Bond Enthalpy

[Sofia Ban]

What is bond enthalpy and why is it always a positive value?

[Dina Marchenko 2J]

Bond Enthalpy is the enthalpy (essentially the energy) needed to break a bond. All bonds require an input of energy in order to be broken (see bond potential energy graph) and a positive enthalpy signifies that energy must be put in. This is why all bond enthalpies are positive. The bond enthalpy of H2 is the energy required to break the covalent bond between the 2 H atoms.

[cassidysong 1K]

^^ bond enthalpy is always positive because by definition the energy is always being put in.

[Jasmine Vallarta 2L]

requires energy > 0
releases energy < 0

[DLee_1L]

Another way to look at it is that Endothermic reactions require heat so + energy/heat and Exothermic reactions give off heat so energy/heat.