## Essential University Physics: Volume 1 (3rd Edition)

Recall, a diatomic gas has 5 degrees of freedom, so its value of $C_v=2.5R$. Thus, we find the difference in the two values of $C_v$. $\Delta C_v = 3R-2.5R = .5R$ Thus, it follows: $n =\frac{10}{.5}=20 \ moles$