Calculate heat of crystallization, mass, or heat of fusion from any two values, with units for J, kJ, cal, kcal, g, kg, and lb, and step-by-step results.
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Heat Of Crystallization Formula
The heat of crystallization is calculated from mass and heat of fusion. The calculator treats heat of crystallization as the magnitude of heat released during crystallization, so the result is shown as a positive amount of energy.
Hc = m * Hf
m = Hc / Hf
Hf = Hc / m
- Hc = heat of crystallization, usually in joules (J) or kilojoules (kJ)
- m = mass of the substance, usually in grams (g)
- Hf = heat of fusion, usually in J/g
The calculator has three functions based on which value you leave blank:
- Calculate heat of crystallization: enter mass and heat of fusion. The calculator multiplies them.
- Calculate mass: enter heat of crystallization and heat of fusion. The calculator divides heat by heat of fusion.
- Calculate heat of fusion: enter heat of crystallization and mass. The calculator divides heat by mass.
Common Heat of Fusion Values
Heat of crystallization has the same magnitude as heat of fusion for the same substance at its melting/freezing point. Actual values can vary slightly with purity and reference conditions.
| Substance | Approx. Heat of Fusion | Meaning for Crystallization |
|---|---|---|
| Water | 333.6 J/g | 1 g of water releases about 333.6 J when it freezes. |
| Ethanol | 108.9 J/g | 1 g releases about 108.9 J when it crystallizes. |
| Aluminum | 397 J/g | 1 g releases about 397 J when it solidifies. |
| Copper | 205 J/g | 1 g releases about 205 J when it solidifies. |
Unit Relationships for Checking Results
| Quantity | Useful Conversion | Note |
|---|---|---|
| Heat | 1 kJ = 1000 J | Use this when converting the final heat result. |
| Heat | 1 cal = 4.184 J | Calories and joules are both energy units. |
| Mass | 1 kg = 1000 g | The base formula uses grams with J/g. |
| Heat of fusion | 1 kJ/kg = 1 J/g | These two units have the same numeric value. |
Example Heat Of Crystallization Calculations
Example 1: Calculate heat of crystallization
You have 250 g of water and use a heat of fusion of 333.6 J/g.
Hc = m * Hf
Hc = 250 * 333.6 = 83400 J
The heat of crystallization is 83,400 J, or 83.4 kJ.
Example 2: Calculate mass
A crystallization process releases 25 kJ of heat. The heat of fusion is 200 J/g.
First convert 25 kJ to joules:
25 kJ = 25000 J
Then solve for mass:
m = Hc / Hf = 25000 / 200 = 125 g
The mass is 125 g.
Heat Of Crystallization Calculator FAQ
Is heat of crystallization the same as heat of fusion?
They have the same magnitude for the same substance at the phase-change temperature, but the direction is different. Heat of fusion is the heat absorbed when a solid melts. Heat of crystallization is the heat released when a liquid becomes a solid. If you use a sign convention, crystallization is often written as negative because heat leaves the substance.
Why do you enter exactly two values?
The formula has three variables: heat of crystallization, mass, and heat of fusion. If you know any two, the third can be calculated. If you enter all three, there is no missing value to solve for. If you enter only one, there is not enough information.
What units should you use?
You can use any supported unit, but the easiest hand calculation is usually joules for heat, grams for mass, and J/g for heat of fusion. In that form, the units cancel cleanly: grams multiplied by J/g gives joules.