W8 Extraction

Question 1

what Is extraction

Answer 1

method to separate compounds or metal complexes based on their relative solubilities in two different immiscible liquids, usually water and an organic solvent

Question 2

definition of partition coefficient

Answer 2

the ratio of concentrations of a compound in a mixture of two immiscible solvents for neutral compounds

K = conc of solute in phase 1 / conc of solute in phase 2

phase 1: solvent that solute is initially dissolved in (bottom layer)

phase 2: extraction solvent (top layer)

Question 3

When performing liquid-liquid extractions, what does shaking the separation funnel changes?

Answer 3

increases the rate at which partitioning reaches equilibrium

Question 4

how does extraction efficiency changes with pH when solute is an acid or base

Answer 4

acidic solutes: put in higher pH > more deprotonated > more soluble in aqueous layer > extraction efficiency increases

basic solutes: put in lower pH > more protonated > more soluble in aqueous layer > extraction efficiency increases

Question 5

definition of distribution coefficient

Answer 5

the ratio of concentrations of a compound in a mixture of two immiscible solvents for compounds that ionises in the solvents

Question 6

when to use which fraction equation in acid base extraction

Answer 6

extraction from aq to organic phase : use Vorg x D

extraction from organic to aq phase: use Vaq/D