Partition Coefficient Formula

Partition Coefficient Formula

In Physics, the Partition Coefficient Formula(P) or partition coefficient (D) is the ratio of the concentrations of a compound in a mixture of two immiscible solvents at equilibrium. A ratio is a comparison of solute solubility in two liquids. However, P is also the concentration ratio of the compound to the non-ionised species. On the contrary, D is the concentration ratio for all types of compounds (both ionised and non-ionised).

Introducing about Partition Coefficient and Distribution Coefficient

The Partition Coefficient Formula is expressed as the concentration ratio of a chemical between two media at equilibrium. It produces gases such as air, liquids such as water or complex mixtures like blood or other tissues. Students are advised to learn Partition Coefficient Formula from Extramarks.

Understanding How Partition is Different From Distribution Coefficient

It is important to know about the partition coefficient, and how it differs from a partition coefficient. The Partition Coefficient Formula happens to be the ratio of the concentrations of the non-ionised species of any compound in a mixture of two immiscible states. Also, to determine the Partition Coefficient Formula of a two-phase system, the two phases must be in balance with each other.

The Partition Coefficient Formula is,



The ratio indicates the solubility of each non-ionized species in the mixture. An aspect that distinguishes the partition coefficient from the partition coefficient is that P refers to the concentration of non-ionised species of a compound, whereas Partition Coefficient Formula is the concentration of both ionised and non-ionised species of any compound.

Partition Coefficient Problems

Problem 1: The concentration of solute in the mobile phase is 5.00 M and in the stationary phase is 7.00 M. Calculate the partition coefficient Kd between water and hexane.


Given the


cm = 5.00 metres

Apply the numbers to the appropriate formula given below

 Kd = 1.4

Problem 2: Consider an aqueous solution of chloroform and water with a Kd value of 6.40 and a solute concentration in the mobile phase of 0.415 M. Find the concentration of the solute in the stationary phase.


Given the

 Kd = 6.40

 cm = 0.415 m

 Substitute the values ​​into the appropriate expressions. CS = 2.656

For more examples and exercises on Partition Coefficient Formula, one can visit Extramarks.

The Multiple Usages of Partition Coefficient & Distribution Coefficient

Both the partition coefficient and the multiple uses of the partition coefficient play important roles in serving these applications in various industries.

  • A pharmacological drug’s partition coefficient greatly affects its ability to reach its intended target in the body. It also depends on the strength of the effect when it reaches its target and how long it stays in the body in an active state. Therefore, the log P of a molecule is the criterion used by chemists to make decisions in preclinical drug discovery. 
  • In pharmacokinetics, the partition coefficient strongly influences the properties of ADME. Therefore, the hydrophobicity of a compound is an important determinant. Furthermore, for drugs to be orally absorbed, they must cross the lipid bilayer of the intestinal epithelium. For effective transport, it must be sufficiently hydrophobic to partition into lipid bilayers. However, it should not be too hydrophobic. Hydrophobicity plays an important role in determining where a drug will be distributed in the body after absorption. Consequently, how they are metabolised and excreted is guaranteed.
  • Pharmacodynamics: Hydrophobic effects happen to be the driving force for drug binding to receptor targets. In contrast, hydrophobic drugs are toxic due to their long retention. They are widely distributed in the body and are less selective in binding to proteins. Finally, they are often extensively metabolised. Rarely, metabolites can react chemically. Therefore, it is recommended to make drugs more hydrophilic while maintaining adequate binding affinity to therapeutic protein targets. 
  • Pesticide research: The applications and importance of partition coefficients are not limited to the medical field. It is also used in agrochemical science. Hydrophobic pesticides and herbicides are more active. In fact, hydrophobic pesticides have long half-lives. Therefore, they are more likely to have a negative impact on the environment.
  • Environmental Science can give insight into Partition coefficients to predict the mobility of radionuclides in groundwater. The metallurgical partition coefficient is an important factor that determines various impurities and their distribution between solidified and molten metals. This is an important parameter for zonal smelting refining. This shows how effectively contamination can be removed by directional solidification.
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Thermodynamics Formulas
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FAQs (Frequently Asked Questions)

1. ow important is the Partition Coefficient Formula to a pharmacist?

According to the Partition Coefficient Formula application, the partition coefficient is usually very useful in estimating drug distribution in the body. In fact, hydrophobic drugs with high octanol-water partition coefficients are highly distributed in hydrophobic regions, such as the lipid bilayers of cells. 

2. Is Partition Coefficient Formula and distribution coefficient the same?

Partition Coefficient Formula, According to the information in the PDF, there is an important difference between partition coefficient and distribution coefficient. The main differentiating factor is therefore the fact that the partition coefficient is the total concentration of the non-ionised species of the compound, whereas the distribution coefficient is the concentration of both the non-ionized and ionised species of the compound. And the partition coefficient is not equal to the distribution coefficient.