Difference Between Concentration and Molarity

Concentration vs Molarity

Concentration and molarity are two important phenomena in chemistry. Both terms are used to indicate quantitative measurement of a substance. If you want to determine the amount of copper ions in a solution, it can be given as a concentration measurement. Almost all the chemical calculations are using concentration measurements to draw conclusions about the mixture. To determine the concentration, we need to have a mixture of components. To calculate the concentration of each component’s concentration, the relative amounts dissolved in the solution have to be known. Concentration is the term widely used; however, molarity is also a type of concentration measurement.


There are a number of methods to measure the concentration. They are mass concentration, number concentration, molar concentration, and volume concentration. All are given as ratios, where the numerator is representing the amount of the solute, and the denominator is representing the amount of solvent. The way of expressing the solute differs in all these methods. However, the denominator is always the volume of the solvent. In mass concentration, mass of the dissolved solute in one liter of the solvent is given. Likewise, in number concentration, number of solutes, and in molar concentration, moles of solute are given. Further in volume concentration volume of the solute is given. Other than these, concentrations can be given as mole fractions where the moles of the solute are given in relation to the total amount of substances in the mixture. In the same way, mole ratio, mass fraction, and mass ratio can be used to indicate concentration. It can also be indicated as percentage values. According to need, the method of indicating the concentration has to be selected. However, the conversion between these units should be known to chemistry students in order to work with them.


Molarity is also known as molar concentration. This is the ratio of the number of moles of a substance in one volume of a solvent. Conventionally, the solvent volume is given in cubic meters. However, for our convenience we often use liters or cubic decimeters. Therefore, the unit of the molarity is mol per liter/ cubic decimeter (mol l-1, mol dm-3). The unit is also indicated as M. For example, a solution of 1 mol of sodium chloride dissolved in water has a molarity of 1 M. Molarity is the most commonly used method of concentration. For example, it is used in the calculation of pH, the dissociation constants/equilibrium constants etc. Conversion of a mass of a given solute to its molar number has to be done in order to give the molar concentration. To do this, mass is divided by the molecular weight of the solute. For example, if want to prepare a 1 M of potassium sulfate solution, 174.26 g mol-1 (1 mol) of potassium sulfate should be dissolved in one liter of water.


What is the difference between Concentration and Molarity?

• Molarity is a method of expressing concentration, and it is the most widely used method in laboratories.

• Molarity is defined as the ratio between the number of moles of solutes dissolved in one liter of the solvent. Other than this, there are other methods of giving the concentrations with related to different solute measurements.