Molarity
The concentration of a solution expressed as moles of solute per litre of solution.
Formula / equation
M = n / V
Unit
M (mol/L)
In depth
Molarity is the most widely used concentration unit because it lets volume measurements be converted directly into amounts. Its drawback is temperature dependence: solution volume expands on heating, so the molarity of a fixed sample falls slightly as it warms.
Examples in the real world
Dissolving 58.44 g of NaCl and making up to 1.000 L gives exactly 1.000 M; concentrated HCl is about 12 M.