This uses something called the combined gas law. The combined gas law is as follows: (P1*V1/T1) = (P2*V2/T2) According to question 2, you are given the following values initially: P1 = 680 mm Hg * (1 atm/760 mm Hg) = 0.895 atm V1 = 20.0 L T1 = 293 K STP or standard temperature and pressure implies that the other values we know are: P2 = 1 atm T2 = 273 K Our unknown is V2 If we plug in our known values into the combined gas law: (P1*V1/T1) = (P2*V2/T2) (0.895 atm * 20.0 L)/293K = (1 atm * X liters)/273 K 0.0611 L*atm/K = (1 atm * X liters)/273 K 16.7 L = X liters Therefore, the volume occupied at STP is 16.7 liters This makes sense because the gas would occupy a smaller volume at a lower temperature, since the gas would have a lower average kinetic energy.
