What does 'latent heat' refer to in thermodynamics?

Latent heat is a crucial concept in thermodynamics that refers to the amount of heat energy that is absorbed or released by a substance during a phase change without a change in temperature. This can occur during transitions such as melting (solid to liquid) or boiling (liquid to gas). During these processes, the temperature of the substance remains constant while the energy is used to overcome intermolecular forces rather than to change its temperature.

This means that when a substance changes from one state to another, such as ice melting into water or water evaporating into steam, it is absorbing or releasing energy in the form of latent heat. This energy is necessary for the phase change to occur and is a key factor in many thermodynamic processes.

The other options involve forms of heat transfer or energy changes that do not represent the concept of latent heat. For instance, heat absorbed during mechanical work refers to energy transfer due to work input rather than a phase change. Heat released during combustion is associated with chemical reactions rather than phase transitions. Heat loss during thermal conduction involves heat transfer from a hotter object to a cooler one through direct contact, which again does not involve a change in phase. Therefore, the definition of latent heat distinctly applies to the process of heat transfer related specifically to