Calculate the work associated with the expansion of a gas from 46 L to 64 L at a constant external presure of 15 atm.

Solution:

The work required to expand a gas against a exterior presure is: \begin{equation} w=-P\Delta V \end{equation} In this case: $\Delta V=64-46=18\; L$ Hence: \begin{equation} w=-15\;atm\cdot18\;L=-270\;atmL \end{equation} Works is negative, since the gas expanding.