[chronicconic]

In the lab, it was determined that the bond dissociation energy for a C-H bond is 213kJ/mol?
How much energy would be required to break a single C-H bond?

I decided it was either 213kJ/6.022x10^23 = 3.54 x10^-22kJ, or 213kJ. I'm not sure

[opti384]

I'm pretty sure it's the latter.

[chronicconic]

I can't see how it could be the prior. I mean, 3.54x10^-32kJ seems like a ridiculously small amount of energy to break a C-H bond.

[saden99]

Latter means the second of those mentioned. So he was saying 213kJ seems like the reasonable answer.


And with just that information I would say the same thing. Your calculation doesn't quite make sense...Avogadro's constant has units that you have to take into account (in this case 1/mol). This wouldn't be canceled out anywhere and...I think you'd be left with kJ-mol^-1...which again gets your no where.

This would be a question where intuition plays a role. Yes.....3.54 x10^-22kJ is way to small an amount of energy to break a C-H bond.

[tamim83]

Actually the first answer is very reasonable if you consider the size of a molecule.  Energies should be on the order of 10^-19 J (a few electron-volts).  Trust me, I'm a physical chemist; go with your first answer.

[ifross]

The correct answer is 3.54x10^-19J (your first answer). 213KJ is the energy needed to break 1 mol of bonds, i.e. 6x10^23 CH bonds, so to find out how much energy is needed to break one bond, you divide by this as you did.