The maximum high temperature molar heat capacity at constant volume to be expected for acetylene whi — Thermodynamics and Thermochemistry Chemistry Question

💡 Solution & Explanation

Acetylene ($\text{C}_2\text{H}_2$) has $N = 4$ atoms. For a linear molecule, degrees of freedom are: 3 translational, 2 rotational, and $3N - 5 = 7$ vibrational. At high temperature, equipartition yields $C_v = (3/2)R + (2/2)R + 7R = 9.5R$. With $R \approx 2 \text{ cal/K-mol}$, maximum $C_v \approx 9.5 \times 2 = 19 \text{ cal/deg-mole}$.