Question

One mole of a gas expands by $3L$ against a constant pressure of $3$ atmosphere. Calculate the work done in L atmosphere.

Answer 1

The work done $\left(W\right)$ when the gas expands at constant pressure $P(=3atm)$ from volume $V_1$ to $V_2$ is given by,
$W=-{\int }_{V_1}^{V_2}Pdv$

$=-P{\int }_{V_1}^{V_2}dv$

$=-P(V_2-V_1)=-P\Delta V$

Where the negative sign indicates work done by the system.

Here $△V=3L$

$W=-P△V=-3\times 3Latm=-9lit.atm$.