One mole of an ideal gas undergoes a reversible process in which the entropy of the gas changes with — Thermodynamics and Thermochemistry Chemistry Question
Question
One mole of an ideal gas undergoes a reversible process in which the entropy of the gas changes with absolute temperature $T$ as: $S = aT + C_{v,m} \ln T$, where $a$ is a positive constant. If $T = T_o$ at $V = V_o$ the volume dependence of the gas on temperature in this process is
💡 Solution & Explanation
Standard entropy differential is $dS = C_V \frac{dT}{T} + R \frac{dV}{V}$. Differentiating the given function $S(T)$ yields $dS = a dT + C_V \frac{dT}{T}$. Equating them leaves $a dT = R \frac{dV}{V}$. Integrating from initial state ($T_o, V_o$) to ($T, V$) results in $a(T - T_o) = R \ln\left(\frac{V}{V_o}\right) \implies T = T_o + \frac{R}{a} \ln\left(\frac{V}{V_o}\right)$.