Th e heat capacity of air is much smaller than that of water, and relatively modest amounts of heat are needed to change its temperature. th is is one of the reasons why desert regions, although very hot during the day, are bitterly cold at night. th e heat capacity of air at room temperature and pressure is approximately 21 j k−1 mol−1. how much energy is required to raise the temperature of a room of dimensions 5.5 m × 6.5 m × 3.0 m by 10°c? if losses are neglected, how long will it take a heater rated at 1.5 kw to achieve that increase given that 1 w = 1 j s−1?