1. The problem statement, all variables and given/known data A welder using a tank of volume 7.50×10−2 m^3 fills it with oxygen (with a molar mass of 32.0 g/mol) at a gauge pressure of 3.00×105 Pa and temperature of 37.1 C. The tank has a small leak, and in time some of the oxygen leaks out. On a day when the temperature is 23.4 C, the gauge pressure of the oxygen in the tank is 1.85×105 Pa. 2. Relevant equations Find the initial mass of oxygen. Find the mass of oxygen that has leaked out. 3. The attempt at a solution ???