Question

If a reaction is exothermic, are the attractive forces between the reactants stronger or weaker than the attractive forces between the products? Why?

Answer 1

This isn't a very well-posed question. All you know, since the reaction liberates heat, is that more energy is released forming bonds in the products than is absorbed in breaking the bonds in the reactants. (emcrazy has this backward, incidentally: recall that breaking bonds always absorbs energy.)

This tells you that in at least some cases the attractive bonding forces acting between the atoms of the producs are stronger than the bonding forces that acted between the atoms of the reactants. So the answer to your question is probably "weaker."

But the question is badly posed because the bonding forces will vary significantly between different pairs of atoms in both the reactants and products. Some forces in the products will be stronger than others, and the same in the reactants. Some forces in the products will be stronger than those in the reactants, and vice versa. You can't really make a blanket statement about ALL the forces in the reactants or products. About all you can say is (1) the total bonding energy in the products must be greater, since energy is released during the reaction, or (2) what I said above, that in at least some cases, the bonding force between atoms of the products must be stronger than that between the atoms of the reactant.

Answer 2

@emcrazy14
are sure about:Bond breaking is exothermic while bond making is endothermic
it sounds more logical the other way around..?

Answer 3

@mos1635: I'm sorry. I wrote it the other way round. >_<