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

💡 Solution & Explanation

Acetylene ($C_2H_2$) is a linear molecule. Total degrees of freedom = 3 * N = 3 * 4 = 12. Translation = 3, Rotation = 2, Vibration = 12 - 3 - 2 = 7. At high temperatures, vibrational modes are fully active. $C_{v,m}$ = 1.5 R (trans) + R (rot) + 7 R (vib) = 9.5 R. Since R approx 2 cal/K-mol, $C_{v,m}$ = 9.5 * 2 = 19 cal/K-mol.