distribution coefficient = K =
= (concentration of solute in solvent 2) / (concentration of solute in solvent 1)
where:
• The concentration of solute can be as weight per volume or moles per volume since the coefficient is a ratio and the molecular weight for the solute is constant.
Parameters:
(1) distribution coefficient K
(2) C2 = solute concentration in solvent 2
(3) C1 = solute concentration in solvent 1
(4) V2 = volume of solvent 2
(5) V1 = volume in solvent 1
(6) I = initial weight in solvent 1 before extraction
(7) F = final weight in solvent 1 after extraction
K = C2 / C1 =
= ((I - F) / V2) / (F / V1)
K * F / V1 = (I / V2) - (F / V2)
K * F *V2 = (I * V1) - (F * V1)
F =
= (I * V1) / ((K * V2) + V1)
weight of solute extracted into solvent 2 =
= I - F
A series of extractions using a smaller volume of solvent is slightly more efficient than a single extraction done with the same total volume of solvent.
