Dilution ratio

In chemistry and biology, the dilution ratio and dilution factor are two related (but slightly different) expressions of the change in concentration of a liquid substance when mixing it with another liquid substance. They are often used for simple dilutions, one in which a unit volume of a liquid material of interest is combined with an appropriate volume of a solvent liquid to achieve the desired concentration. The diluted material must be thoroughly mixed to achieve the true dilution.

For example, in a solution with a 1:5 dilution ratio, entails combining 1 unit volume of solute (the material to be diluted) with 5 unit volumes of the solvent to give 6 total units of total volume.

In photographic development, dilutions are normally given in a '1+x' format. For example '1+49' would typically mean 1 part concentrate and 49 parts water, meaning a 500ml solution would require 10ml concentrate and 490ml water.

Dilution factor[edit]

The "dilution factor" is an expression which describes the ratio of the aliquot volume to the final volume. Dilution factor is a notation often used in commercial assays. For example, in solution with a 1/5 dilution factor (which may be abbreviated as x5 dilution), entails combining 1 unit volume of solute (the material to be diluted) with (approximately) 4 unit volumes of the solvent to give 5 units of total volume. The following formulas can be used to calculate the volumes of solute ( $V solute$ ) and solvent ( $V solvent$ ) to be used:^[1]

{\begin{aligned}V_{\rm {solute}}&={\frac {V_{\rm {total}}}{F}}\\[4pt]V_{\rm {solvent}}&=V_{\rm {total}}-V_{\rm {solute}}\end{aligned}}

where

V total

is the desired total volume, and

F

is the desired dilution factor number (the number in the position of

F

if expressed as "

1/ F

dilution factor" or "

xF

dilution"). However, some solutions and mixtures take up slightly less volume than their components.

In other areas of science such as pharmacy, and in non-scientific usage, a dilution is normally given as a plain ratio of solvent to solute. For large factors, this confusion makes only a minor difference, but in precise work it can be important to make clear whether dilution ratio or dilution factor is intended.

References[edit]

^ Dr. Walker. "Dilutions" (PDF). Weber State University. Retrieved 2023-05-06.

Dilution factor[edit]

References[edit]

See also[edit]