Coomber's relationship can be used to describe how the

internal pressure Internal pressure is a measure of how the internal energy of a system changes when it expands or contracts at constant temperature. It has the same dimensions as pressure, the SI unit of which is the pascal. Internal pressure is usually given the ...

and

dielectric constant The relative permittivity (in older texts, dielectric constant) is the permittivity of a material expressed as a ratio with the electric permittivity of a vacuum. A dielectric is an insulating material, and the dielectric constant of an insul ...

of a

non-polar In chemistry, polarity is a separation of electric charge leading to a molecule or its chemical groups having an electric dipole moment, with a negatively charged end and a positively charged end. Polar molecules must contain one or more polar ...

liquid Liquid is a state of matter with a definite volume but no fixed shape. Liquids adapt to the shape of their container and are nearly incompressible, maintaining their volume even under pressure. The density of a liquid is usually close to th ...

are related. As

p_i=\left(\frac\right)_T\,

, which defines the internal pressure of a liquid, it can be found that:

p_i = n \cdot I \cdot b(T) \frac

where *

N

is equal to the number of molecules *

I

is the

ionization potential In physics and chemistry, ionization energy (IE) is the minimum energy required to remove the most loosely bound electron of an isolated gaseous atom, positive ion, or molecule. The first ionization energy is quantitatively expressed as :X(g) ...

of the liquid *

b(T)

is a

temperature Temperature is a physical quantity that quantitatively expresses the attribute of hotness or coldness. Temperature is measurement, measured with a thermometer. It reflects the average kinetic energy of the vibrating and colliding atoms making ...

dependent relation based on numerical constants of the pair summation from inter-particle geometry *

\alpha

is the

polarizability Polarizability usually refers to the tendency of matter, when subjected to an electric field, to acquire an electric dipole moment in proportion to that applied field. It is a property of particles with an electric charge. When subject to an elect ...

V

is the

volume Volume is a measure of regions in three-dimensional space. It is often quantified numerically using SI derived units (such as the cubic metre and litre) or by various imperial or US customary units (such as the gallon, quart, cubic inch) ...

of the liquid where for most non-polar liquids

n=1

References

* Meeten, G.H.,
Theoretical Basis for Coomber's Relationship
, ''Nature'' Vol. 223, August 23, 1969 Physical chemistry {{physical-chemistry-stub