[Mo100]

I understand partition coefficients and what they represent, however I'm struggling to get to grips with some of the forms the questions can come in through an exam... For instance:

0.2 mol of ethanol and 0.2 mol of methanoic acid are mixed with a few drops of concentrated sulphuric acid catalyst in an empty reaction vessel. After equilibrium is established, it is found that 0.15 mol of the ester, ethyl methanoate, has been formed.
The equation for the reaction taking place is:
C₂H₅OH (l) + HCOOH (l) HCOOC₂H₅ (l) + H₂O (l)

Calculate the equilibrium constant, K, for the reaction under these conditions.

It tells me that the answer is 9 at the back of the book... but I have no idea how you get there... can anyone help?!
Thanks,
Mo

[Borek]

Doesn't look like you need partition coefficients for anything here. Just use stoichiometry to find amounts of the substances and plug into the Kc formula.

[Mo100]

Christ. I'm such a numpty... thanks!