Specific heat capacity and latent heat · Grade 11
Different materials need different amounts of energy to warm up: water needs a lot, metals much less. This is their specific heat capacity. When a substance melts or boils, energy is needed to change its state without changing its temperature: this is latent heat.
Key facts
- Energy to change temperature: E = mcΔT (c = specific heat capacity, J/kg °C).
- Water: c = 4,200 J/kg °C, much higher than most substances.
- Energy to change state: E = mL (L = specific latent heat, J/kg).
- Water: L (fusion) = 334,000 J/kg; L (vaporisation) = 2,260,000 J/kg.
- During melting or boiling the temperature stays constant (flat parts of a heating curve).
- When hot and cold mix: energy lost by the hot = energy gained by the cold.