A binary mixture of components a and b contains 1 mol a and 3 mol b in the liquid phase at 25°C and 0.50 bar. The excess Gibbs energy of the liquid mixture can be described by the van Laar equation with A = 4,010 [J/mol] and B = 2,501 [J/mol]. The saturation pressure of a is Psat a = 75 kPa.

(a) If this mixture is in equilibrium with vapor under these conditions, what is the vapor phase mole fraction of a?

(b) Determine the saturation pressure of b.

(c) Calculate the value of the Henry’s law constant for component a.