CBSE Class 10 Answered

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