Distribution Law
The principle that a solute distributes itself between two immiscible solvents in a constant ratio at fixed temperature.
Formula / equation
K_D = C_organic / C_aqueous
Unit
Dimensionless
In depth
Also called the Nernst partition law, it holds provided the solute exists in the same molecular form in both phases. The law underlies liquid–liquid extraction and explains why repeated extraction with small portions removes more solute than one large portion.
Examples in the real world
Iodine distributing between water and carbon tetrachloride with a ratio of about 1:85.