Bond enthalpies

[Shane_Yu_3K]

Hello,

Can anyone explain when bond enthalpies are positive and when they are negative?

Thank you!

[Ayaan_Ekram_2J]

Hello!

Bond enthalpies are negative when forming bonds and positive when breaking bonds because energy is needed to break bonds and energy is released when forming bonds. A phrase a teacher once taught me that helps me remember this is “breaking up is hard to do” so breaking bonds requires energy. I hope this helps!

[Kayla Tran 3C]

Forming bonds releases energy so it would be negative, while breaking bonds requires energy so it would be positive.

[905695298]

Forming bond releases energy so the enthalpy is negative, while breaking bond requires energy so the enthalpy is positive.

[Jessica Servoss 1H]

If you look up the bond enthalpies of certain elements, the chart will have them all listed as positive due to breaking bonds requiring energy. But when you are forming bonds on the products side, the sign must be flipped to negative since energy is released when bonds are formed.

[kareena_prasad]

When bond enthalpy is positive, it results in the breaking of the bond. When the bond enthalpy is negative, it results in the formation of a bond.