Temperature of a liquid is raised by heating

This is not some incredible scientific breakthrough, obviously…the temperature of a liquid is raised by heating…yes indeed. Sciencebase gets a lot of visitors trying to do their science homework, it seems. Often they’re trying to find out the effects of adding salt to the boiling point of water, that kind of thing.

latent-heat-is-on

Today, one person (don’t know if they’re a student or not) just hit the site with this phrase: “the temperature of a liquid is raised by heating”. They’re right, of course. Although there is a caveat. If you boil a liquid or melt a solid then there is the issue of latent heat.

Latent heat is the energy released or absorbed by a body or a thermodynamic system during a constant-temperature process (i.e. it doesn’t get hotter). A typical example is a change of state of matter, meaning a phase transition such as the melting of ice or the boiling of water. Scottish chemist Joseph Black coined the term in the 18th Century and used it in the context of calorimetry when referring to the heat transferred that caused a change of volume while the thermodynamic system was held at constant temperature.

The counterpart to latent heat, which we usually just think of as heat is an energy referred to as sensible energy or heat which does cause processes to change the temperature of a system.