i need explanation of partition coefficient and two immiscible layers...its for p5.......so i need the complete explanation.....some 1 help me out please....and does any1 know any p5 question based on this two topics ?
- The word 'partition' means a substance X is distributed between two phases in a dynamic equilibrium.
- It is a heterogeneous equilibrium since the 'solute' is distributed between two distinct phases.
- The two phases may be a gas and liquid-solution or, more likely, two immiscible liquids.
The basic expression is:
K
partition = [X(phase 1)] / [X(phase 2)]
Here the K is called the partition coefficient or distribution coefficient. If it involves two immiscible liquids, K has no units.
The partition will involve the distribution of a solute between two immiscible liquid phases, which is a more likely and simpler situation to deal with.
If the solute is in the same molecular state in both liquid-phases, the following simple partition equilibrium expression will apply:
K
partition =
[X(liquid 1)]
----------------
[X(liquid 2)]
K is called the partition/distribution coefficient and has no units and is temperature dependent.
Both concentrations must be in the same units e.g. molarity mol dm-3, g dm-3, mg cm-3 or whatever.
If a substance is added to a mixture which is soluble to a greater or lesser extent in both immiscible liquids, on shaking and then allowing the mixture to settle, the concentrations in each layer become constant. However, there is continual interchange of solute between the liquid layers via the interface i.e. a dynamic equilibrium is formed.
If more of the substance X is added to the system, the solute will distribute itself between the immiscible liquids so that the ratio of the solute concentrations remains the same at constant temperature independently of the total quantity of X in the same molecular state, and that is essentially the partition equilibrium law.
