9.7 The flash point of a liquid or liquid mixture is the temperature above which the vapor mole fraction in surrounding air exceeds the lower flammability limit (LFL), and a flame will propagate across the surface of the liquid. The flashpoint of an aqueous binary mixture can be estimated using Raoult's law (providing Raoult's law is a valid approximation for the mixture). The flashpoint is determined by the vapor phase concentration as discussed in problem 9.6. The LFL for ethanol is 4.3\%, and for 2-propanol, 2.0\%. (Note: These problems are revisited again, modeling the solutions as non-ideal solutions in Chapter 11). (a) Use Raoult's law to estimate the flashpoint temperature at 760mmHg for 70mol% and 90mol% of the following solvents in liquid water: (i) ethanol; (ii) 2-propanol. (b) Use Raoult's law to estimate the liquid phase mol\% concentration of the solvent that would give a flashpoint of 22C at 760mmHg for: (i) ethanol; (ii) 2-propanol