Question

In Organic Chemistry, breifly describe theory behind extraction. Why it happens, how it happens, and talk about the distrubution coefficient K. K=C1/C2

Answer 1

extraction is the process by which a subtance can be removed into a solvent into which it is more soluble from a solvent in which it is less soluble. It works on the princoiple of distribution coefficient. It is useful fro extracting a subtance from a mixture selectively or to remove impurities. Distribution coefficient is the parameter which quantifies the differences in the solubility in different solvents. Extraction occurs due to the difference in solubilty of a solute between two different solvents. Taking a simple example, sugar is slightly soluble in oil. If you dissolve it in oil and put that in the separating funnel and then slowly pour water in, water forms the bottom layer and the oil forms the top layer because water is denser. Sugar is more soluble in water than in oil. At this point, the oil still contains sugar. Now the separating funnel is shaken. the contant area between the two phases increases and thus the sugar moves into the water into which it is more soluble.

K=C1/C2 in this expression K is the distribution coefficient, C1 is the concentration in solvent 1 and C2 is the concentration in the solvent 2. By convention solvent 1 is usually the organic phase and aqueous(water) is solvent2 .It thus represents the ratio in which the substance will be distributed in the two solvents