Latent Heat of Fusion and Vaporization

Latent heat is the amount of heat energy required to change the state of matter without changing its temperature. There are two types of latent heat: latent heat of fusion and latent heat of vaporization.

Latent Heat of Fusion

Latent heat of fusion is the amount of heat energy required to change a substance from a solid state to a liquid state at its melting point. The heat energy is used to break the intermolecular forces between the molecules of the substance. Once the intermolecular forces are broken, the solid starts to melt and changes its state to a liquid. The formula to calculate the latent heat of fusion is Q = mLf, where Q is the amount of heat energy required, m is the mass of the substance, and Lf is the latent heat of fusion.

Latent Heat of Vaporization

Latent heat of vaporization is the amount of heat energy required to change a substance from a liquid state to a gaseous state at its boiling point. The heat energy is used to break the intermolecular forces between the molecules of the substance. Once the intermolecular forces are broken, the liquid starts to boil and changes its state to a gas. The formula to calculate the latent heat of vaporization is Q = mLv, where Q is the amount of heat energy required, m is the mass of the substance, and Lv is the latent heat of vaporization.

Important Points - Matter in our Surroundings

1. Matter is made up of particles that are in constant motion.
2. The intermolecular forces between the particles determine the state of matter.
3. The state of matter can be changed by changing the temperature or pressure.
4. The melting point and boiling point are the temperatures at which a substance changes its state.
5. Latent heat is the amount of heat energy required to change the state of matter without changing its temperature.
6. Latent heat of fusion is the amount of heat energy required to change a substance from a solid state to a liquid state at its melting point.
7. Latent heat of vaporization is the amount of heat energy required to change a substance from a liquid state to a gaseous state at its boiling point.

The latent heat associated with melting a solid or freezing a liquid is called the heat of fusion.

The latent heat of vapourization is a physical property of substance. It is defined as the heat required to change one mole of liquid at its boiling point under standard atmospheric pressure.