You are interested in finding the pressure at which the first bubble of vapor will form from a liquid mixture of methanol (1) and 2-methyl1-propanol (2) (49% by mole methanol) at 508C. The Margules parameters for this mixture are A12 5 0.2565 and A21 5 0.2404 (Gmehling and Onken, 1977). Note that the vapor pressure of methanol is 422 mm Hg and that for 2-methyl-1-propanol is 56 mm Hg at 508C. Find the pressure and vapor-phase composition.