You can calculate the number of moles of a substance in solution if you know the volume and the concentration. You can also work out the concentration of an acid reacting with an alkali and vice versa.
Divide volumes in cm3 by 1000 to convert it into dm3.
0.5 mol of solute is dissolved in 250 cm3 of solution. Calculate its concentration.
250 cm3 = 250 ÷ 1000 = 0.25 dm3
Concentration = 0.5 ÷ 0.25 = 2.0 mol/dm3
Rearranging the equation: amount = concentration × volume
Calculate the amount of solute dissolved in 2 dm3 of a 0.1 mol/dm3 solution.
Amount = 0.1 × 2 = 0.2 mol
Rearranging the equation: volume = amount ÷ concentration
Calculate the volume of a 2 mol/dm3 solution that contains 0.5 mol of solute.
Volume = 0.5 ÷ 2 = 0.25 dm3
Note that 0.25 dm3 is the same as 250 cm3 (0.25 × 1000).
Concentrations are also expressed in grams per cubic decimeter (g/dm3). Use therelative formula mass (Mr) to convert the two units of concentration.