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sandbeda
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Homework Statement
Derive an expression for equilibrium concentrations in terms of formality f (and Keq) for the compounds in the the equilibrium reactions shown bellow.
Homework Equations
A2 + 2S <---> 2SA
SA <---> S + A
Where S is a substrate (THF) and A is an adduct (BH3). Delta G and thus Keq have been calculated previously. We are supposed to use an ICE-table.
Keq can be expressed in terms of mole fractions, which can be expressed in terms of a,b,f and m (obtained from eq in the ICE table), and then using the Keq for each reaction I need to solve for a and b (to plug into the equilibrium equations obtained from the ICE table, and thus find equilibrium concentrations in terms of formality f).
The Attempt at a Solution
f = formality, m = coefficient allowing use to write formality of S in terms of f
a and b are simply coefficients to express change. Periods are used instead of spaces because extra spaces are deleted when saved.
...A2...+...2S <--->...2SA....SA <--->...S...+...A
I...f....mf....0.....0...0...0
C1...-af.....-2af...+2af...+2af.....-2af
C2......+2bf...-2bf....-2bf...+2bf...+2bf
eq...f(1-a)...2f(2b-2a+m)...2f(a-b)...2f(a-b)...2bf...f(2b-2a+m)
there are several approximations I can make: m>>b>a. I can always end up with the demoninator of the approximated mole fraction to be 2fm, but I can't seem to make any approximations to solve for a and b. If you are unfamiliar with such procedures I can explain in more detail, for some reason when I post the formating of the ICE-table is changed and makes it very difficult to read. SOMEBODY PLEASE HELP ME!
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