|
RRKM Theory
The Rice–Ramsperger–Kassel–Marcus (RRKM) theory is a theory of chemical reactivity. It was developed by Rice and Ramsperger in 1927 and Kassel in 1928 (RRK theory) and generalized (into the RRKM theory) in 1952 by Marcus who took the transition state theory developed by Eyring in 1935 into account. These methods enable the computation of simple estimates of the unimolecular reaction rates from a few characteristics of the potential energy surface. Assumption Assume that the molecule consists of harmonic oscillators, which are connected and can exchange energy with each other. * Assume the possible excitation energy of the molecule to be , which enables the reaction to occur. * The rate of intra-molecular energy distribution is much faster than that of reaction itself. * As a corollary to the above, the potential energy surface does not have any "bottlenecks" for which certain vibrational modes may be trapped for longer than the average time of the reaction Deri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reactivity (chemistry)
In chemistry, reactivity is the impulse for which a chemical substance undergoes a chemical reaction, either by itself or with other materials, with an overall release of energy. ''Reactivity'' refers to: * the chemical reactions of a single substance, * the chemical reactions of two or more substances that interact with each other, * the systematic study of sets of reactions of these two kinds, * methodology that applies to the study of reactivity of chemicals of all kinds, * experimental methods that are used to observe these processes, and * theories to predict and to account for these processes. The chemical reactivity of a single substance (reactant) covers its behavior in which it: * decomposes, * forms new substances by addition of atoms from another reactant or reactants, and * interacts with two or more other reactants to form two or more products. The chemical reactivity of a substance can refer to the variety of circumstances (conditions that include temperature, pre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oscar Knefler Rice
Oscar, OSCAR, or The Oscar may refer to: People and fictional and mythical characters * Oscar (given name), including lists of people and fictional characters named Oscar, Óscar or Oskar * Oscar (footballer, born 1954), Brazilian footballer José Oscar Bernardi * Oscar (footballer, born 1991), Brazilian footballer Oscar dos Santos Emboaba Júnior * Oscar (Irish mythology), son of Oisín and grandson of Finn mac Cumhall Places in the United States * Oscar, Kentucky, an unincorporated community * Oscar, Louisiana, an unincorporated community * Oscar, Missouri, an unincorporated community * Oscar, Oklahoma, an unincorporated community * Oscar, Pennsylvania, an unincorporated community * Oscar, Texas, an unincorporated community * Oscar, West Virginia, an unincorporated community * Oscar Township, Otter Tail County, Minnesota, a civil township * Lake Oscar (other) Animals * Oscar (bionic cat), a cat that had implants after losing both hind paws * Oscar (bull) (d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Herman Carl Ramsperger
Herman may refer to: People * Herman (name), list of people with this name * Saint Herman (other) * Peter Noone (born 1947), known by the mononym Herman Places in the United States * Herman, Arkansas * Herman, Michigan * Herman, Minnesota * Herman, Nebraska * Herman, Pennsylvania * Herman, Dodge County, Wisconsin * Herman, Shawano County, Wisconsin * Herman, Sheboygan County, Wisconsin Place in India * Herman, Shopian Other uses * ''Herman'' (comic strip) * ''Herman'' (film), a 1990 Norwegian film * Herman Building, a historic building in Hollywood, California * Herman the Bull, a bull used for genetic experiments in the controversial lactoferrin project of GenePharming, Netherlands * Herman the Clown (), a Finnish TV clown from children's TV show performed by Veijo Pasanen * Herman's Hermits, a British pop combo * Herman cake (also called Hermann), a type of sourdough bread starter or Amish Friendship Bread starter * ''Herman'' (album) by 't Hof Van Commerce See ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Louis Stevenson Kassel
Louis may refer to: People * Louis (given name), origin and several individuals with this name * Louis (surname) * Louis (singer), Serbian singer Other uses * Louis (coin), a French coin * HMS ''Louis'', two ships of the Royal Navy See also * Derived terms * King Louis (other) * Saint Louis (other) * Louis Cruise Lines * Louis dressing, for salad * Louis Quinze, design style Associated terms * Lewis (other) * Louie (other) * Luis (other) * Louise (other) * Louisville (other) Associated names * * Chlodwig, the origin of the name Ludwig, which is translated to English as "Louis" * Ladislav and László - names sometimes erroneously associated with "Louis" * Ludovic, Ludwig, Ludwick, Ludwik Ludwik () is a Polish given name. Notable people with the name include: * Ludwik Czyżewski, Polish WWII general * Ludwik Fleck (1896–1961), Polish medical doctor and biologist * Ludwik Gintel (1899–1973), Polish-Israeli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rudolph A
Rudolph or Rudolf may refer to: People * Rudolph (name), the given name including a list of people with the name Religious figures * Rudolf of Fulda (died 865), 9th century monk, writer and theologian * Rudolf von Habsburg-Lothringen (1788–1831), Archbishop of Olomouc and member of the House of Habsburg-Lorraine Royalty and nobility *Rudolph I (other) * Rudolph II (other) * Rudolph III (other) * Rudolph of France (died 936) * Rudolph I of Germany (1218–1291) * Rudolf II, Holy Roman Emperor (1552–1612) * Rudolph, Prince of Anhalt-Zerbst (1576–1621) * Rudolf, Crown Prince of Austria (1858–1889), son and heir of Emperor Franz Joseph I of Austria and Empress Elisabeth of Austria (died at Mayerling) Places * Rudolph Glacier, Antarctica * Rudolph, South Dakota, US * Rudolph, Wisconsin, US, a village * Rudolph (town), Wisconsin, adjacent to the village * Rudolf Island, northernmost island of Europe * Lake Rudolf, now Lake Turkana, in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transition State Theory
In chemistry, transition state theory (TST) explains the reaction rates of elementary chemical reactions. The theory assumes a special type of chemical equilibrium (quasi-equilibrium) between reactants and activated transition state complexes. TST is used primarily to understand qualitatively how chemical reactions take place. TST has been less successful in its original goal of calculating absolute reaction rate constants because the calculation of absolute reaction rates requires precise knowledge of potential energy surfaces, but it has been successful in calculating the standard enthalpy of activation (Δ''H''‡, also written Δ‡''H''ɵ), the standard entropy of activation (Δ''S''‡ or Δ‡''S''ɵ), and the standard Gibbs energy of activation (Δ''G''‡ or Δ‡''G''ɵ) for a particular reaction if its rate constant has been experimentally determined (the ‡ notation refers to the value of interest ''at the transition state''; Δ''H''‡ is the difference between the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Henry Eyring (chemist)
Henry Eyring (February 20, 1901 – December 26, 1981) was a Mexico-born United States theoretical chemist whose primary contribution was in the study of chemical reaction rates and intermediates. Eyring developed the Absolute Rate Theory or Transition state theory of chemical reactions, connecting the fields of chemistry and physics through atomic theory, quantum theory, and statistical mechanics. History Eyring, a third-generation member of the Church of Jesus Christ of Latter-day Saints (LDS Church), was reared on a cattle ranch in Colonia Juárez, Chihuahua, a Mormon colony, for the first 11 years of his life. His father, Edward Christian Eyring, practiced plural marriage; Edward married Caroline Romney (1893) and her sister Emma Romney (1903), both daughters of Miles Park Romney, the great-grandfather of Mitt Romney. In July 1912, the Eyrings and about 4,200 other immigrants were driven out of Mexico by violent insurgents during the Mexican Revolution and moved to El P ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reaction Rates
The reaction rate or rate of reaction is the speed at which a chemical reaction takes place, defined as proportional to the increase in the concentration of a product per unit time and to the decrease in the concentration of a reactant per unit time. Reaction rates can vary dramatically. For example, the oxidative rusting of iron under Earth's atmosphere is a slow reaction that can take many years, but the combustion of cellulose in a fire is a reaction that takes place in fractions of a second. For most reactions, the rate decreases as the reaction proceeds. A reaction's rate can be determined by measuring the changes in concentration over time. Chemical kinetics is the part of physical chemistry that concerns how rates of chemical reactions are measured and predicted, and how reaction-rate data can be used to deduce probable reaction mechanisms. The concepts of chemical kinetics are applied in many disciplines, such as chemical engineering, enzymology and environmental en ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potential Energy Surface
A potential energy surface (PES) or energy landscape describes the energy of a Physical system, system, especially a collection of atoms, in terms of certain Parameter, parameters, normally the positions of the atoms. The Surface (mathematics), surface might define the energy as a Function (mathematics), function of one or more coordinates; if there is only one coordinate, the surface is called a ''potential energy curve'' or energy profile. An example is the Morse/Long-range potential. It is helpful to use the analogy of a landscape: for a system with two Degrees of freedom (physics and chemistry), degrees of freedom (e.g. two bond lengths), the value of the energy (analogy: the height of the land) is a function of two bond lengths (analogy: the coordinates of the position on the ground). The PES concept finds application in fields such as physics, chemistry and biochemistry, especially in the theoretical sub-branches of these subjects. It can be used to theoretically explore p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Harmonic Oscillators
In classical mechanics, a harmonic oscillator is a system that, when displaced from its equilibrium position, experiences a restoring force ''F'' proportional to the displacement ''x'': \vec F = -k \vec x, where ''k'' is a positive constant. The harmonic oscillator model is important in physics, because any mass subject to a force in stable equilibrium acts as a harmonic oscillator for small vibrations. Harmonic oscillators occur widely in nature and are exploited in many manmade devices, such as clocks and radio circuits. If ''F'' is the only force acting on the system, the system is called a simple harmonic oscillator, and it undergoes simple harmonic motion: sinusoidal oscillations about the equilibrium point, with a constant amplitude and a constant frequency (which does not depend on the amplitude). If a frictional force (damping) proportional to the velocity is also present, the harmonic oscillator is described as a damped oscillator. Depending on the friction coef ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reaction Coordinate
In chemistry, a reaction coordinate is an abstract one-dimensional coordinate chosen to represent progress along a reaction pathway. Where possible it is usually a geometric parameter that changes during the conversion of one or more molecular entity, molecular entities, such as bond length or bond angle. For example, in the homolysis (chemistry), homolytic dissociation of molecular hydrogen, an apt choice would be the coordinate corresponding to the bond length. Non-geometric parameters such as Bond order#Non-integer bond orders, bond order are also used, but such direct representation of the reaction process can be difficult, especially for more complex reactions. In computer simulations collective variables are employed for a target-oriented sampling approach. Plain simulations fail to capture so called rare events, because they are not feasible to occur in realistic computation times. This often stems from to high energy barriers separating the reactants from products, or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transition State Theory
In chemistry, transition state theory (TST) explains the reaction rates of elementary chemical reactions. The theory assumes a special type of chemical equilibrium (quasi-equilibrium) between reactants and activated transition state complexes. TST is used primarily to understand qualitatively how chemical reactions take place. TST has been less successful in its original goal of calculating absolute reaction rate constants because the calculation of absolute reaction rates requires precise knowledge of potential energy surfaces, but it has been successful in calculating the standard enthalpy of activation (Δ''H''‡, also written Δ‡''H''ɵ), the standard entropy of activation (Δ''S''‡ or Δ‡''S''ɵ), and the standard Gibbs energy of activation (Δ''G''‡ or Δ‡''G''ɵ) for a particular reaction if its rate constant has been experimentally determined (the ‡ notation refers to the value of interest ''at the transition state''; Δ''H''‡ is the difference between the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
