One mole of argon gas inside a cylinder fitted with a piston is made to expand very slowly in good thermal contact with its surroundings. During this expansion the volume was doubled and the temperature was constant. The same expansion is performed very rapidly with the cylinder being thermal isolated. The conditions were controlled such that again the volume doubled and the temperature remained constant. Compare the pressure before and after expansion in the two cases
The first process will follow Boyle's Law, such that PV = constant.
Or P1V1 = P2V2
Now, V2 becomes twice of V1, therefore, P1V1 = P2*2V1 or P2 = ...
Calculations to find the pressure of a mole of argon gas which is given more volume at a constant temperature are given.