How can we say from a set of reactions that it is endothermic or exothermic by only reactions?

Asked by Amit Gautam | 8th Nov, 2013, 02:29: PM

Expert Answer:

To determine whether the reaction is exothermic or endothermic only by looking at the reaction, following method will be helpfull:
 
If the reaction is Exothermic, the term- 'Heat' or 'Δ' sign will be written on the product side (R.H.S.).
 
If the reaction is Endothermic, the term- 'Heat' or 'Δ' sign will be written on the reactant side (L.H.S.).
 
For example:
 

Exothermic reaction

The chemical reactions which proceed with the evolution of heat energy are called as exothermic reactions.

A  +  B  →  C  +  Δ


For example:

2SO2  +  O2  2SO3 Δ

CaO  +  H2O  →  Ca(OH)2  +  Δ

Endothermic reactions

The chemical reactions which proceed with the absorption of heat energy are called as exothermic reactions.

A  +  B  +  Δ   →  C 

For example:

C  +  H2O  +  Δ  →  CO  +   H2

N2  +  O2  +  Δ     2NO

Answered by Hanisha Vyas | 8th Nov, 2013, 05:50: PM

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