with each other with the help of phase rules.
- Electrochemical cell reaction.
Video Physical chemistry
Main concept
The key concepts of physical chemistry are the ways in which pure physics is applied to chemical problems.
One of the key concepts in classical chemistry is that all chemical compounds can be described as groups of atoms that are bonded together and chemical reactions can be described as making and breaking those bonds. Predicting the properties of chemical compounds from atomic descriptions and how their bonds are one of the main goals of physical chemistry. To properly describe atoms and bonds, keep in mind both where the nuclei are, and how the electrons are distributed around them.
Quantum chemistry, a subfield of physical chemistry primarily concerned with the application of quantum mechanics to chemical matter, provides the means to determine how strong and what forms bonds, how the nucleus moves, and how light can be absorbed or emitted by chemical compounds. Spectroscopy is a sub-discipline of the physical chemistry associated with the interaction of electromagnetic radiation with matter.
Another important set of questions in chemistry deals with what kinds of reactions can occur spontaneously and which properties are possible for certain chemical mixtures. This is studied in chemical thermodynamics, which sets limits on the amount of how far the reaction can proceed, or how much energy can be converted into working in an internal combustion engine, and which provides the relationship between properties such as the coefficient of thermal expansion and the rate of change. entropy with pressure for gas or liquid. This can often be used to assess whether the reactor or engine design is feasible, or to check the validity of the experimental data. To some extent, quasi-equilibrium and non-equilibrium thermodynamics can represent irreversible change. However, classical thermodynamics is largely concerned with systems in balance and reversible change and not what actually happens, or how quickly, away from equilibrium.
Which reaction occurs and how quickly the subject of chemical kinetics, another branch of physical chemistry. A key idea in chemical kinetics is that for reactants to react and form products, most chemical species must go through a higher transition state in energy rather than reactant or product and serve as a barrier to reactions. In general, the higher the barrier, the slower the reaction. The second is that most chemical reactions occur as a series of elementary reactions, each with its own transition state. The key questions in kinetics include how the rate of the reaction depends on the temperature and concentration of the reactants and catalyst in the reaction mixture, as well as how the catalyst and reaction conditions can be engineered to optimize the reaction rate.
The fact that a rapid reaction occurs can often be determined only with some concentration and temperature, rather than needing to know all the positions and velocities of each molecule in the mix, is a special case of another key concept in physical chemistry, which is that as far as an engineer needs to know, occurs in a very large mixture of numbers (possibly from the order of the Avogadro constant, 6 x 10 23 ) can often be explained by only a few variables such as pressure, temperature, and concentration. The exact reason for this is described in statistical mechanics, specialization in physical chemistry which is also shared with physics. Statistical mechanics also provides a way to predict the properties we see in the daily life of molecular properties without relying on empirical correlations based on chemical similarities.
Maps Physical chemistry
History
The term "physical chemistry" was coined by Mikhail Lomonosov in 1752, when he gave a lecture entitled "The Course in True Physical Chemistry" (Russian: Ã, Â «??????????????? ? ??????????????????? in the opening of this lecture he gave a definition: "physical Chemistry is the science that must be explained under the terms of a physical experiment reasons for what is happening in the body complex through chemical operation ".
Modern physical chemistry originated in the 1860s to the 1880s by working on chemical thermodynamics, electrolytes in solution, chemical kinetics and other subjects. One milestone was a publication in 1876 by Josiah Willard Gibbs from his paper, On Equilibrium Heterogeneous Substance . This paper introduces several physical chemical foundations, such as Gibbs energy, chemical potential, and Gibbs phase rules. Other milestones include naming and accreditation of the next enthalpy for Heike Kamerlingh Onnes and the process of macromolecules.
The first scientific journal specifically in the field of physical chemistry is the German journal, Zeitschrift fÃÆ'¼r Physikalische Chemie , founded in 1887 by Wilhelm Ostwald and Jacobus Henricus van 't Hoff. Together with Svante August Arrhenius, these were prominent figures in physical chemistry in the late nineteenth and early twentieth centuries. All three were awarded the Nobel Prize in Chemistry between 1901-1909.
Developments in the following decades include the application of statistical mechanics to chemical systems and work on colloid and surface chemistry, in which Irving Langmuir makes many contributions. Another important step is the development of quantum mechanics into quantum chemistry from the 1930s, in which Linus Pauling was one of the leading names. Theoretical developments have been hand in hand with developments in experimental methods, where the use of various forms of spectroscopy, such as infrared spectroscopy, microwave spectroscopy, paramagnetic resonance of electrons and nuclear magnetic resonance spectroscopy, may be the most important 20th century developments.
Further developments in physical chemistry can be attributed to discoveries in nuclear chemistry, particularly in the separation of isotopes (before and during World War II), recent discoveries in astrochemistry, as well as the development of computational algorithms in the field of "additional physical properties". (almost all physicochemical properties, such as boiling point, tipping point, surface tension, vapor pressure, etc. - more than 20 overall - can be precisely calculated from chemical structures only, even if chemical molecules remain un-synthesized), and Herein lies the practical importance of contemporary physical chemistry.
See the Group's contribution method, Lydersen method, Joback method, Benson group improvement theory, quantitative activity-structure relationship
Journals
Several journals related to physical chemistry include Zeitschrift fÃÆ'¼r Physikalische Chemie (1887); Journal of Physical Chemistry A (from 1896 as Journal of Physical Chemistry , renamed in 1997); Chemical Physics of Chemical Physics (from 1999, formerly a Faraday Transaction with history dating from 1905); Macromolecular Chemistry and Physics (1947); Physical Chemical Annual Review (1950); Molecular Physics (1957); Journal of Organic Physical Chemistry (1988); Journal of Physical Chemistry B (1997); ChemPhysChem (2000); Journal of Physical Chemistry C (2007); and Journal of Physical Chemistry Letters (from 2010, a combination of letters previously published in separate journals)
Historical journals covering chemistry and physics include Annales de chimie et de physique (beginning in 1789, published under the name given here from 1815-1914).
See also
- List of important publications in chemistry # Physical chemistry
- List of unsolved issues in chemistry # Physical chemistry problems
- Physical Biochemistry
- Category: Physical chemist
References
External links
- The World of Physical Chemistry (Keith J. Laidler, 1993)
- Physical Chemistry from Ostwald to Pauling (John W. Servos, 1996)
- 100 Years of Physical Chemistry (Royal Society of Chemistry, 2004)
- Physical Chemistry: both Fish and Poultry? (Joachim Schummer, Chemical Autonomy , WÃÆ'¼rzburg, KÃÆ'¶nigshausen & Neumann, 1998, pp.Ã, 135-148)
- Cathedral of Science (Patrick Coffey, 2008)
- The Cambridge History of Science: Modern physics and mathematics (Mary Jo Nye, 2003)
Source of the article : Wikipedia
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