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Quantity (common name/s) (Common) symbol/s Defining equation SI unit Dimension General heat/thermal capacity C = / J⋅K −1: ML 2 T −2 Θ −1: Heat capacity (isobaric)
In chemical thermodynamics, the reaction quotient (Q r or just Q) [1] is a dimensionless quantity that provides a measurement of the relative amounts of products and reactants present in a reaction mixture for a reaction with well-defined overall stoichiometry at a particular point in time.
Here Q and W are heat and work added, with no restrictions as to whether the process is reversible, quasistatic, or irreversible.[Warner, Am. J. Phys., 29, 124 (1961)] [34] This statement by Crawford, for W, uses the sign convention of IUPAC, not that of Clausius. Though it does not explicitly say so, this statement refers to closed systems.
where W is work, U is internal energy, and Q is heat. [1] Pressure-volume work by the closed system is defined as: = where Δ means change over the whole process, whereas d denotes a differential. Since pressure is constant, this means that =. Applying the ideal gas law, this becomes
From the first law of thermodynamics, =, where W is the work done by the system. When only expansion work is possible for a process we have Δ U = Q V {\displaystyle \Delta U=Q_{V}} ; this implies that the heat of reaction at constant volume is equal to the change in the internal energy Δ U {\displaystyle \Delta U} of the reacting system.
The symbol Q for heat was introduced by Rudolf Clausius and Macquorn Rankine in c. 1859. [4] Heat released by a system into its surroundings is by convention, as a contributor to internal energy, a negative quantity (Q < 0); when a system absorbs heat from its surroundings, it is positive (Q > 0).
Also acid ionization constant or acidity constant. A quantitative measure of the strength of an acid in solution expressed as an equilibrium constant for a chemical dissociation reaction in the context of acid-base reactions. It is often given as its base-10 cologarithm, p K a. acid–base extraction A chemical reaction in which chemical species are separated from other acids and bases. acid ...
For Faraday's first law, M, F, v are constants; thus, the larger the value of Q, the larger m will be. For Faraday's second law, Q, F, v are constants; thus, the larger the value of (equivalent weight), the larger m will be. In the simple case of constant-current electrolysis, Q = It, leading to