One mole of ideal monatomic gas is confined in a cylinder by a piston and is maintained at a con- stant temperature To by thermal contact with a heat reservoir. The gas slowly expands from Vị to V2 while being held at the same temperature To. Why does the internal energy of the gas not change? Calculate the work done by the gas and the heat flow into the gas.

One mole of ideal monatomic gas is confined in a cylinder by a piston and is maintained at a con- stant temperature To by thermal contact with a heat reservoir. The gas slowly expands from Vị to V2 while being held at the same temperature To. Why does the internal energy of the gas not change? Calculate the work done by the gas and the heat flow into the gas.