A 0.50 kg block of ice at 0 C melts completely into water at 0 C. The latent heat of fusion of ice is 3.34 x 10^5 J/kg. (a) How much heat is absorbed? (b) Why doesn't the temperature rise during melting? Solution: (a) Q = m L = (0.50)(3.34 x 10^5) = 1.67 x 10^5 J. (b) The absorbed heat breaks the hydrogen bonds holding the ice crystal together (increasing potential energy) instead of increasing molecular kinetic energy, so the temperature - which measures average kinetic energy - stays at 0 C until all ice has melted.