Latent heat is the energy a substance absorbs to change state at constant temperature, Q = m·L. Drag the sliders below to set the heater power, sample mass and starting temperature, and watch the heating curve flatten at melting and boiling.
Your ice sits at a chilly starting temperature, the heater pours in energy, and the graph climbs steadily. Then, at 0 °C, something strange happens: the line flattens. You are still feeding in the same power, yet the temperature refuses to budge. This flat plateau is melting, and every joule now goes into loosening the rigid bonds that hold solid ice together rather than warming it. The relationship shifts from Q = m·c·ΔT, which lifts temperature, to Q = m·L, which changes state at constant temperature.
Once the last crystal turns to liquid, the slope returns as water heats toward 100 °C. Then the curve stalls a second time for boiling. Notice how much longer this plateau runs: the latent heat of vaporisation dwarfs the latent heat of fusion, because tearing molecules fully apart into steam costs far more energy than merely melting. That is the classic trap this simulation exposes — heating does not always mean a rising thermometer.
Crank the Heater power and the sample marches through each stage sooner, though the plateau heights stay locked at 0 °C and 100 °C. Raise the Sample mass and every stage stretches out, since more matter demands more total energy. Confirm your reading with the latent heat calculator, then try the rest of our interactive physics simulations.
It is the energy absorbed or released when a substance changes state — melting or boiling — at constant temperature, Q = m·L, where L is the specific latent heat. It breaks the bonds between particles rather than raising the temperature.
Because the added heat goes into breaking the bonds of the solid rather than increasing the particles' kinetic energy. The thermometer holds steady until the melting is complete.
The specific latent heat of vaporisation is much larger than that of fusion. Fully separating molecules into a gas takes far more energy than loosening a solid into a liquid, so boiling absorbs more heat.
No. More power reaches each stage sooner, but the plateau temperatures — 0 °C for melting and 100 °C for boiling water at normal pressure — are fixed. More mass lengthens every stage.