What is the term for the amount of heat energy that must be removed to change 1 lb of solid into 1 lb of liquid?

The correct term for the amount of heat energy that must be removed to change 1 lb of solid into 1 lb of liquid is the latent heat of fusion. This process occurs when a solid substance, such as ice, absorbs heat energy to break the intermolecular bonds that hold its structure together, allowing it to transition into a liquid state. The term “latent heat” refers to the heat absorbed or released during a phase change without changing temperature, and "fusion" specifically pertains to the melting of a solid.

While the term "latent heat of melting" may seem appropriate, it is not the standard terminology used in thermodynamics or HVAC discussions. The common and widely recognized term is "latent heat of fusion." This distinction is important in the context of phase change terminology.

Latent heat of vaporization, by contrast, involves the transition from a liquid to a gas, which is a different phase change entirely. Mean temperature differences refer to a concept used in thermodynamics related to heat transfer calculations and does not pertain to phase changes. Understanding these definitions is crucial for accurate communication of thermodynamic processes.