A mixture consisting of 1-mol-% ethane, 5-mol-% propane. 44-mol-% n-butane, and 50-mol-% isobutanc is brought to a

Question:

A mixture consisting of 1-mol-% ethane, 5-mol-% propane. 44-mol-% n-butane, and 50-mol-% isobutanc is brought to a condition of 70(°F) at pressure P. If the molar fraction of the system that is vapor is 0.2, what is pressure P. and what are the compositions of the vapor and liquid phases?