Changes of state and specific latent heat

• If a change of state happens:

  the energy needed for a substance to change state is called latent heat. When a change of state occurs, the energy supplied changes the energy stored (internal energy) but not the temperature
• The specific latent heat of a substance is the amount of energy required to change the state of one kilogram of the substance with no change in temperature
• Equation of specific latent heat

  • Energy for a change of state = mass x specific latent heat

  energy in J, mass in kg, specific Latent heat in j/kg
• • Specific latent heat of fusion - change of state from solid to liquid
  • specific latent heat of vaporisation - change of state from liquid to vapour