Question: Identify the type of each of the following reactions. Also write balanced chemical equation for each reaction.
(i) A reaction in which the reaction mixture becomes warm.
(ii) A reaction in which an insoluble substance is formed. [CBSE, OD, Set 3, 2020]
Answer: (i) Reactions in which the reaction mixture becomes warm and heat is released along with the formation of products are called exothermic reactions. Example of exothermic reactions: Burning of natural gas
CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(g)
CaO + H₂O → Ca(OH)₂
(ii) Reactions in which an insoluble substance is formed is known as precipitation reaction. For example: Solutions of barium chloride and sodium sulphate in water react to give insoluble barium sulphate and the solution of sodium chloride.
Na₂SO₄(aq) + BaCl₂(aq) → BaSO₄(s) + 2NaCl(aq)