An ideal gas is in contact with a heat reservoir so that it remains at a constant temperature of 300.0 K. The gas is compressed from 24.0 L to 14.0 L. The mechanical device that operates the piston to compress the gas expends 5.00 kJ of energy. How much heat flows between from the heat reservoir to the gas?
A) −3.0 kJ
B) −5.1 kJ
C) −2.0 kJ
D) −5.0 kJ

Question

Quizplus · Accepted Answer

Since the temperature is constant, the change in internal energy is zero. Therefore, the heat flow Q equals the work done on the gas W (by the mechanical device). We know that W = -5.00 kJ (since the piston did work on the gas), so Q = -5.00 kJ. The negative sign indicates that heat is flowing out of the gas (since the gas is being compressed) and thus the answer is (D) -5.0 kJ.

An Ideal Gas Is in Contact with a Heat Reservoir