Molar Concentration Formula

Molar concentration describes the concentration of the solute in a solution. Molar concentration is mostly measured in molarity which is described by dissolving the total number of moles of solute per litre of solution,i.e., M = mol/L.

The image given below gives the formula for the molar concentration of any solution.

Let's learn about molar concentration in detail in this article.

Molar Concentration

Molar concentration tells us about the amount of solute that any solution contains. Thus, molar concentration is of great importance for performing acid-base titration reactions in which finding the exact concentration of acid and base is of key importance.

As the name suggests the molar concentration tells the concentration of the solute in terms of its mole. Molarity and Normality are two types of molar concentration which are widely used in chemistry and related field.

Molar Concentration Formula

The molar concentration of a solution is calculated as the ratio of the amount in moles to the volume of the given solution. Its formula is given as follows:

Molar Concentration = Amount in moles/Volume of the solution

How to Calculate Molar Concentration?

The molar Concentration of any solution can easily be calculated by following the steps given below,

Step 1: Mark the weight of the given solute in grams.

Step 2: Calculate the moles of solute by dividing it by its molecular mass.

Step 3: Divide the moles of solute obtained in step 2 with the volume of solvent (in litre).

Step 4: Simplify the value and add 'M' as the unit.

Application of Molar Concentration Formula

Molar Concentration Formula is used in various fields of science.

• It is used to find the concentration of the solution, i.e. used for finding molarity, normality and others.
• Molar concentration formula finds its application in titration reactions.
• It is used to get the right amount of reagent which reacts with other specific reagents, etc.

Read More:

• Concentration of a Solution
• Mole fraction
• Molality

Solved Examples of Molar Concentration

Example 1: If 16.35 mL of an AgNO₃ solution reacts with 0.0003017 kg of KIO_3, find its concentration.

Solution:

AgNO₃ + KIO₃ = AgIO₃ + KNO₃

Number of moles in KIO₃ = Mass / Molar mass

m = (0.3017 g) / (214.0 g/mol)

    = 0.0014 mol

Number of moles in AgNO₃ = 0.00141 mol

Given, Volume = 16.35 ml = 0.01635 l

Concentration of AgNO₃ = Moles/Volume 

Concentration of AgNO₃ = (0.00141)/(0.01635) 

                                       = 0.08624 M

Example 2: Find the molarity of 4 g of caustic soda, if it was in 200 ml of solution.

Solution:

Mass = 4 g

Volume = 200 ml = 0.2 litre

Molar mass of caustic soda = 23 + 16 + 1 g

                                           = 40 g

Mole = Mass/Molar Mass

         = 4g / 40g
         = 0.1 mole

Molarity = mole / volume
              = 0.1 /  0.2
              = 0.5 M

Example 3: 15 g sodium sulphate was used to make a solution. The solution has a volume of 125 ml. Find the molarity of the sodium sulphate solution supplied.

Solution:

Molar mass of sodium sulphate = 23 × 2 + 32 + 16 × 4 = 142 g

Number of moles in sodium sulphate = 15/142 = 0.106

Volume of the solution = V = 0.125 l

Molarity = n / V

              = 0.106 / 0.125
              = 0.85 M