A system containing 10 mol of an ideal gas is maintained at thermal equilibrium (at the same temperature) as its surroundings, at a temperature of 50 °C. It then has 100 kJ of heat transferred to it, which causes it to expand isothermally against a constant pressure of 1 atm. It is then isothermally compressed back to its initial volume. What is its change in enthalpy over the entire process? Express your answer in units of kJ.