Solute concentration in a solution can be expressed in many ways. Molarity is the most commonly used unit to express concentration of a solute in a solution.

Molarity is defined as concentration of a solute in moles per liter. 

Molarity = amount of solute (in mole)solution volume (in liter)


Mole = amount of substance (in gram)Molar mass (= molecular weight)



Molarity = amount of substance (in gram) / molar mass (= molecular weight)solution volume (in liter)

For example, 1 M NaOH solution contains 1 mole in a liter of solution. 1 mole of NaOH is equal to 40 g of NaOH. In other words, 1 M NaOH solution contains 40 g of NaOH in a liter of solution. So to prepare 1M NaOH solution, 40 g of NaOH is dissolved in water to a final volume of 1 Liter.


Molar mass (= molecular weight) of solute: g/mole

Amount of the solute: g

Volume of the solution: ml

Molarity of the solution: M

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