A solution is prepared by mixing  moles of the solvent A with moles of the solute B. The s...

A solution is prepared by mixing  moles of the solvent A with moles of the solute B. The s stands for stoichiometric and indicates that these mole numbers need not be the number of moles of A and B actually present in the solution, since A and B may undergo reactions in the solution. In the solution, A and B react to form E and F according to

If b = 0, this reaction might be dissociation or association of the solvent. If b ≠ 0, the reaction might be solvation of the solute B. No E or F is added from the outside. Therefore, cind = c ‒ r ‒ a = 4‒1‒1 = 2.

Let and moles of A and B be added to the solution from outside. This addition shifts the reaction equilibrium to the right, and the extent of reaction changes by dξSince  for a reaction, the actual change in number of moles of A is The quantity  that occurs in the Gibbs equation for dG is  (a) Show that

provided reaction equilibrium is maintained. Thus we can take the sum over only the independent components A and B and ignore solvation, association, or dissociation, (b) Use the result of part (a) to show that