Consider a binary system of A and B where the molecular weight of A is three times that of B, MA = 3MB and where the mole fraction of A varies linearly as xA = z/3 for z = [0, 1].

1. (3 pts) Derive an equation for the mass fraction of A, wA. Express your answer in terms of z.

2. (2 pts) Plot xA, xB, wA and wB as functions of z. Clearly label your plot and include a legend. Comment on what you observe (note that you start with a linear profile for the mole fractions).