The partition coefficient is modified when the ph of the aqueous phase is adjusted or when a chelating agent is added. the partition coefficient is renamed the distribution coefficient. what is the impact on the extraction of a weak acid into an organic solvent as the ph of the aqueous phase increases? a) as the ph increases the value of d decreases and the percentage weak acid left in the aqueous phase decreases. b) as the ph increases the value of d increases and the percentage weak acid left in the aqueous phase increases. c) as the ph increases, the value of d decreases and the percentage weak acid left in the aqueous phase decreases. d) as the ph increases the value of d increases and the percentage weak acid left in the aqueous phase decreases. e) as the ph increases the value of d decreases and the percentage weak acid left in the aqueous phase increases.

Option E.        

Explanation:

The partition coefficient (D) relates the solute partitioning between two phases, in which the solute extraction from an aqueous phase into an organic phase is represented by:    

S(aq)  ⇄ S(or)

     (1)    

When the pH of an aqueous phase increases by the use of an alkaline solution like NaOH, the solubility of a weak acid, for example, acetic acid, increases in the aqueous phase by the following reaction:        

CH₃COOH + NaOH ⇄ CH₃COO⁻Na⁺ + H₂O     (2)

Therefore, as the pH of the aqueous phase increase, the percent of the weak acid in the aqueous phase increases as a result of acid neutralization (equation 2).          

The increase of the weak acid percentage in the aqueous solution produces a decrease in the partition coefficient, since the inverse relationship between the coefficient partition and the solubility in the aqueous phase (equation 1).                    

So, the correct answer is option E: as the pH increases the value of D decreases and the percentage weak acid left in the aqueous phase increases.        

I hope it helps you!      

it doesn't. it was imagined up in the middle ages.