The relation between the two molar specific heats of an ideal gas is
- A. Cp minus Cv equals R
- B. Cp plus Cv equals R
- C. Cp times Cv equals R
- D. Cp equals Cv
Explanation
Mayer's relation follows directly from the first law applied to a constant pressure heating, where the extra heat needed is the work of expansion, which for one mole and a one kelvin rise is R. The ratio Cp over Cv, written gamma, is about 1.67 for a monatomic gas and 1.4 for a diatomic one. Gamma governs the speed of sound and adiabatic changes.