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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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