what is latent heat

Latent heat is the heat energy released or absorbed by a body or a thermodynamic system during a constant-temperature process, usually a first-order phase transition. It is the energy required for an object to change phase, such as melting, boiling, or freezing, without changing its temperature. Latent heat can be understood as hidden energy which is supplied or extracted to change the state of a substance. There are two common forms of latent heat: latent heat of fusion (melting) and latent heat of vaporization (boiling) . The names describe the direction of energy flow when changing from one phase to the next: from solid to liquid, and liquid to gas. Latent heat arises from the work required to overcome the forces that hold together atoms or molecules in a material. The regular structure of a crystalline solid is maintained by forces of attraction among its individual atoms, which oscillate slightly about their average positions in the crystal lattice. The specific latent heat of a substance is the amount of energy needed to change the state of 1 kg of the substance without changing its temperature. It is an intensive property of matter and is measured per unit mass. The formula for specific latent heat is L = Q/m, where L is the specific latent heat, Q is the heat energy, and m is the mass of the substance undergoing a change of state.