Radical Rate Determining Step

[DrRichand1]

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In the initiation step of a radical reaction, obviously the rate determining step, is the formation of the radical always exothermic? I thought i would be enothermic since heat and light are usually need to get the thing going?

 

[chiddler]

where did you read it is exothermic? the only way that is possible is if it is more stable than reactant.

with regards to the whole reaction, it may be possible for a reaction to be endothermic though, if entropy increases. maybe if a gas evolves or something like that.