A liquid mixture containing 50 mole% propane, 30% n-butane, and 20% isobutene is stored in a rigid container at 77°F. The container has a maximum allowable working pressure of 200 psig. The head space above the liquid contains only vapors of the three hydrocarbons.

(a) Show that the container is currently safe, using Raoult’s law and the Cox chart (Figure 6.1-4) in your calculations.

(b) Obtain a rough estimate of the temperature above which the maximum allowable pressure would be exceeded. Comment on the suitability of the container to store the given mixture.