How many calories are absorbed by 3 moles of an ideal gas?

Question

expanding isothermally from the initial pressure of 5 atmosphers to the final pressure of 3 atmospheres ,at the temperature of 0 C?

Answer 1

P=nRT/V. Since the expansion is isothermal, the internal energy of the gas is constant, energy absorbed = work done. Work done is given has area under the P-V graph. Integrate the equation to find the area.