give me 2 examples of endothermic and exothermic reactions.

Reactions in which heat is given out along with the products are called exothermic reactions.

For example 

1) Burning of methane gas releases a large amount of energy. Hence it is an exothermic reaction. 

CH₄ (g) + 2O₂ (g) → CO₂ (g) + 2H₂O (g)

2) Reaction of calcium oxide and water. Calcium oxide reacts vigorously with water to produce calcium hydroxide.

A large amount of heat is also evolved during this process, which increases the temperature of the system.

Reactions that absorb energy or require energy in order to proceed are called endothermic reactions.

For example : 

1) 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. 

2) When barium hydroxide is mixed with ammonium chloride, the two compounds react to form barium chloride, ammonia and water. Also, the reaction system becomes cold and so the reaction is an endothermic reaction. A balanced chemical equation showing the reaction is as follows

 Ba(OH)₂ + 2NH₄Cl → BaCl₂ + 2NH₃ + 2H₂O