CBSE Class 10 Science 2020 Outside Delhi Set 3

Question : 1

Total: 6

Identity 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

Solution:

(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)

(Sodiumsulphate)

BaCl2(aq)

(Barium chloride)

→

BaSO4( s)

(Barium sulphate)

2‌NaCl(aq)

(Sodium chloride)

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