The chemical potential of a substance B in a mixture of substances B, C ... is related to the Gibbs energy \(G\) of the mixture by: \[\mu _{\rm{B}}=(\frac{\partial G}{\partial n_{\rm{B}}})_{T,p,n_{\rm{C}\neq \rm{B}}}\] where \(T\) is the thermodynamic temperature, \(p\) is the pressure and \(n_{\rm{B}}\), \(n_{\rm{C}}\), ... are the amounts of substance of B, C, ... . For a pure substance B, the chemical potential \(\mu _{\rm{B}}^{*}\) is given by: \[\mu _{\rm{B}}^{*}=\frac{G^{*}}{n_{\rm{B}}}=G_{\rm{m}}^{*}\] where \(G_{\rm{m}}^{*}\) is the molar Gibbs energy, and where the superscript * attached to a symbol denotes the property of the pure substance. The superscript \(^{⦵}\) or \(^{\circ}\) attached to a symbol may be used to denote a standard thermodynamic quantity.