Re: energy in the tank

["John S. Denker" <jsd@MONMOUTH.COM>]

Daniel Schroeder2 wrote:
...
> the bond joining two H atoms
> into an H2 molecule stores -4.5 eV of energy.

For the Nth time I ask, relative to what?

I actually know the answer:  The bonded state is 4.5
volts below the isolated neutral atoms state...  But my
point remains that there is no 11th commandment that
requires us to measure energy relative to isolated
neutral atoms.  That is merely a choice that is
convenient in some cases and not convenient in other
cases.

You can choose whatever you like, but you can't
prevent other people from choosing what they like.

I could easily choose an energy reference 100 eV
lower than yours, and say that the bond stores +95.5 eV,
on a scale where the isolated neutral atoms stored
+100 eV.  Everything is relative.

You could say that the _bonding_process_ (not the bond
itself) is exothermic to the tune of 4.5 eV and I wouldn't
have a problem with that.

> You can still
> say that the total energy of the molecule is positive if
> you like (and in fact, I would endorse this position because
> the rest energy of the molecule is positive).

OK.