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)