This concept covers calorimetry and phase-change energy balance in thermochemistry: when two substances at different temperatures and/or phases are brought into contact, heat flows from the warmer body until thermal equilibrium is reached, and the heat lost by one substance equals the heat gained by the other. Quantifying this requires two distinct heat-transfer relations: q = mcΔT for temperature changes within a single phase (using a phase-specific specific heat capacity, e.g. different values for solid and liquid water), and q = mL for phase transitions at constant temperature (using the latent heat of fusion, the energy absorbed or released during melting/freezing without a temperature change). Solving for an unknown mass in such a system requires setting the total heat absorbed (sum of a sensible-heat term and a latent-heat term) equal to the total heat released by the cooling substance, reflecting conservation of energy in a closed thermal system.
This concept covers calorimetry and phase-change energy balance in thermochemistry: when two substances at different temperatures and/or phases are brought into contact, heat flows from the warmer bo…