Question

Thermodynamics: Consider the equilibrium reaction A(g) + B(g) -><- C(g)+D(g). At T=298 K, the standard enthalpies of formation of the components in the gas phase are -20, -40, -30, and -10 kJ/mol for A,B,C, and D, respectively. The standard-state entropies of the components in the gas phase are 30, 50, 50, and 80 J/(mol K), in the same order. The vapor pressure of liquid C at this temperature is 0.1 bar, while all other components are volatile gases with Henry's Law constants in liquid C equal to Ha=1000 bar, Hb=2000 bar, and Hd=800 bar.

(a) How many phases are present at equilibrium when starting from an equimolar mixture of A+B (no C or D) at constant T=298 K and P=1 bar?

(b) Obtain the equilibrium composition of all phases present for the mixture of part (a).

(c) Calculate the standard Gibbs free energy change for the equilibrium reaction A(g) + B(g)-><-C(l)+D(g) at T=298 K, where C(l) is component C in the liquid phase.

Answer 1