What characteristic of a solid’s molecular structure leads to a molar specific heat capacity of approximately 3R ?
**Zeroth law of thermodynamics** if two systems A and B each in thermal equilibrium with third C, then A and B in equilibrium with each other, defines temperature as property that is same for systems in thermal equilibrium, basis for thermometer, temperature scale, thermal equilibrium means no net heat flow, same temperature. In solids, each atom vibrates with 3 degrees of freedom, contributing 3 k_B T (kinetic and potential) per atom. For a mole, this totals 3 R T , so C = (Δ U)/(Δ T) = 3R , due to vibrational motion. Using first law ΔU = Q - W, W = ∫ P
Ref: NCERT > Physics Book > Thermodynamics > Zeroth Law Thermal Equilibrium and Quasi-static