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This is true for all enthalpies of formation. The standard enthalpy of formation is measured in units of energy per amount of substance, usually stated in kilojoule per mole (kJ mol −1), but also in kilocalorie per mole, joule per mole or kilocalorie per gram (any combination of these units conforming to the energy per mass or amount guideline).
Regardless of the equation format, the heat of formation of a compound at any temperature is ΔH° form at 298.15 K, plus the sum of the heat content parameters of the products minus the sum of the heat content parameters of the reactants. The C p equation is obtained by taking the derivative of the heat content equation.
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.
Standard molar entropy, S o solid? J/(mol K) Heat capacity, c p? J/(mol K) Liquid properties Standard enthalpy change of formation, Δ f H o liquid: −460 kJ/mol Standard molar entropy, S o liquid: 166.9 J/(mol·K) Heat capacity, c p: 149.5 J/(mol·K) Gas properties Standard enthalpy change of formation, Δ f H o gas: −3955.4 kJ/mol Standard ...
of formation, Δ f H o solid? kJ/mol Standard molar entropy, S o solid? J/(mol K) Heat capacity, c p: 0.212 J/(mol K) at −200°C Liquid properties Std enthalpy change of formation, Δ f H o liquid: −318.2 kJ/mol Standard molar entropy, S o liquid: 180 J/(mol K) Heat capacity, c p: 2.68 J/(gK) at 20°C-25°C Gas properties Std enthalpy ...
Miedema described his motivation with "Reliable rules for the alloying behaviour of metals have long been sought. There is the qualitative rule that states that the greater the difference in the electronegativity of two metals, the greater the heat of formation - and hence the
The standard Gibbs free energy of formation (G f °) of a compound is the change of Gibbs free energy that accompanies the formation of 1 mole of a substance in its standard state from its constituent elements in their standard states (the most stable form of the element at 1 bar of pressure and the specified temperature, usually 298.15 K or 25 °C).
In thermochemistry, a thermochemical equation is a balanced chemical equation that represents the energy changes from a system to its surroundings. One such equation involves the enthalpy change, which is denoted with Δ H {\displaystyle \Delta H} In variable form, a thermochemical equation would appear similar to the following: