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All elements in their reference states (oxygen gas, solid carbon in the form of graphite, etc.) have a standard enthalpy of formation of zero, as there is no change involved in their formation. The formation reaction is a constant pressure and constant temperature process. Since the pressure of the standard formation reaction is fixed at 1 bar ...
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.
Ammonium chloride is an inorganic chemical compound with the chemical formula N H 4 Cl, also written as [NH 4]Cl.It is an ammonium salt of hydrogen chloride.It consists of ammonium cations [NH 4] + and chloride anions Cl −.
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 ...
Standard enthalpy of combustion is the enthalpy change when one mole of an organic compound reacts with molecular oxygen (O 2) to form carbon dioxide and liquid water. For example, the standard enthalpy of combustion of ethane gas refers to the reaction C 2 H 6 (g) + (7/2) O 2 (g) → 2 CO 2 (g) + 3 H 2 O (l).
The definition of the Gibbs function is = + where H is the enthalpy defined by: = +. Taking differentials of each definition to find dH and dG, then using the fundamental thermodynamic relation (always true for reversible or irreversible processes): = where S is the entropy, V is volume, (minus sign due to reversibility, in which dU = 0: work other than pressure-volume may be done and is equal ...
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.
The Van 't Hoff equation relates the change in the equilibrium constant, K eq, of a chemical reaction to the change in temperature, T, given the standard enthalpy change, Δ r H ⊖, for the process. The subscript r {\displaystyle r} means "reaction" and the superscript ⊖ {\displaystyle \ominus } means "standard".