Reactions in which heat is given out along with the products are called exothermic reactions.
For example: Burning of methane gas releases a large amount of energy. Hence it is anexothermic reaction.
CH4(g) + 2O2(g) → CO2(g) + 2H2O (g)
Reactions that absorb energy or require energy in order to proceed are calledendothermic reactions.
For example: When ammonium chloride is dissolved in water in a test tube, the test tube becomes cold. Thus the reaction is an example of endothermic reaction.
