A sample of argon of mass 6.56 g occupies 18.5 dm at 305 K. (i) Calculate the work done when the gas expands isothermally against a constant external pressure of 7.7 kPa until its volume has increased by 2.5 dm. (ii) Calculate the work that would be done if the same expans.on occurred reversibly. A12 as a compression: using the same gas of the same mass, calculate the work done for a compression at isothermal conditions with the A) same external pressure of 7.7 kPa, when it's volume decreases from 23 dm to a volume of 2.0 dm. B) reversibly.