... constancy of S and V, S and p, T and V, and T and p, when using the differentials dU, dH, dA, and dG, respectively. In most cases the conditions of constant T and V or constant T and p are most ... Helmholtz energy AUTS (13) and the Gibbs energy G U pV TS H TS A pV ( 14) Since U is a function of state, and p, V, T, and S are state variables, H, A, and G are also functions of ... and extensive properties are pressure p and volume V, interfacial tension γ and interfacial area A, electric potential Ψ and electric charge Q, the chemical potential µi of component i, and...