"Multi-Concept Problem"
Consider the reaction S8(g) --> 4 S2, for which (Delta)H = +99kJ.
(b) The average S-S bond dissociation energy is 225kJ/mol. Using the value of (Delta)H given above, what is the S=S double bond energy in S2(g)?
It mentions in question (a) that S
8 is cyclic. (cyclooctasulphur I believe)
The solutions manual multiplies the S-S diss. energy by 8 when solving for the S=S bonds according to:
(Delta)H = D(reactant bonds) - D(product bonds)
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Why?This is what I was going to do at first, but after drawing the structure it appeared to me as incorrect.
It seems to translate as: S
8(g) --> 8 S(g) --> 4 S
2Why not S
8(g) --> 4 S
2 all in one shot?
Couldn't only 4 S-S bonds be broken, and four new bonds be made from the electron gained by each S atom?
So which mechanism is correct?
All other examples I have seen involve diatomic molecules only... *yawn!*
EDIT: Ok. I'm tired. I just realized the why the calculation involves all the bonds. Just need insight on mechanism for my curiosity. Thanks.