The constituent partial pressures of a gas in equilibrium with a liquid solution at 30°C and 1 atm containing 2 lbm SO2/100 lbm H2O are pH2O = 31:6 mm Hg and pSO2 = 176 mm Hg. The balance of the gas is air.

(a) Calculate the partial pressure of air. If you make any assumptions, state what they are.

(b) Suppose the only data available on this system gave pSO2 = 176 mm Hg, but there was no information given on the equilibrium partial pressure of water. Use Raoult's law to estimate a value for this quantity. Assuming that the value given in the problem statement is correct, what percentage error results from using Raoult's law?