What Is Mole Fraction?

The ratio of the amount of the substance B in the mixture to the sum of the amounts of the components of the mixture is called the mole fraction, and is represented by the symbol x _B.

The molar fraction refers to the ratio of the amount of the solute n _B of the substance _B in the mixture to the total amount of the substance n in the mixture, and is represented by the symbol x _B. The SI unit of the molar fraction is 1, that is, there is no unit.

Conversion of mass fraction w and mole fraction x (take two components as an example)

If the solution needs to convert the volume fraction into the mole fraction, you need to convert the mass fraction by density first and then use the above formula.

It can be known from its definition expression that the mole fraction influencing factor can only be the amount of the substance of a certain substance and the amount of the total mixture of substances, and the factors such as temperature, pressure, and state do not affect the size of the mole fraction.

Example ^[2]

Molar fraction of an organic mixture

An ethanol solution contains 2mol of water and 3mol of ethanol. What is the molar fraction of ethanol and water?

Solution: x _{water =} n _{water / [} n _{water +} n _{ethanol] = 2mol / [2mol + 3mol] = 0.4}

x _{ethanol = n ethanol / [ n water + n ethanol] = 3mol / [2mol + 3mol] = 0.6}