In a test of the effects of low temperatures on the gas mixture, a cylinder filled at 20.0°C to 2000 psi (gauge pressure) is cooled slowly and the pressure is monitored. What is the expected pressure at -5.00°C if the gas remains a homogeneous mixture?
(a) 500 psi;

(b) 1500 psi;

(c) 1830 psi;

(d) 1920 psi.

One type of gas mixture used in anesthesiology is a 50%/50% mixture (by volume) of nitrous oxide (N₂O) and oxygen (O₂), which can be premixed and kept in a cylinder for later use. Because these two gases don’t react chemically at or below 2000 psi, at typical room temperatures they form a homogeneous single gas phase, which can be considered an ideal gas. If the temperature drops below -6°C, however, N₂O may begin to condense out of the gas phase. Then any gas removed from the cylinder will initially be nearly pure O₂; as the cylinder empties, the proportion of O₂ will decrease until the gas coming from the cylinder is nearly pure N₂O.