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In chemistry, bond energy (BE) is one measure of the strength of a chemical bond. It is sometimes called the mean bond, bond enthalpy, average bond enthalpy, or bond strength. [1][2][3] IUPAC defines bond energy as the average value of the gas-phase bond-dissociation energy (usually at a temperature of 298.15 K) for all bonds of the same type ...
The term bond-dissociation energy is similar to the related notion of bond-dissociation enthalpy (or bond enthalpy), which is sometimes used interchangeably.However, some authors make the distinction that the bond-dissociation energy (D 0) refers to the enthalpy change at 0 K, while the term bond-dissociation enthalpy is used for the enthalpy change at 298 K (unambiguously denoted DH° 298).
Hess's law. Hess’ law of constant heat summation, also known simply as Hess' law, is a relationship in physical chemistry and thermodynamics [1] named after Germain Hess, a Swiss -born Russian chemist and physician who published it in 1840. The law states that the total enthalpy change during the complete course of a chemical reaction is ...
The standard enthalpy of reaction (denoted ) for a chemical reaction is the difference between total product and total reactant molar enthalpies, calculated for substances in their standard states. The value can be approximately interpreted in terms of the total of the chemical bond energies for bonds broken and bonds formed.
The gravitational binding energy of an object, such as a celestial body, is the energy required to expand the material to infinity. If a body with the mass and radius of Earth were made purely of hydrogen-1, then the gravitational binding energy of that body would be about 0.391658 eV per atom. If a hydrogen-1 body had the mass and radius of ...
The Born–Haber cycle is an approach to analyze reaction energies. It was named after two German scientists, Max Born and Fritz Haber, who developed it in 1919. [1][2][3] It was also independently formulated by Kasimir Fajans [4] and published concurrently in the same journal. [1] The cycle is concerned with the formation of an ionic compound ...
The enthalpy of solution is most often expressed in kJ / mol at constant temperature. The energy change can be regarded as being made up of three parts: the endothermic breaking of bonds within the solute and within the solvent, and the formation of attractions between the solute and the solvent. An ideal solution has a null enthalpy of mixing.
In chemical thermodynamics, excess properties are properties of mixtures which quantify the non- ideal behavior of real mixtures. They are defined as the difference between the value of the property in a real mixture and the value that would exist in an ideal solution under the same conditions. The most frequently used excess properties are the ...