A plot of temperature versus time, showing the amount of energy a substance has absorbed with increasing temperature
A heating curve is a plot or graph wherein a substance is subjected to increasing temperature against time to measure the amount of energy it absorbs and changes state with increasing temperature.
The heating curve usually involves a system in a closed container in order to isolate it from its environment and observe how it changes as it is influenced by the heat. When heated, the system absorbs the energy. This, then, causes the system to change its state. For instance, a substance in a solid state will change into another state, e.g. liquid state, as it absorbs energy. Nevertheless, a plateau is reached when the substance reaches melting point, i.e. changing from solid to liquid. When this happens the temperature does not change due to heat of fusion. With further increase in temperature, the substance that turned to liquid will turn into gas as it absorbs energy. When the substance reaches boiling point, the temperature does not change due to heat of vaporization. The rate of temperature increase is dependent upon the heat capacity of the phase in the system.1
1 The Heating Curve. Retrieved from ://www.science.uwaterloo.ca/~cchieh/cact/c123/heating.html.