Molar fraction

The molar fraction: X , or the molar percentage ( x% ) is a size used in Chimie and Métallurgie to express the composition of a mixture or a Alliage (i.e. proportions of each component in the mixture). When the chemical species are atoms, one uses also the atomic term percentage.

the molar fraction of a component i' is equal to the report/ratio of the number of moles of this component n_i on the full number of moles of the mixture n_tot .

$x\_i\; =\; \backslash \; frac\; \{n\_i\}\; \{n\_\; \{early\}\}$ what gives $x\_i\%\; expressed\; as\; a\; percentage\; =\; \backslash \; frac\; \{n\_i\}\; \{n\_\; \{early\}\}\; .100$

the sum of the molar fractions of the components of the mixture is equal to the unit.

$\backslash \; sum\; x\_i\; =\; 1$

This size makes it possible to describe the relationship between the numbers of atoms of each species; it is interesting for the mixtures or the alloys Intermétallique S.

Other ways of expressing the composition

There exist several other ways of expressing the composition or the concentration:

Molarity

Molalité

Ppm, Pb

partial Pressure

CH or DH: dilution C entésimale or D écimale, H ahnemanienne, reserved for the Homeopathy.

See too

• Solution (chemistry)

• molar Concentration

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