Which equation expresses latent heat for a phase change?

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Multiple Choice

Which equation expresses latent heat for a phase change?

Latent heat is the energy involved when a substance changes from one phase to another at a constant temperature. The amount of energy required (or released) during that phase change depends on how much material you have and how much energy is needed to change the phase per unit mass. That’s why the total latent heat is found by multiplying mass by the latent heat per unit mass, L. In symbols, the energy associated with a phase change equals m times L, so Q (or Ethermal) = m L. This directly expresses the idea of latent heat. Other formulas describe heating where the temperature changes (m c ΔT or Q = m ΔT), which isn’t what happens during a phase change. The rearranged form L = Q / m is mathematically equivalent to Q = m L, but the standard way to express latent heat for a phase change is Q = m L.

Latent heat is the energy involved when a substance changes from one phase to another at a constant temperature. The amount of energy required (or released) during that phase change depends on how much material you have and how much energy is needed to change the phase per unit mass. That’s why the total latent heat is found by multiplying mass by the latent heat per unit mass, L. In symbols, the energy associated with a phase change equals m times L, so Q (or Ethermal) = m L. This directly expresses the idea of latent heat.

Other formulas describe heating where the temperature changes (m c ΔT or Q = m ΔT), which isn’t what happens during a phase change. The rearranged form L = Q / m is mathematically equivalent to Q = m L, but the standard way to express latent heat for a phase change is Q = m L.

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