Latent Heat Calculator
Solve for Fusion, Vaporization, and Total Heating Curve energy.
| Material | Melting Pt (°C) | L_f Fusion (J/kg) | Boiling Pt (°C) | L_v Vapor (J/kg) |
|---|---|---|---|---|
| Water | 0 | 3.34e+5 (334,000) | 100 | 2.26e+6 (2,260,000) |
| Ethanol | -114 | 1.09e+5 (109,000) | 78 | 8.38e+5 (838,000) |
| Mercury | -39 | 1.14e+4 (11,400) | 357 | 2.96e+5 (296,000) |
| Lead | 327 | 2.30e+4 (23,000) | 1750 | 8.58e+5 (858,000) |
| Silver | 962 | 1.11e+5 (111,000) | 2162 | 2.36e+6 (2,360,000) |
| Gold | 1064 | 6.30e+4 (63,000) | 2856 | 1.64e+6 (1,640,000) |
| Copper | 1085 | 2.07e+5 (207,000) | 2562 | 4.73e+6 (4,730,000) |
| Tungsten | 3422 | 1.34e+5 (134,000) | 5555 | 4.09e+6 (4,090,000) |
| Oxygen | -219 | 1.39e+4 (13,900) | -183 | 2.13e+5 (213,000) |
| Nitrogen | -210 | 2.57e+4 (25,700) | -196 | 2.00e+5 (200,000) |
| Aluminum | 660 | 3.90e+5 (390,000) | 2519 | 1.09e+7 (10,900,000) |
The Energy of Change.
Why does boiling water strictly stay at 100°C? Because all the energy is going "undercover" as Latent Heat.
The Heating Curve
If you heat ice from -20°C to steam at 120°C, it doesn't warm up in a straight line. It follows a "staircase" pattern.
The "Bond Breaker"
Imagine a crowded dance floor (Solid). To turn it into a free-flowing mosh pit (Liquid), you need energy to break the dancers apart.
Solid → Liquid
Molecules loosen from their fixed grid. Requires moderate energy ($L_f$).
Liquid → Gas
Molecules completely separate and fly apart. Requires HUGE energy ($L_v$).
Q = m · L
Simple formula, massive implications. Used ONLY during the flat parts of the heating curve.
Frequently Asked Questions
What is Latent Heat?
Latent Heat is the 'hidden' thermal energy absorbed or released during a phase change (like melting or boiling) at a constant temperature. It is called 'latent' because it doesn't show up on a thermometer.
What is the difference between Fusion and Vaporization?
Fusion ($L_f$) is the energy change between Solid and Liquid (melting/freezing). Vaporization ($L_v$) is the energy change between Liquid and Gas (boiling/condensing). Vaporization usually requires much more energy because you are completely separating the molecules.
Why does the temperature stay constant during melting?
During a phase change, all the supplied heat energy is used to break the intermolecular bonds holding the substance together, rather than increasing the kinetic energy (speed) of the molecules. Since temperature is a measure of kinetic energy, the temperature doesn't rise until the phase change is complete.
What is the Latent Heat of Water?
For Fusion (melting ice), it is $334,000 \text{ J/kg}$. For Vaporization (boiling water), it is a massive $2,260,000 \text{ J/kg}$. This helps explain why steam is so dangerous.
Why are steam burns worse than water burns?
Steam at 100°C has significantly more internal energy than water at 100°C. When steam hits your skin, it releases that massive Latent Heat of Vaporization ($2.26 \text{ MJ/kg}$) just to turn back into liquid water, before it even starts cooling down.
What is the formula for Latent Heat?
The formula is $Q = m \times L$, where $Q$ is Heat Energy (Joules), $m$ is Mass (kg), and $L$ is Specific Latent Heat (J/kg).
Does air have latent heat?
Yes, when components of air (like Nitrogen and Oxygen) change phase. For example, Liquid Nitrogen boils at -196°C and absorbs latent heat to turn into gas.
What is a Heating Curve?
A heating curve is a graph of Temperature vs. Time (or Energy). It looks like a staircase. The flat 'plateaus' are the phase changes (melting/boiling) where latent heat is absorbed. The sloped sections are where the substance is warming up in a specific state.
How do I calculate total energy from Ice to Steam?
You must sum up 5 steps: (1) Heat Ice to 0°C, (2) Melt Ice ($Q=mL_f$), (3) Heat Water to 100°C, (4) Boil Water ($Q=mL_v$), (5) Heat Steam. Our 'Heating Curve' calculator does this automatically!
Can Latent Heat be negative?
Energy is released (negative Q relative to the substance) when freezing or condensing. Energy is absorbed (positive Q) when melting or boiling. The value of $L$ is always positive, but the direction of heat flow depends on the process.