Mole Fraction: Definitions, Examples, Properties, Symbols and Derivation, Unit, Formula, and Related Quantities

Mole Fraction Overview

The Mole Fraction is the product of the number of molecules in a component divided by the sum of molecules in a mixture. When two reactive components are combined, it is highly helpful. The mole fraction is the ratio of the two components. It is an important chapter in Class 11 that will be covered in all competitive tests, including the IIT exams, the JEE Mains exam, and the NEET exam. 

What is a Mole?

The International System of Units (SI) uses the mole (symbol mol) as the unit of material quantity. How many elementary entities of a certain substance are present in an item or sample is determined by the quantity of that material.

Mole Fraction Definition

The mole fraction is the product of the number of molecules of a certain component in a mixture and its total molecular weight. It is a means to convey how concentrated a solution is. The number of molecules in a mixture of a certain component divided by the overall number of molecules in that mixture is known as the mole fraction. A mole fraction is a quantity that has no units. The mole fraction is denoted by the symbol X.

Mole Fraction Highlights

The following table gives details about the mole fraction-

Examples of Mole Fraction

The mole fraction of the acetone is 0.7 in a solution of 1 mol benzene, 2 mol carbon tetrachloride, and 7 mol acetone. This is calculated by multiplying the total number of moles of the solution's components by the sum of the moles of acetone in the solution-

Number of moles present in Acetone = 7 

Number of moles present in benzene = 1

Number of moles present in carbon tetrachloride = 2

Total number of moles present in the solution overall = 10

Acetone moles divided by the total moles of solution give the acetone mole fraction.

Acetone Mole Fraction = 7/10

Acetone has a mole fraction of 0.7.

Similar to how benzene's mole fraction would be 1/10 or 0.1 and carbon tetrachloride's mole fraction would be 2/10 or 0.2.

Properties of Mole Fraction

The mole fraction's characteristics are as follows-

1. A component's mole fraction in a ternary mixture can be stated as a function of the binary mole ratios and mole fractions of the other components.
2. A mixture with a known mole fraction can be made by subtracting the actual masses of the elements from the total weight.
3. Because it is temperature independent, it is not affected by changes in temperature. 
4. In the case of the mole fraction, it is not required to be aware of the densities of the relevant phases.
5. The measure is symmetrical, therefore the roles of "solvent" and "solute" are switched in the mole fractions where x = 0.1 and x = 0.9.

Mole Fraction Symbols and Denotion

Instead of the conventional Roman X, the lowercase character "chi" is used to represent the mole fraction.

Unit of Mole Fraction

1. The concentration of the solution is shown using the mole fraction. 
2. It is the proportion of the solute or solvent's mole to the sum of all the solution's moles. 
3. It is a dimensionless amount because, as we can see, it is a ratio of two comparable numbers. 
4. Mole Fraction thus lacks a unit.

Mole Fraction Percentage

You can get the mole percentage by multiplying the mole fraction by 100. This is also referred to as amount/amount%. As a result, the mole percent can even go as high as 100 in this case and then return to the mole fraction divided by 100.

Mole Fraction Formula

If two compounds A and B are present in a solution, their respective mole fractions are as follows-

Mole fraction of solute =  (Moles of Solute) / (Total number of moles of the solutes and the solvent).

XA = (mol A) / ( mol A + mol B)

And

XB = (mol B) / ( mol A + mol B)

NOTE: The total mole fractions contained in the given combination equal one. 

XA + XB = 1.

The mole percentage is obtained by multiplying the mole fractions by 100. A unitless and dimensionless statement is a mole fraction. As a result, the mole fraction of each component added together is always equal to one. Please be aware that mole fraction refers to a percentage of molecules, which is distinct from mass fraction because different molecules have different masses.

Related Quantities of Mole Fraction

The following are some of the quantities of mole fraction-

Mass fraction

The mass fraction of a component is its molar mass. Wi is the symbol for it.

The mass fraction equation is-

Mi = The component's molar mass

M = The mixture's mean molar mass.

Molar Mixing Ratio

The term "molar mixing ratio" refers to the mixing of two or more ratios.

Mole Percentage

To obtain a relative figure, one must multiply the computed mole fraction by 100.

Mass Concentration

The amount of a chemical species present in a solution is measured by its concentration.

Read more about the Father of Chemistry.

Advantages of Mole Fraction

The following are some of the benefits of mole fractions include-

1. In the case of an ideal gas mixture, the mole fraction is represented by the ratio of the partial pressure to the total pressure of the mixture.
2. It is not essential to ascertain the phase's density in order to compute the mole fraction.
3. The temperature has never been a factor in the mole fraction.

Disadvantages of Mole Fraction

The following are some of the disadvantages of mole fractions include-

1. The partial pressure of the gas can alter the mole fraction of gases.
2. This hypothesis does not allow for the determination of mass fractions.
3. Volume can have an impact on this phenomenon and the computation of gaseous mixtures.

Read more about the Difference Between Molarity and Molality.

Points to Remember

1. Amount fraction is another name for mole fraction. 
2. Different molecules can have varying masses, and the mass fraction and individual fraction can differ.
3. Molality is the measurement of the total number of moles of a solute in a solvent.
4. Mole fraction, as opposed to molar concentration, does not require knowledge of the densities inside the phases involved.
5. The concentration of the solution is calculated using the Mole Fraction.
6. The total mole fraction will always equal one when all factors are taken into account.