Question #44227

An equilibrium mixture of $\ce{F2(g) + Cl2(g) <=> 2ClF(g)}$ ($\Delta H^\circ = -108 \text{ kJ/mol}$) is contained in a thermally insulated cylinder at temperature $T_1$, fitted with a locked, frictionless piston. $2.0 \text{ moles}$ of ideal Argon gas ($\ce{Ar}$) are injected into the cylinder. Immediately after, the piston is unlocked, allowing the gas mixture to undergo adiabatic expansion against a constant external pressure until mechanical equilibrium is reached at a new temperature $T_2$. Let $\Delta T = T_2 - T_1$ and $\Delta n_{\ce{ClF}}$ be the net change in the number of moles of $\ce{ClF}$ from the initial to the final equilibrium state. Which of the following correctly represents $\Delta T$ and $\Delta n_{\ce{ClF}}$?