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
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