What do you mean by exothermic and endothermic reactions? Give examples.

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Solution

1. Exothermic reaction
a. Definition- Reaction in which heat energy is given out.
b. Example-
Generally combination reactions are exothermic in nature.
Combination reaction- Reaction in which two or more reactants combine to form product . $A + B \to C$
Combustion of ethene
$C {}_{2}H {}_{6}(g) + O {}_{2}(g) \to CO {}_{2}(g) + H {}_{2}O (l) + Heat$
(Ethene) (Oxygen) (Carbon di oxide) (Water)
Since heat energy is given out along with formation of product in this reaction so it is an exothermic reaction.
2. Endothermic reaction
a. Definition- Reaction in which heat energy is absorbed.
b. Example-
Generally decomposition reactions are endothermic in nature.
Decomposition reaction- Reaction in which reactant in broken down into two or more products in presence of heat, light or electricity. $A \to B + C$
Thermal decomposition of lead nitrate
$2 Pb (NO {}_{3}) {}_{2}(s) \overset{heat}{\to} 2 PbO (s) + 4 NO {}_{2}(g) + O {}_{2}(g)$
(Lead nitrate) (Lead oxide) (Nitrogen dioxide) (Oxygen)
Since heat energy is absorbed in this reaction to break down bonds in reactants hence it is an endothermic reaction.

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Similar questions

What do you understand by exothermic reaction and endothermic reaction? Give one example of each type.

(a) What do you understand by exothermic and endothermic reactions ?

(b) Give one example of an exothermic reaction and one of an endothermic reaction.

(i) Buring of natural gas (ii) Photosynthesis

(iii) Electrolysis of water (iv) Respitation

(v) Decomposition of calcium carbonate

Define exothermic and endothermic reactions. Give two examples of each.

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