General Chemistry - Kinetics and combustion

[ihatebluescrubs]

A couple quick questions that probably simple for you guys and not sticking for me:

What I understand is that:
-bond formation gives off energy and bond breakage takes energy.

However, in a combustion reaction, it releases heat. Why is that combustion is exothermic (releases energy) when breaking bonds (i.e. the carbon carbon bonds) requires energy?

Thanks

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[Jepstein30]

A couple quick questions that probably simple for you guys and not sticking for me:

What I understand is that:
-bond formation gives off energy and bond breakage takes energy.

However, in a combustion reaction, it releases heat. Why is that combustion is exothermic (releases energy) when breaking bonds (i.e. the carbon carbon bonds) requires energy?

Thanks

The bonds formed (creating H20 and CO2) are stronger than the bonds broken (O2 and other reactant).. hence more heat is given off than is taken in.

All bonds take energy to break, so all reactions need some activation energy even if they are exothermic.

 

[Temperature101]

A couple quick questions that probably simple for you guys and not sticking for me:

What I understand is that:
-bond formation gives off energy and bond breakage takes energy.

However, in a combustion reaction, it releases heat. Why is that combustion is exothermic (releases energy) when breaking bonds (i.e. the carbon carbon bonds) requires energy?

Thanks

The energy needed for the reaction to occur is less than total energy released; therefore, the extra energy is released as heat. Hence, exothermic.