Which among the following are true for an irreversible isothermal expansion of an ideal gas? (i) $W=-Q$ (ii)…
Which among the following are true for an irreversible isothermal expansion of an ideal gas?
(i) $W=-Q$
(ii) $\Delta U=0$
(iii) $\Delta H \neq 0$
(iv) $\Delta T=0$
(i), (ii) and (iii)
(i), (ii) and (iv)
(ii), (iii) and (iv)
(i), (ii), (iii) and (iv)
Solution
In case of isothermal irreversible expansion, the gas is allowed to expand slowly, its temperature tends to fall but some of heat from surrounding is conducted to gas, keeping temperature constant $(\Delta T=0)$. Internal energy is directly proportional to $\Delta T$.
$
\begin{array}{ll}
\therefore & \Delta U=0, \Delta H=0 \Rightarrow \Delta U=Q+W \\
\therefore & W=-Q
\end{array}
$