Explain latent heat and specific latent heat
Answers
Answer:
Explanation:
Latent heat is defined as the heat or energy that is absorbed or released during a phase change of a substance. It could either be from a gas to a liquid or liquid to solid and vice versa. Latent heat is related to a heat property called enthalpy.
However, an important point that we should consider regarding latent heat is that the temperature of the substance remains constant. As far as the mechanism is concerned, latent heat is the work that is needed to overcome the attractive forces that hold molecules and atoms together in a substance.
Let’s take an example. Suppose a solid substance is changing to a liquid, it needs to absorb energy to push the molecules into a wider, more fluid volume. Similarly, when a substance changes from a gas phase to a liquid, their density levels also need to go from lower to a higher level wherein the substance then needs to release or lose energy so that the molecules come closer together. In essence, this energy that is required by a substance to either freeze, melt or boil is said to be latent heat.
Latent Heat Graph
Early Developments of the Concept
English scientific expert Joseph Black presented the idea of latent heat somewhere close to the long periods of 1750 and 1762. Scotch bourbon producers had employed Black to decide the best blend of fuel and water for refining and to examine changes in volume and weight at a steady temperature. Dark applied calorimetry for his investigation and recorded latent heat esteems.
English physicist James Prescott Joule portrayed latent heat as a type of potential vitality. Joule accepted the vitality relied upon the specific design of particles in a substance. Actually, it is the direction of particles inside an atom, their substance holding, and their extremity that influence latent heat.
Types of Latent Heat Transfer
Lets us discuss some the different types of latent heat that can occur.
Latent Heat of Fusion
Latent heat of fusion is the heat consumed or discharged when matter melts, changing stage from strong to fluid-structure at a consistent temperature.
The ‘enthalpy’ of fusion is a latent heat, in light of the fact that during softening the heat vitality expected to change the substance from strong to fluid at air pressure is latent heat of fusion, as the temperature stays steady during the procedure. The latent heat of fusion is the enthalpy change of any measure of substance when it dissolves.
At the point when the heat of fusion is referenced to a unit of mass, it is typically called the specific heat of fusion, while the molar heat of fusion alludes to the enthalpy change per measure of substance in moles.
Answer:
Specific heat:
energy required to change a unit mass of a material by 1°C.
Units: energy per unit mass per degree.
Latent heat =
energy required to change the state (gas, liquid, solid) of a unit mass of material.
Units: energy per unit mass.
Each substance has two specific latent heats:
latent heat of fusion (the amount of energy needed to freeze or melt the substance at its melting point)
latent heat of vaporisation (the amount of energy needed to evaporate or condense the substance at its boiling point)
It usually takes more energy to boil a substance than to melt it, so the latent heat of vaporisation for a substance is usually greater than its latent heat of fusion.