Lecture Question

[alanaarchbold]

In one of the examples from Monday's lecture, O2 didn't have any delta HF value. I was wondering why that is?

[Jordan Lo 2A]

If you mean delta H formation, I think it's because we measure delta H formation relative to what the compound "normally" is. At 25 degrees Celsius and 1 atm, oxygen is usually O2(g). So, it doesn't take any additional energy to transform O2(g) from O2(g)

[Max Hayama 4K]

The reason why O2 has a standard enthalpy of formation of 0 is because diatomic oxygen is the most stable in this form, therefore it requires no change to achieve this state!

[Sophia Ding 1B]

Yeah just to re-iterate, the standard enthalpy of formation has to always do with getting something to its most stable form; so for diatomic molecules (like O2) it is already in its most stable form, thus its standard enthalpy of formation would be 0.