Latent Heat Formula

Latent heat is energy released or absorbed, by a body during a constant-temperature process, for example a phase change of water from liquid to gas. This is written as:

Sensible heat = (mass of the body) * (specific latent heat)

The equation is

Q= m L

We have:

Q: Latent heat

m: Mass of the body

L: Specific latent heat coefficient of the material

Sensible heat equation Questions:

1) Some solid material of 0.5 Kg with a specific latent of fusion of 334 KJ/Kg change it phase from solid to liquid, what is the latent heat of this piece of material?

Answer: The latent heat is given by the equation:

Q= m L

substituting the value of m, and the specific latent heat

Q= 0.5 Kg * 334 KJ/Kg = 167 KJ = 167000 J

This is the amount of energy released when water is melting at 0 °C.

2) A liquid with an latent heat of 885 KJ/Kg evaporates, its latent heat is of 50 KJ, what is the mass of the liquid?

Answer: The mass is given from the equation of latent heat:

m = Q / L

Then, substituting the value Q, and the specific latent heat,

m = 50 KJ /885 KJ/Kg = 0.056 Kg

m = 56 grams