Molar concentration

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Molar concentration, or molarity, or simply concentration, is a term in physical chemistry. It measures the concentration of a solution or mixture.

In chemistry, the molar concentration, c_i is defined as the amount of a constituent n_i (usually measured in moles – hence the name) divided by the volume of the mixture V:[1]

c_i = \frac {n_i}{V}

The volume V in the definition c_i = n_i/V refers to the volume of the solution, not the volume of the solvent. One litre of a solution usually contains either slightly more or slightly less than 1 litre of solvent because when a substance dissolves in a solvent it causes volume of liquid to increase or decrease.

The reciprocal quantity represents the dilution (volume) which can appear in Ostwald's law of dilution.

References[change | change source]

  1. International Union of Pure and Applied Chemistry. Amount concentration, c. Compendium of chemical terminology, internet edition. [1]