If the moles of solute are not given, then convert the mass of the solute from grams to moles. The mass can be obtained by weighing the solute on a scale. Obtain the molecular weight of the solute from the periodic table. Divide the grams of solute by the molecular weight. This value is the number of moles present in the solute.
The volume of solution should be calculated. If not given, the volume can be measured through the use of a volumetric flask or beaker. It is important to make sure this is the final volume of solution, not the volume of the solute or solvent.
Take the number of moles of solute obtained in Step 1 and divide it by the total liters of the final solution obtained in Step 2. This value represents the molarity of the solution. The final unit must be in molar, signified by M.