2 moles of an ideal monoatomic gas undergoes reversible expansion from (4 L, 400 K) to 8 L such that — Thermodynamics and Thermochemistry Chemistry Question

💡 Solution & Explanation

Using the relation $T_1 V_1^2 = T_2 V_2^2$, we substitute initial conditions $400 \times 4^2 = T_2 \times 8^2 \implies 400 \times 16 = 64 T_2 \implies T_2 = 100 \text{ K}$. The temperature change $\Delta T = 100 - 400 = -300 \text{ K}$. The enthalpy change $\Delta H = n C_p \Delta T = 2 \times \frac{5}{2} R \times (-300) = -1500 R$.