2.3 Exercise 9

A steel container of mass 135 g contains 24.0 g of ammonia, $\text{NH}_{3}$, which has a molar mass of 17.0 g/mol. The container and gas are in equilibrium at $12.0 °\text{C}$. How much heat has to be removed to reach a temperature of $−20.0 °\text{C}$ ? Ignore the change in volume of the steel and treat the ammonia as an ideal gas with 6 degrees of freedom (3 translational and 3 rotational; at room temperature, the vibrational degree of freedom is inactive.)