What does one mean by exothermic and endothermic reactions? Give examples

What does one mean by exothermic and endothermic reactions? Give examples.

Answer: Exothermic reaction: A reaction in which heat is released is called the exothermic reaction.

Example: Burning of fuel is an example of exothermic reaction. When methane is burnt it gives heat along with carbon dioxide and water.

CH4 (g) + 2O2 (g)⇨ CO2 (g) + 2H2O

Endothermic reaction: A reaction in which heat is absorbed is called endothermic reaction.

Example: When silver chloride is left in the sunlight, it absorbs heat and turns grey because of formation of silver metal.

2AgCl (s) ⇨ 2Ag (s) + Cl2 (g)