Question 4 Answer all parts. (a) Consider a two-component system consisting of a mixture of substances A and B, and recall the fundamental equation of chemical thermodynamics describing this system (i.e. the variation of Gibbs energy. dg, with pressure, temperature and composition). Mathematically derive and define the chemical potential of substance A as the variation of the enthalpy H with composition: in your answer define all the terms in the partial differential equation describing this. 110 marks