Heat of Fusion Calculator Formula
Understand the math behind the heat of fusion calculator. Each variable explained with a worked example.
Formulas Used
Heat Energy Required
heat = mass * latent_heatHeat Energy (kJ)
heat_kj = mass * latent_heat / 1000Variables
| Variable | Description | Default |
|---|---|---|
mass | Mass(kg) | 1 |
latent_heat | Latent Heat of Fusion(J/kg) | 334000 |
How It Works
Heat of Fusion
The heat of fusion is the energy absorbed during melting at constant temperature.
Formula
Q = m * L_f
where L_f is the specific latent heat of fusion. For water/ice, L_f = 334,000 J/kg = 334 kJ/kg.
Worked Example
Melting 1 kg of ice at 0°C.
mass = 1latent_heat = 334000
- 01Q = m * Lf
- 02Q = 1 * 334000
- 03Q = 334,000 J = 334 kJ
Frequently Asked Questions
Does temperature change during melting?
No. During a phase change, all added energy goes into breaking intermolecular bonds, not raising temperature.
What is the heat of fusion for water?
334 kJ/kg (334,000 J/kg or about 80 cal/g). This is why ice is so effective at cooling drinks.
Is freezing the reverse of melting?
Yes. The same amount of energy released during freezing equals the energy absorbed during melting.
Ready to run the numbers?
Open Heat of Fusion Calculator