Latent Heat Calculator (Q = mL)
Latent Heat Calculator (Q = mL)
Latent heat is the energy absorbed or released during a phase change (melting, freezing, boiling, or condensing) without any change in temperature. Choose which quantity you want to solve for, enter the other two known values, and this calculator computes the missing one.
Latent heat comes in two distinct flavors — fusion (melting or freezing) and vaporization (boiling or condensing) — and for water specifically, the latent heat of vaporization (about 2,260,000 J/kg) is roughly 6.8 times larger than its latent heat of fusion, which is the physical reason steam burns are so much more severe than an equivalent splash of boiling water: converting water to steam absorbs (and later releases) dramatically more energy than melting ice does. This "no temperature change during the phase change itself" property is also why a glass of ice water stays at a steady 0°C while the ice is melting, rather than warming up gradually the whole time.
- The core formula is Q = m × L, so melting 1 kg of ice (latent heat of fusion 334,000 J/kg) takes 1 × 334,000 = 334,000 J.
- Latent heat comes in two flavors: fusion (melting/freezing) and vaporization (boiling/condensing) - water's latent heat of vaporization (about 2,260,000 J/kg) is roughly 6.8 times its latent heat of fusion, which is why boiling water takes so much more energy than just melting ice.
- This is why ice at 0°C stays at 0°C while it melts - all the added heat goes into breaking molecular bonds (the phase change), not raising the temperature, until melting is complete.
How do I calculate the heat needed for a phase change?
Multiply the mass by the latent heat of the substance: Q = m × L.
How much energy does it take to melt 1 kg of ice?
Q = 1 × 334,000 = 334,000 J, using ice's latent heat of fusion.
Latent Heat Calculator (Q = mL)
Latent heat is the energy absorbed or released during a phase change (melting, freezing, boiling, or condensing) without any change in temperature. Choose which quantity you want to solve for, enter the other two known values, and this calculator computes the missing one.
Latent heat comes in two distinct flavors — fusion (melting or freezing) and vaporization (boiling or condensing) — and for water specifically, the latent heat of vaporization (about 2,260,000 J/kg) is roughly 6.8 times larger than its latent heat of fusion, which is the physical reason steam burns are so much more severe than an equivalent splash of boiling water: converting water to steam absorbs (and later releases) dramatically more energy than melting ice does. This "no temperature change during the phase change itself" property is also why a glass of ice water stays at a steady 0°C while the ice is melting, rather than warming up gradually the whole time.
- The core formula is Q = m × L, so melting 1 kg of ice (latent heat of fusion 334,000 J/kg) takes 1 × 334,000 = 334,000 J.
- Latent heat comes in two flavors: fusion (melting/freezing) and vaporization (boiling/condensing) - water's latent heat of vaporization (about 2,260,000 J/kg) is roughly 6.8 times its latent heat of fusion, which is why boiling water takes so much more energy than just melting ice.
- This is why ice at 0°C stays at 0°C while it melts - all the added heat goes into breaking molecular bonds (the phase change), not raising the temperature, until melting is complete.
How do I calculate the heat needed for a phase change?
Multiply the mass by the latent heat of the substance: Q = m × L.
How much energy does it take to melt 1 kg of ice?
Q = 1 × 334,000 = 334,000 J, using ice's latent heat of fusion.