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  2. Enthalpy - Wikipedia

    en.wikipedia.org/wiki/Enthalpy

    Enthalpy (/ ˈ ɛ n θ əl p i / ⓘ) is the sum of a thermodynamic system's internal energy and the product of its pressure and volume. [1] It is a state function in thermodynamics used in many measurements in chemical, biological, and physical systems at a constant external pressure, which is conveniently provided by the large ambient atmosphere.

  3. Laws of thermodynamics - Wikipedia

    en.wikipedia.org/wiki/Laws_of_thermodynamics

    It can be formulated in a variety of interesting and important ways. One of the simplest is the Clausius statement, that heat does not spontaneously pass from a colder to a hotter body. It implies the existence of a quantity called the entropy of a thermodynamic system. In terms of this quantity it implies that

  4. Bond energy - Wikipedia

    en.wikipedia.org/wiki/Bond_energy

    The bond dissociation energy (enthalpy) [4] is also referred to as bond disruption energy, bond energy, bond strength, or binding energy (abbreviation: BDE, BE, or D). It is defined as the standard enthalpy change of the following fission: R—X → R + X. The BDE, denoted by Dº(R—X), is usually derived by the thermochemical equation,

  5. Hess's law - Wikipedia

    en.wikipedia.org/wiki/Hess's_law

    The law states that the total enthalpy change during the complete course of a chemical reaction is independent of the sequence of steps taken. [2] [3] Hess's law is now understood as an expression of the fact that the enthalpy of a chemical process is independent of the path taken from the initial to the final state (i.e. enthalpy is a state ...

  6. Fundamental thermodynamic relation - Wikipedia

    en.wikipedia.org/wiki/Fundamental_thermodynamic...

    This is only one expression of the fundamental thermodynamic relation. It may be expressed in other ways, using different variables (e.g. using thermodynamic potentials). For example, the fundamental relation may be expressed in terms of the enthalpy H as = +

  7. Second law of thermodynamics - Wikipedia

    en.wikipedia.org/wiki/Second_law_of_thermodynamics

    This statement is the best-known phrasing of the second law. Because of the looseness of its language, e.g. universe, as well as lack of specific conditions, e.g. open, closed, or isolated, many people take this simple statement to mean that the second law of thermodynamics applies virtually to every subject imaginable. This is not true; this ...

  8. Thermochemical equation - Wikipedia

    en.wikipedia.org/wiki/Thermochemical_equation

    Enthalpy is the transfer of energy in a reaction (for chemical reactions, it is in the form of heat) and is the change in enthalpy. Δ H {\displaystyle \Delta H} is a state function, meaning that Δ H {\displaystyle \Delta H} is independent of processes occurring between initial and final states.

  9. Thermodynamic databases for pure substances - Wikipedia

    en.wikipedia.org/wiki/Thermodynamic_databases...

    Thermodynamic data is usually presented as a table or chart of function values for one mole of a substance (or in the case of the steam tables, one kg). A thermodynamic datafile is a set of equation parameters from which the numerical data values can be calculated. Tables and datafiles are usually presented at a standard pressure of 1 bar or 1 ...