How the Phase Change Calculator Works
The Phase Change Calculator calculates the heat energy required to change a substance from one phase to another. Common examples include melting ice into water or vaporizing water into steam.
During a phase change, temperature stays constant while added energy is used to rearrange molecules. This hidden energy is called latent heat.
Phase Change Formula
The calculator uses:
where Q is heat energy, m is mass, and L is the specific latent heat.
Melting and Vaporization
| Phase change | Description | Energy sign |
|---|---|---|
| Melting | Solid to liquid | Energy absorbed |
| Vaporization | Liquid to gas | Energy absorbed |
| Freezing | Liquid to solid | Energy released |
| Condensation | Gas to liquid | Energy released |
Typical Latent Heat Values
These values are approximate reference values. Actual values can vary with temperature, pressure, and purity.
| Substance | Melting L, J/kg | Vaporization L, J/kg |
|---|---|---|
| Water | 334,000 | 2,260,000 |
| Ethanol | 108,000 | 840,000 |
| Iron | 247,000 | 6,290,000 |
| Aluminum | 397,000 | 10,500,000 |
| Gold | 64,500 | 1,580,000 |
| Lead | 23,000 | 871,000 |
| Silver | 105,000 | 2,330,000 |
| Copper | 206,000 | 4,800,000 |
| Mercury | 11,800 | 296,000 |
| Methanol | 110,000 | 1,100,000 |
Example Calculation
To melt 2 kg of ice at its melting point:
m = 2 kg L = 334,000 J/kg
Then:
Important Limitation
Frequently Asked Questions
What is latent heat?
Latent heat is the energy required to change a substance’s phase without changing its temperature.
Why does temperature stay constant during phase change?
Energy goes into changing molecular arrangement instead of increasing particle kinetic energy.
Why does vaporization usually require more energy than melting?
Vaporization separates molecules much more completely than melting, so it typically requires more energy.
Can I enter a custom latent heat value?
Yes. Select custom latent heat and enter the value in J/kg.