[gloinddark]

during an experiment to find the partition coefficient of iodine in water and iso-octane, the mixture of iodine, iso-octane and water was acidified before allowing the phases to separate. i cannot understand the reason why it was acidified, any help will be appreciated.

[ARGOS++]

Dear gloinddark;

It could be to protect the building of "Triodide" what makes the I₂ much more water-soluble and gives inadequate results for the coefficient.

You may read under "Characteristics" on:   http://en.wikipedia.org/wiki/Iodine#Characteristics 

Addition of strong acid will shift the equilibrium to the left of the following equation:
            http://en.wikipedia.org/wiki/Triiodide#Formation_and_structure 

I hope to have been of help to you.
Good Luck!
                    ARGOS⁺⁺