• All solids absorb heat as they melt to become liquids.
  • The gain of heat in this endothermic process goes into changing the state rather than changing the temperature.
  • When 1 mol of water at 0°C freezes to ice, 6.01 kJ of heat are released into the surroundings.
  • The molar heat of fusion  of a substance is the heat absorbed by one mole of that substance as it is converted from a solid to a liquid.
  • Since fusion and solidification of a given substance are the exact opposite processes, the numerical value of the molarheat of fusion is the same.
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