Question

how could latent heat be explained from the graph ? explain in detail

Answer 1

Latent heat, energy absorbed or released by a substance during a change in its physical state (phase) that occurs without changing itstemperature. The latent heat associated with melting a solid orfreezing a liquid is called the heat of fusion; that associated with vaporizing a liquid or a solid or condensing a vapour is called theheat of vaporization. The latent heat is normally expressed as the amount of heat (in units of joules or calories) per mole or unit mass of the substance undergoing a change of state.

For example, when a pot of water is kept boiling, the temperature remains at 100 °C (212 °F) until the last drop evaporates, because all the heat being added to the liquid is absorbed as latent heat of vaporization and carried away by the escaping vapour molecules. Similarly, while ice melts, it remains at 0 °C (32 °F), and the liquid water that is formed with the latent heat of fusion is also at 0 °C. The heat of fusion for water at 0 °C is approximately 334 joules (79.7 calories) per gram, and the heat of vaporization at 100 °C is about 2,230 joules (533 calories) per gram. Because the heat of vaporization is so large, steam carries a great deal of thermal energy that is released when it condenses, making water an excellent working fluid for heat engines.

Answer 2

In order to initiate a phase change and complete it, some energy in the form of heat is required. this heat is called latent heat . thus all the energy supplied during this phase will be utilized only for phase change process and not for increasing the temperature.. thus during the release of latent heat the temperature remains constant.