The energy released during the burning of coal, oil is called heat energy. Along with heat energy, light energy is also given out. This is known as combustion reactions.
Combustion takes places in hydrocarbons when they react with the oxygen to produce carbon dioxide and water. A combustion reaction is an example of an exothermic reaction.
Following is the general form of a combustion reaction:
|Hydrocarbon + Oxygen → Carbon dioxide + Water|
Heat energy is defined as the form of energy transfer. Heat is different from temperature, that is heat refers to the transfer of energy between two systems while the temperature is the measure of energy.