Mole fraction

The amount of substance (symbol: , often simplified x ), formerly referred to as mole fraction of a component in a mixture is the relative number of particles (atoms / molecules / ions) of this component to the total number of particles of the mixture. It thus belongs to the salary data. However, the molar ratio to each other denotes the relative number of particles of the components. Mole fraction and mole ratio are dimensionless quantities.

Calculation

Amount of substance

Is calculated the mole fraction of component i at the breakdown of the amount of substance of component i, divided by the sum of all quantities of the mixture of m components. The counter runs over all j m components.

The amount of substance of an ingredient in a mixture is between 0 and 1:

The mole fractions of all m components of a mixture add up to 1:

The amount of substance is thus a measure of the fractional number of particles of a component in a mixture and is mainly used in the Tx phase diagrams using. If the mole fraction of 1, the corresponding component is present in pure form; it is 0, it is not included in the mixture. Multiplying specify the mole fraction at 100 percent, so it can also be in the form of percentage size, as so-called mole percent or mole (abbreviation mol%). It is a dimensionless quantity. Since such a measure is very versatile, arising from his numerous applications in various fields, especially chemistry, as well as mineralogy, petrology, materials science and materials science to describe, for example, the composition of rocks, minerals ( solid solutions ) and alloys.

Molar ratio

The molar ratio is the ratio of the amount of a component to the molar amount of the other component:

It is often used in the description of reaction equations and instructions. It is the ratio of the starting materials used in the reaction, shown and referenced to a starting material. Thus, in the oxyhydrogen reaction, hydrogen is reacted with oxygen in the molar ratio 2:1; with respect to oxygen, the term 2 equivalents of hydrogen is often used. The name is derived from the concept of Äquivalentteilchen.

Solutions

For the example of a solution is calculated, the respective mole fraction of the solvent and the dissolved components as follows:

At m dissolved components:

For approximate calculations, it is assumed simplified in the special case that the mole fraction of the component in relation to the solution is negligibly small and you can therefore set the mole fraction of the solvent is equal to 1.