A welder using a tank of volume 0.0750 m3 fills it with oxygen 1molar mass 32.0 g>mol2 at a gauge pressure of 3.00 * 105 Pa and temperature of 37.0C. The tank has a small leak, and in time some of the oxygen leaks out. On a day when the temperature is 22.0C, the gauge pressure of the oxygen in the tank is 1.80 * 105 Pa. Find (a) the initial mass of oxygen and (b) the mass of oxygen that has leaked out.