|
Gibbs Function
In thermodynamics, the Gibbs free energy (or Gibbs energy as the recommended name; symbol is a thermodynamic potential that can be used to calculate the maximum amount of work, other than pressure–volume work, that may be performed by a thermodynamically closed system at constant temperature and pressure. It also provides a necessary condition for processes such as chemical reactions that may occur under these conditions. The Gibbs free energy is expressed as G(p,T) = U + pV - TS = H - TS where: * U is the internal energy of the system * H is the enthalpy of the system * S is the entropy of the system * T is the temperature of the system * V is the volume of the system * p is the pressure of the system (which must be equal to that of the surroundings for mechanical equilibrium). The Gibbs free energy change (, measured in joules in SI) is the ''maximum'' amount of non-volume expansion work that can be extracted from a closed system (one that can exchange heat and work with i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermodynamics
Thermodynamics is a branch of physics that deals with heat, Work (thermodynamics), work, and temperature, and their relation to energy, entropy, and the physical properties of matter and radiation. The behavior of these quantities is governed by the four laws of thermodynamics, which convey a quantitative description using measurable macroscopic physical quantity, physical quantities but may be explained in terms of microscopic constituents by statistical mechanics. Thermodynamics applies to various topics in science and engineering, especially physical chemistry, biochemistry, chemical engineering, and mechanical engineering, as well as other complex fields such as meteorology. Historically, thermodynamics developed out of a desire to increase the thermodynamic efficiency, efficiency of early steam engines, particularly through the work of French physicist Nicolas Léonard Sadi Carnot, Sadi Carnot (1824) who believed that engine efficiency was the key that could help France win ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Josiah Willard Gibbs
Josiah Willard Gibbs (; February 11, 1839 – April 28, 1903) was an American mechanical engineer and scientist who made fundamental theoretical contributions to physics, chemistry, and mathematics. His work on the applications of thermodynamics was instrumental in transforming physical chemistry into a rigorous deductive science. Together with James Clerk Maxwell and Ludwig Boltzmann, he created statistical mechanics (a term that he coined), explaining the laws of thermodynamics as consequences of the statistical properties of ensembles of the possible states of a physical system composed of many particles. Gibbs also worked on the application of Maxwell's equations to problems in physical optics. As a mathematician, he created modern vector calculus (independently of the British scientist Oliver Heaviside, who carried out similar work during the same period) and described the Gibbs phenomenon in the theory of Fourier analysis. In 1863, Yale University awarded Gibbs the firs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclohexanol
Cyclohexanol is the organic compound with the formula HOCH(CH2)5. The molecule is related to cyclohexane by replacement of one hydrogen atom by a hydroxyl group. This compound exists as a deliquescent colorless solid with a camphor-like odor, which, when very pure, melts near room temperature. Millions of tonnes are produced annually, mainly as a precursor to nylon.Michael Tuttle Musser "Cyclohexanol and Cyclohexanone" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005. Production Cyclohexanol is produced by the oxidation of cyclohexane in air, typically using cobalt catalysts: :2 C6H12 + O2 → 2 C6H11OH This process coforms cyclohexanone, and this mixture ("KA oil" for ketone-alcohol oil) is the main feedstock for the production of adipic acid. The oxidation involves radicals and the intermediacy of the hydroperoxide C6H11O2H. Alternatively, cyclohexanol can be produced by the hydrogenation of phenol: :C6H5OH + 3 H2 → C6H11OH This process can al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elimination Reaction
An elimination reaction is a type of organic reaction in which two substituents are removed from a molecule in either a one- or two-step mechanism. The one-step mechanism is known as the E2 reaction, and the two-step mechanism is known as the E1 reaction. The numbers refer not to the number of steps in the mechanism, but rather to the kinetics of the reaction: E2 is bimolecular (second-order) while E1 is unimolecular (first-order). In cases where the molecule is able to stabilize an anion but possesses a poor leaving group, a third type of reaction, E1cB-elimination reaction, E1CB, exists. Finally, the pyrolysis of xanthate and acetate esters proceed through an "internal" elimination mechanism, the Ei mechanism, Ei mechanism. E2 mechanism The E2 mechanism, where E2 stands for bimolecular elimination, involves a one-step mechanism in which ''carbon-hydrogen'' and ''carbon-halogen'' bonds break to form a double bond (''C=C molecular geometry, Pi bond''). The specifics of the re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endergonic Reaction
In chemical thermodynamics, an endergonic reaction (; also called a heat absorbing nonspontaneous reaction or an unfavorable reaction) is a chemical reaction in which the standard change in free energy is positive, and an additional driving force is needed to perform this reaction. In layman's terms, the total amount of useful energy is negative (it takes more energy to start the reaction than what is received out of it) so the total energy is a net negative result, as opposed to a net positive result in an exergonic reaction. Another way to phrase this is that useful energy must be absorbed from the surroundings into the workable system for the reaction to happen. Under constant temperature and constant pressure conditions, this means that the change in the standard Gibbs free energy would be positive, :\Delta G^\circ > 0 for the reaction at standard state (i.e. at standard pressure (1 bar), and standard concentrations (1 molar) of all the reagents). In metabolism, an e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exergonic Process
An exergonic process is one which there is a positive flow of energy from the system to the surroundings. This is in contrast with an endergonic process. Constant pressure, constant temperature reactions are exergonic if and only if the Gibbs free energy change is negative (∆''G'' < 0). "Exergonic" (from the prefix exo-, derived for the Greek word ἔξω ''exō'', "outside" and the suffix -ergonic, derived from the Greek word ἔργον ''ergon'', "") means "releasing energy in the form of work". In thermodynamics, work is defined as the energy moving from the (the internal region) to the |
Second Law Of Thermodynamics
The second law of thermodynamics is a physical law based on Universal (metaphysics), universal empirical observation concerning heat and Energy transformation, energy interconversions. A simple statement of the law is that heat always flows spontaneously from hotter to colder regions of matter (or 'downhill' in terms of the temperature gradient). Another statement is: "Not all heat can be converted into Work (thermodynamics), work in a cyclic process."Young, H. D; Freedman, R. A. (2004). ''University Physics'', 11th edition. Pearson. p. 764. The second law of thermodynamics establishes the concept of entropy as a physical property of a thermodynamic system. It predicts whether processes are forbidden despite obeying the requirement of conservation of energy as expressed in the first law of thermodynamics and provides necessary criteria for spontaneous processes. For example, the first law allows the process of a cup falling off a table and breaking on the floor, as well as allowi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diamond
Diamond is a Allotropes of carbon, solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. Diamond is tasteless, odourless, strong, brittle solid, colourless in pure form, a poor conductor of electricity, and insoluble in water. Another solid form of carbon known as graphite is the Chemical stability, chemically stable form of carbon at Standard temperature and pressure, room temperature and pressure, but diamond is metastable and converts to it at a negligible rate under those conditions. Diamond has the highest Scratch hardness, hardness and thermal conductivity of any natural material, properties that are used in major industrial applications such as cutting and polishing tools. Because the arrangement of atoms in diamond is extremely rigid, few types of impurity can contaminate it (two exceptions are boron and nitrogen). Small numbers of lattice defect, defects or impurities (about one per million of lattice atoms) can color ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermodynamic Temperature
Thermodynamic temperature, also known as absolute temperature, is a physical quantity which measures temperature starting from absolute zero, the point at which particles have minimal thermal motion. Thermodynamic temperature is typically expressed using the Kelvin scale, where the unit of measurement is the ''kelvin'' (unit symbol: K). The Kelvin scale uses the same degree interval as the Celsius scale but is offset so that 0 K corresponds to absolute zero. For comparison, a temperature of 295 K corresponds to 21.85 °C and 71.33 °F. Another absolute scale of temperature is the Rankine scale, which is based on the Fahrenheit degree interval. Historically, thermodynamic temperature was defined by Lord Kelvin in terms of a macroscopic relation between Work (thermodynamics), thermodynamic work and Heat, heat transfer as defined in thermodynamics, but the kelvin was redefined by international agreement in 2019 in terms of phenomena that are now understood as man ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Standard State
The standard state of a material (pure substance, mixture or solution) is a reference point used to calculate its properties under different conditions. A degree sign (°) or a superscript ⦵ symbol (⦵) is used to designate a thermodynamic quantity in the standard state, such as change in enthalpy (Δ''H''°), change in entropy (Δ''S''°), or change in Gibbs free energy (Δ''G''°). The degree symbol has become widespread, although the Plimsoll is recommended in standards, see discussion about typesetting below. In principle, the choice of standard state is arbitrary, although the International Union of Pure and Applied Chemistry (IUPAC) recommends a conventional set of standard states for general use. The standard state should not be confused with standard temperature and pressure (STP) for gases, nor with the standard solutions used in analytical chemistry. STP is commonly used for calculations involving gases that approximate an ideal gas, whereas standard state condit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
On The Equilibrium Of Heterogeneous Substances
In the history of thermodynamics, "On the Equilibrium of Heterogeneous Substances" is a 300-page paper written by American chemical physicist Willard Gibbs. It is one of the founding papers in thermodynamics, along with German physicist Hermann von Helmholtz's 1882 paper "'' Thermodynamik chemischer Vorgänge''." Together they form the foundation of chemical thermodynamics as well as a large part of physical chemistry. Gibbs's paper marked the beginning of chemical thermodynamics by integrating chemical, physical, electrical, and electromagnetic phenomena into a coherent system. It introduced concepts such as chemical potential, phase rule, and more, which form the basis for modern physical chemistry. American writer Bill Bryson describes Gibbs's paper as "the '' Principia'' of thermodynamics". "On the Equilibrium of Heterogeneous Substances", was originally published in a relatively obscure American journal, the '' Transactions of the Connecticut Academy of Arts and Sciences ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Masterpiece
A masterpiece, , or ; ; ) is a creation that has been given much critical praise, especially one that is considered the greatest work of a person's career or a work of outstanding creativity, skill, profundity, or workmanship. Historically, a "masterpiece" was a work of a very high standard produced by an apprentice to obtain full membership, as a "master", of a guild or academy in various areas of the visual arts and crafts. Etymology The form ''masterstik'' is recorded in English or Scots in a set of Aberdeen guild regulations dated to 1579, whereas ''masterpiece'' is first found in 1605, already outside a guild context, in a Ben Jonson play. ''Masterprize'' was another early variant in English. In English, the term rapidly became used in a variety of contexts for an exceptionally good piece of creative work, and was "in early use, often applied to man as the 'masterpiece' of God or Nature". History Originally, the term ''masterpiece'' referred to a piece of work ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
