Question

Write the expression for the work done by 1 mole of gas into an evacuated vessel

Answer 1

Explanation:

Let the piston of area of cross-section A move through a small distance dx so that the gas expands by a small amount dV. As the expansion is small, the pressure of the gas remains , practically, constant, say P.

Then the force acting on the piston, F = P×A

and small work done by the gas,

dW = F dx

= PA dx

dW = P dV [Since, A dx = dV]