Question

The pressure-volume work for an ideal gas can be calculated by using the expression $W = - \int\limits^{V_{f}}_{V_i} P_{ex} \,dV$. The work can also be calculated from the $PV -$ plot by using the area under the curve within the specified limits. When an ideal gas is compressed $(i)$ reversibly or $(ii)$ irreversibly from volume $V_i$ to $V_f$. Choose the correct option.

• A. $W_{reversible} = W_{irreversible}$
• B. $W_{reversible} > W_{irreversible}$
• C. $W_{reversible} < W_{irreversible}$
• D. $W_{reversible} = W_{irreversible} + P_{ex} \Delta \,V$

Answer 1

Answer: (B)

$W_{reversible} > W_{irreversible}$

Answer 2

In both the curves, work done on the gas is represented by the shaded area and the area under the curve is always more in irreversible compression. Hence, $W_{irreversible} > W_{reversible}$