Question
Distinguish between Endothermic reaction and Exothermic reaction.
✓
Answer
Endothermic reaction:
- In endothermic reaction heat is absorbed from suroundings.
- Sum of enthalpies of products is greater than sum of enthalpies of reactants i.e.$\Sigma_P H>\Sigma_R H$
- Heat of reaction, ΔH is positive.
- Products are less stable than reactants.
- $\begin{aligned} & C _{( s )}+ O _{2( g )} \rightarrow CO _{2( g )} \\
& \Delta H =-394 kJ \end{aligned}$ - This reaction requires supply of thermal energy.
- In exothermic reaction heat is given out to surroundings.
- Sum of enthalpies of products is less than sum of enthalpies of reactants.
i.e. $\Sigma_P H<\Sigma_R H$ - Heat of reaction, ΔH is negative.
- Products are more stable than reactants.
- $\begin{aligned} & N _{2( g )}+ O _{2( g )} \rightarrow 2 NO \\ & \Delta H =+180 kJ \end{aligned}$
- This reaction does not require supply of thermal energy.
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