1. Calculate the molar volume of Ar at 500K and 60 atm according to

(i) the ideal gas equation;

(ii) the van der Waals equation, given a = 3.640 L2 atm mol-2 and b= 0.004267 L mol-1

2. Consider a 10.0 L SCUBA diving tank containing 20.0 mol O2 at 20.0oC. Use the van der Waals equation (a = 1.378 L2 atm mol-2; b = 0.03183 L mol-1) to calculate the:

(i) pressure, p

(ii) compressibility, Z

Comment on the relative importance of attractive and repulsive forces between molecules in determining the behaviour of the gas.