CBSE Class 10 Science 2020 Outside Delhi Set 3

Question : 1 of 6

Marks: +1, -0

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

{\CH}_4( {\g})+2 {\O}_2( {\g}) →\; {\CO}_2( {\g})+2 {\H}_2 {\O}( {\g}) {\CaO}\;+ {\H}_2 {\O} → {\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.

{{\Na}_2 {\SO}_4( {\aq})}↙{\text "(Sodiumsulphate)"}+{ {\BaCl}_2( {\aq})}↙{(\text "Barium chloride")} → { {\BaSO}_4( {\ s})}↙{\text "(Barium sulphate)"}+{2 {\NaCl}( {\aq})}↙{\text "(Sodium chloride)"}

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