Practice question

**Heat capacity** at constant pressure C_p and volume C_v, C_p = C_v + R per mole, for solids Dulong-Petit C_v≈3R≈25 J/mol·K. Specific heat and latent heat govern temperature changes and phase transitions, Q = m c ΔT for heating, Q = m L for melting/boiling at constant T. Δ Q = m s Δ T . m = 0.4 , s = 134.4 , Δ T = 70 - 40 = 30 . Δ Q = 0.4 × 134.4 × 30 = 1612.8 J ≈ 1613 J . Using first law ΔU = Q - W, W = ∫ P dV, isobaric W = P