Strength of Bonds

[lwon Dis2I]

How do you use the strength of bonds to determine whether a reaction will be endothermic or exothermic?

[alette1a]

If the bonds on the reactant side are overall stronger, the reaction will be endothermic. This is because the reaction requires more heat absorbed to break the reactants' bonds than it releases when forming the products' bonds.

If the bonds on the product side are overall stronger, the reaction will be exothermic. This is because the reaction releases more heat when forming the products' bonds than it requires in breaking the reactants' bonds.

Hope this helps!

[lwon Dis2I]

Thanks for your response! What if the two reactants seem to be neutral and balance each other out? How would you use the products to determine the type of reaction?

[Sedge Greenlee]

Hey Iwon, to respond to your second question if both reactants and products have an equal bond strength, which I'm assuming is extremely rare, I believe the reaction would neither produce nor require heat. I'm not sure what circumstances would ever yield this type of reaction but that's my best guess.

[Katie Nye 2F]

If the bonds on the product side are stronger than the reaction will be exothermic. Less energy is required to break the reactant bonds than is released when forming the product bonds. The opposite is true for endothermic reactions. The reactant side will have stronger bonds because more energy is required to break those than to form the product bonds.

[Jason_John_2F]

i agree, when stronger bonds are being broken they require more energy and when stronger bonds are being formed they release more energy

[Annie Liang 3D]

We can use the strength of bonds to determine whether the reaction is exothermic or endothermic by first figuring out whether the reactants or products have a strong bond. If the reactants side has stronger bonds, the reaction will be endothermic. This is because it takes more energy to break the reactants in order to form products. On the other hand, if the products side has stronger bonds, the reaction will be exothermic. This is because less energy is required to break the reactants in order to form products.

[Gian Boco 2G]

You can use the strength of bonds and bond energies to determine if a reaction is endothermic or exothermic by comparing the sum of the bond energies on the reactants side and that of the products side and then comparing the two. If the reactants have a higher total bond energy or have stronger bonds than the reactants, then the reaction is exothermic. If the products have a greater total bond energy than that of the reactants, then the reaction is likely to be endothermic.