[kdeyre]

An unknown weak organic acid is contaminating a manufacturers processing water at a level of 0.10M. When twenty mL of this water is shaken with 10mL of ether, it is determined by titration that 0.5mmol of the acid remains in the aqueous layer. A pH meter in the aqueous layer reads 3.21.

a) What is the distribution ratio for this system?
b) What is the partitioning coefficient for this system?
c) Further analysis reveals the unknown contaminant to be a saturated aliphatic of MW = 88. What is it?. Prove it.

For part a, I calculated the concentration remaining in the aqueous layerusing:
c=n/v=0.0005mol/0.020L=0.025M which gives a distribution ratio of 3.

For part b, I am completely lost.
For part c, I assume I compare distribution ratios/partitioning coefficients for known compounds to my results?

Any help would be greatly appreciated.
Thanks.

[Pradeep]

For part b, First you have to derive a relation for distribution coefficient (Kd), acid dissociation constant (Ka) and distribution ratio (D). You have to calculate the Ka of the acid also by using available data. Try your self and, please let us know if you need more help.