The (1) + (2) system forms an azeotrope at x₁ + 0.75 and 80°C. At 80°C, P₁^sat = 600 mmHg, P₂^sat = 900 mmHg. The liquid phase can be modeled by the van Laar model.

(a) Estimate the activity coefficient of component 1 at x₁ = 0.75 and 80°C.

(b) Qualitatively sketch the P-x-y and T-x-y diagrams that you expect.