How much work is done by an ideal gas in expanding isothermally from an initial volume of $3.00$ liters at $20.0$ atm to a final volume of $24.0$ liters?
For an isothermal expansion by an ideal gas,
$$
\begin{aligned}
\Delta W &=P_{1} V_{1} \ln \left(\frac{V_{2}}{V_{1}}\right) \\
&=\left(20.0 \times 1.01 \times 10^{5} \mathrm{~N} / \mathrm{m}^{2}\right)\left(3.00 \times 10^{-3} \mathrm{~m}^{3}\right) \ln \left(\frac{24.0}{3.00}\right)=12.6 \mathrm{~kJ}
\end{aligned}
$$