1. Dry air is 78% N2, 21% O2 and 1% Ar.
(a) What is the molar mass of dry air?
(b) What is the molar mass on a humid day when the water vapor content is 3%?
2. For a certain hot air balloon, the mass of the balloon, harness, basket and payload is 600 kg. The air temperature inside the balloon is 70 "C and that outside it is 18 "C. Estimate the minimum volume of hot air needed if the balloon is to lift off the ground. (The molar mass of air is about 0.029 kg and atmospheric pressure is 1 .013 x 105 Pa.)