[calvinuk]

An ideal gas occupies a volume of 2.5 dm3 at a pressure of 0.3 MPa. If the gas is compressed isothermally by a constant external pressure, Pext, so that the final volume is 0.5 dm3, what is the smallest value that the external pressure can have? [2 marks]

How much work has been done on the gas? [4 marks]


I can do the first part easy enough, just the question about work i'm struggling with. I don't really know how to work it out. If anyone could point me in the right direction that would be great.

[Bradshaw]

Work done expanding or compressing a gas is pdV. Substitute in p=NkT/V (from the ideal gas law) and integrate from the initial volume to the final volume.