Mayer S Relation Cp Cv R — the NEET Physics formula with its derivation, variables, validity constraints and worked solver.
Mayer's Relation (Cp - Cv = R) Applies strictly to Ideal Gases. For real gases, the relation is approximate and requires correction terms involving the equation of state. Start with the definition of Enthalpy H = U + PV Differentiate with respect to Temperature T: dH/dT = dU/dT + d(PV)/dT Substitute definitions of heat capacities: C p = dH/dT and C v = dU/dT (for ideal gas) Apply Ideal Gas Law for 1 mole: PV = RT Substitute d(RT)/dT = R into the equation to get C p = C v + R Substance must behave as an Ideal Gas C p > C v Confusing Molar Heat Capacity (C) with Specific Heat Capacity (c). The relation for specific heat is c p - c v = R/M. Assuming this relation holds exactly for liquids or solids (where C p ≈ C v).