Skip to main content
heat of fusion

heat of fusion

6.3
The amount of heat needed to change one kilogram of solid to liquid at its melting point without changing temperature
  • noun
  • /hiːt əv ˈfjuːʒən/
  • Specialized
translation icon : calor de fusión
  • Understanding the heat of fusion helps explain why melting ice takes time even when the temperature remains constant.

Examples

  • The heat of vaporization and the heat of fusion are two very big numbers multiplied by all that ice.

    Blog text (28)
  • The heat of fusion is the amount of heat needed to turn ice into water at 0 degrees Celsius.

  • When ice melts, it absorbs energy known as the heat of fusion without increasing in temperature.

Antonyms

6.5

Amount of energy given off for each kilogram when a liquid becomes solid, for example when water freezes

Surface Forms

Morphology

heat + of + fusion

The phrase literally combines 'heat' + 'of' + 'fusion', so at a general level a learner can guess it refers to the heat associated with a fusion process (i.e., heat required for fusion/melting). However, the precise technical sense (that 'fusion' here means melting rather than nuclear fusion, and that it denotes the heat per unit mass required at the melting point without temperature change) is specialized and not fully predictable for a B1 learner, so comprehension is only partial without domain knowledge.

Etymology

Heat of fusion uses heat and fusion to describe the amount of heat needed to change a solid into a liquid at its melting point. Imagine an ice cube at 0°C: the ice stays the same temperature while the added heat is used to pull the solid apart so it becomes water, so heat of fusion means the heat needed to 'melt' something.