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Specific latent heat calculator

GCSEA-level Thermal physics and gases

The energy needed to change the state of a mass of material without changing its temperature.

E = m L

This free calculator is for GCSE and A-level physics. Choose the quantity you want to find, enter the other values with their units, and it shows the working in the layout used in exams, with the answer to the number of significant figures you choose. The values shown are an example. Change them to your own.

Quantity to find

66800 J

Working

  1. Write the equation
    E = m L
  2. Substitute the values
    E = 0.2 × (3.34 × 105)
  3. Calculate
    E = 66800 J
  4. Give the answer to 3 significant figures
    E = 66800 J
    In standard form: 6.68 × 104 J

Worked example

Find E, the energy for a change of state. Given: mass m = 0.200 kg; specific latent heat L = 3.34 × 10⁵ J/kg.

  1. Write the equation
    E = m L
  2. Substitute the values
    E = 0.2 × (3.34 × 105)
  3. Calculate
    E = 66800 J
  4. Give the answer to 3 significant figures
    E = 66800 J
    In standard form: 6.68 × 104 J

Symbols and units

SymbolQuantitySI unit
EEnergy for a change of stateJ
mMasskg
LSpecific latent heatJ/kg

Specific latent heat: rearranged

  • To find energy for a change of state: E = m L
  • To find mass: m = E / L
  • To find specific latent heat: L = E / m

Exam tip

Use the latent heat of fusion for melting and freezing, and of vaporisation for boiling and condensing.

Common questions

What is the formula for specific latent heat?

The equation is E = m L, where E is the energy for a change of state (J); m is the mass (kg); L is the specific latent heat (J/kg).

What units should I use for specific latent heat?

In SI units: energy for a change of state in J, mass in kg, specific latent heat in J/kg. The calculator also accepts common alternatives such as kilometres, grams or minutes, and converts them for you.

How do I rearrange E = m L?

Rearranging gives these forms: to find energy for a change of state: E = m L. to find mass: m = E / L. to find specific latent heat: L = E / m.

Practise specific latent heat questions

Press the button for a question with random numbers. Work it out on paper first, then type your answer.

Related

Read the full explanation on the Specific latent heat formula page. More thermal physics and gases equations: Specific heat capacity, Ideal gas equation, Boyle’s law, Gas equation with molecules, Mean kinetic energy of a gas atom, Stefan–Boltzmann law, Wien’s law. See the full list on the physics equation calculator page.