Final answer:
To calculate the work done during an adiabatic expansion, the specific heat at constant volume and the mass of steam must be known. Without this data, it's not possible to provide an exact numerical answer for the work done per unit mass.
Step-by-step explanation:
The question involves determining the work done by steam undergoing an adiabatic expansion in a piston-cylinder assembly. In an adiabatic process, there is no exchange of heat with the surroundings (Q=0). The work done by the gas is equal to the change in its internal energy since the first law of thermodynamics can be written as ΔU = Q - W.
For an adiabatic expansion of an ideal gas, we can use the formula W = Cv(T1 - T2), where W is the work done, Cv is the specific heat at constant volume, and T1 and T2 are the initial and final temperatures, respectively. However, we would need more data such as the specific heat at constant volume and the mass or number of moles of steam to calculate the work per unit mass. Since the question doesn't provide such specifics and focuses on steam, which may not behave as an ideal gas, an exact numerical answer cannot be provided without making assumptions.