Titration is a method used to prepare salts if the reactants are soluble. Concentration and volumes of reactants can be calculated from titrations.

You can calculate the amount of a substance in moles in a solution if you know the volume and concentration. You can also work out the concentration of an acid reacting with an alkali, or vice versa.

Concentration, amount of solute and volume of solution are linked by this equation:

Concentration in mol/dm^{3} = amount in mol ÷ volume in dm^{3}

This equation can be rearranged to find the amount of solute or volume of solution.

Divide a volume in cm^{3} by 1,000 to convert it to a volume in dm^{3}.

- Question
0.5 mol of solute is dissolved in 250 cm

^{3}of solution. Calculate its concentration.250 cm

^{3}= 250 ÷ 1,000 = 0.25 dm^{3}Concentration = 0.5 ÷ 0.25 = 2.0 mol/dm

^{3}

Rearranging the equation: **amount = concentration × volume**

- Question
Calculate the amount of solute dissolved in 2 dm

^{3}of a 0.1 mol/dm^{3}solution.Amount = 0.1 × 2 = 0.2 mol

Rearranging the equation: **volume = amount ÷ concentration**

- Question
Calculate the volume of a 2 mol/dm

^{3}solution that contains 0.5 mol of solute.Volume = 0.5 ÷ 2 = 0.25 dm

^{3}Note that 0.25 dm

^{3}is the same as 250 cm^{3}(0.25 × 1,000).

Concentrations can also be expressed in grams per decimetre cubed (g/dm^{3}). To convert the two different units of concentration, use the relative formula mass (*M*_{r}).