SUMMARY / RELATED TOPICS

Physical chemistry

Physical chemistry is the study of macroscopic, atomic and particulate phenomena in chemical systems in terms of the principles and concepts of physics such as motion, force, thermodynamics, quantum chemistry, statistical mechanics, analytical dynamics and chemical equilibrium. Physical chemistry, in contrast to chemical physics, is predominantly a macroscopic or supra-molecular science, as the majority of the principles on which it was founded relate to the bulk rather than the molecular/atomic structure alone; some of the relationships that physical chemistry strives to resolve include the effects of: Intermolecular forces that act upon the physical properties of materials. Reaction kinetics on the rate of a reaction; the identity of ions and the electrical conductivity of materials. Surface science and electrochemistry of cell membranes. Interaction of one body with another in terms of quantities of heat and work called thermodynamics. Transfer of heat between a chemical system and its surroundings during change of phase or chemical reaction taking place called thermochemistry Study of colligative properties of number of species present in solution.

Number of phases, number of components and degree of freedom can be correlated with one another with help of phase rule. Reactions of electrochemical cells; 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 bonded together and chemical reactions can be described as the making and breaking of those bonds. Predicting the properties of chemical compounds from a description of atoms and how they bond is one of the major goals of physical chemistry. To describe the atoms and bonds it is necessary to know both where the nuclei of the atoms are, how electrons are distributed around them. Quantum chemistry, a subfield of physical chemistry concerned with the application of quantum mechanics to chemical problems, provides tools to determine how strong and what shape bonds are, how nuclei move, how light can be absorbed or emitted by a chemical compound.

Spectroscopy is the related sub-discipline of physical chemistry, concerned with the interaction of electromagnetic radiation with matter. Another set of important questions in chemistry concerns what kind of reactions can happen spontaneously and which properties are possible for a given chemical mixture; this is studied in chemical thermodynamics, which sets limits on quantities like how far a reaction can proceed, or how much energy can be converted into work in an internal combustion engine, which provides links between properties like the thermal expansion coefficient and rate of change of entropy with pressure for a gas or a liquid. It can be used to assess whether a reactor or engine design is feasible, or to check the validity of experimental data. To a limited extent, quasi-equilibrium and non-equilibrium thermodynamics can describe irreversible changes. However, classical thermodynamics is concerned with systems in equilibrium and reversible changes and not what does happen, or how fast, away from equilibrium.

Which reactions do occur and how fast is 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 transition states which are higher in energy than either the reactants or the products and serve as a barrier to reaction. In general, the higher the barrier, the slower the reaction. A second is that most chemical reactions occur as a sequence of elementary reactions, each with its own transition state. Key questions in kinetics include how the rate of reaction depends on temperature and on the concentrations of reactants and catalysts in the reaction mixture, as well as how catalysts and reaction conditions can be engineered to optimize the reaction rate; the fact that how fast reactions occur can be specified with just a few concentrations and a temperature, instead of needing to know all the positions and speeds of every molecule in a mixture, is a special case of another key concept in physical chemistry, that to the extent an engineer needs to know, everything going on in a mixture of large numbers of particles can be described by just a few variables like pressure and concentration.

The precise reasons for this are described in statistical mechanics, a specialty within physical chemistry, shared with physics. Statistical mechanics provides ways to predict the properties we see in everyday life from molecular properties without relying on empirical correlations based on chemical similarities; the term "physical chemistry" was coined by Mikhail Lomonosov in 1752, when he presented a lecture course entitled "A Course in True Physical Chemistry" before the students of Petersburg University. In the preamble to these lectures he gives the definition: "Physical chemistry is the science that must explain under provisions of physical experiments the reason for what is happening in complex bodies through chemical operations". Modern physical chemistry originated in the 1860s to 1880s with work on chemical thermodynamics, electrolytes in solutions, chemical kinetics and other subjects. One milestone was the publication in 1876 by Josiah Willard Gibbs of his paper, On the Equilibrium of Heterogeneous Substances.

This paper introduced several of the cornerstones of physical chemistr

1962 in Singapore

The following lists events that happened during 1962 in Singapore. Yang di-Pertuan Negara - Yusof Ishak Prime Minister - Lee Kuan Yew 10 April - The SEACOM cable is announced. 1 September - A referendum is held in Singapore to vote on merger with Malaysia. In the end, 70 percent of votes chose merger in accordance with the terms of the 1961 White Paper. 6 February - Eleanor Wong - Lawyer, playwright. 29 May - Fandi Ahmad - Former football player. 14 June - S. Iswaran - Minister of Communications and Information 27 October - Ang Peng Siong - Former swimmer. Olivia Lum - Hyflux CEO. Jennifer Tham Sow Ying - Conductor of Singapore Youth Choir. K. F. Seetoh - Food personality, creator of Makansutra. Madeleine Lee - Investment manager, poet. 21 August - Ahmad bin Ibrahim, Member of Parliament

Shulamit Gross

Shulamit Gross was an Israeli mineralogist and geologist who studied the Hatrurim Formation. Gross was born as Shulamit Lifszyc in Poland, she was the daughter of Mejer Lifszyc. She studied in the local Tarbut school, on at the Belarusian State Polytechnic Institute in Minsk; when Nazi Germany invaded the Soviet Union during the summer of 1941, she fled to Tashkent in Uzbekistan. Here she continued her studies in the faculty of geology, which she graduated cum laude in 1945, her parents died in the Treblinka extermination camp in 1943. She began a PhD in the Radioactive Micas of Central Asia, but was not permitted KGB security clearance, her studies were terminated. After graduating, she moved to Lomonosov University in Moscow to conduct research in crystallography, her second project considered the "The ionic radius affect on lattice structure and mineral properties”. In 1950 she immigrated to Israel with her husband, the film director Natan Gross, their baby, who became a film director in his adult life as well.

Gross was known for her research on the mineralogy of the Hatrurim Formation. In 1958 she began working at the Israel Atomic Energy Commission. During the 1960s, a group of scientists from the Hebrew University of Jerusalem, including Yaakov Ben-Tor, Lisa Heller-Kallai, discovered the unique mineral assemblage found in the Hatrurim Formation, she moved to the Israeli Geological Society in 1961. She became a PhD candidate at the Hebrew University of Jerusalem in 1964, working on "The Mineralogy of the Hatrurim Formation, Israel". A mineralogical analysis revealed that the rocks contain common minerals such as diopside, garnet, anorthite, as well as rare minerals such as spurrite, brownmillerite and larnite; these rare minerals only form at high temperatures, for example in places where siliceous limestones are contact-metamorphosed by volcanic rocks. These minerals are common in man-made Portland cement, used in the construction industry; the manufacturing of Portland cement involves a similar process: heating of limestone or chalk with siliceous clay at high temperatures.

She continued to study the minerals and in 1977 published a monograph describing 123 mineral species discovered in the Hatrurim Formation. Five were known only from a single locality, eight others were known only as synthetic products of the cement industry. Gross discovered several minerals new to science: bentorite, ye’elimite, hatrurite. A fourth mineral discovered by Gross was only described by Dietmar Weber and Adolf Bischoff, which they named grossite after Shulamit, she demonstrated that the unique mineral assemblage of the Hatrurim Formation formed by pyrometamorphism, she managed to recreate most of the minerals by heating the precursor sedimentary rocks of the Ghareb and Taqiye formations. Her discoveries earned her the inaugural Rafael Freund Award of the Israeli Geological Society in 1979, she became an honorary member of the Israel Geological Society in 1986. An additional mineral discovered in the Hatrurim Formation was named shulamitite in 2011, she died on September 18, 2012