The constant-volume heat capacity of a gas can be measured by observing the decrease in temperature when it expands adiabatically and reversibly. if a decrease in pressure is also measured, we can use it to infer the value of γ (the ratio of heat capacities, cp/cv) and hence, by combining the two values, deduce the constant pressure heat capacity. a fluorocarbon gas was allowed to expand reversibly and adiabatically to twice its volume; as a result, the temperature fell from 298.15 k to 248.44 k and its pressure fell from 1522.2 torr to 613.85 torr. evaluate cp.