What is the primary factor in determining specific latent heat?

The primary factor in determining specific latent heat is the type of material. This is because specific latent heat is defined as the amount of heat energy required to change the state of a unit mass of a substance without changing its temperature. Different materials have unique atomic or molecular structures which influence how much energy is needed to overcome the forces between particles during the phase transition, such as melting or boiling. Therefore, the specific latent heat value is intrinsic to the material itself.

As for the other factors, while the speed of heat transfer can influence how quickly a substance reaches its latent heat point, it does not alter the amount of energy required for the phase change. Similarly, the volume of the material is not a determining factor since specific latent heat is expressed per unit mass and therefore depends on the mass of the substance rather than its total volume. Lastly, the temperature at which a phase change occurs can vary depending on the material and its state, but it is not the primary factor in defining the specific latent heat itself.