Question
Fri April 04, 2014 By: Lilekha N

Dear teacher,

I have a doubt on endothermic and exothermic reactions. Please clarify it.'We have learnt that combustion of carbon in air is an exothermic reaction. But cubustion also requires some heat to ignite.' Why can't we call it endothermic?

Expert Reply
Mon April 07, 2014
Exothermic reaction is a reaction which generates heat, while endothermic reaction consumes heat.
In combustion reaction, to break bonds heat is used up but to create new bonds much more amount of energy is used up.
Thus heat produced is much more than the heat consumed. Hence, the combustion reaction is exothermic reaction.
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