Molarity (M) is defined as the number of moles of solute per liter of solution.



Molality (m) is defined as the number of moles of solute per kilogram of solvent.



Although their spellings are similar, molarity and molality cannot be interchanged. Compare the molar and molal volumes of 1 mol of solute dissolved in CCl₄ (d = 1.59 g / mL)

By definition, a 1 M solution would contain 1 mol of solute in exactly 1.00 L of CCl₄ , and a 1 m solution would contain 1 mol of solute in 629 mL of CCl₄ . 1 kg of CCl₄ x  (1000 g /  1 kg) x (mL / 1.59 g) = 629 mL CCl₄

Normality (N) is another ratio that relates the amount of solute to the total volume of solution.

It is defined as the number of equivalents per liter of solution:



There is a very simple relationship between normality and molarity:

N = n × M (where n is an integer)

For an acid solution, n is the number of H⁺ provided by a formula unit of acid.

example: A 3 M H₂SO₄ solution is the same as a 6 N H₂SO₄ solution.

For a basic solution, n is the number of OH^- provided by a formula unit of base.

example: A 1 M Ca(OH)₂ solution is the same as a 2N Ca(OH)₂ solution.

Remember!The normality of a solution is NEVER less than the molarity.