# Common units of Concentration

Chemists use grams per cubic decimetre. Remember that 1000 cubic centimetres (cm3) equals 1 cubic decimetre (dm3) also equals 1 litre (L).

We note that cm3 are sometimes called millilitres (mL).

E.g. if l0 g of glucose are dissolved in water and made up in a volumetric flask to 1000 cm3, then the concentration of glucose in the flask is equal to 10 grams per cubic decimetre or 10g.dm-3.

E.g. similarly if l0g of glucose are dissolved in water and made up to 100cm3, the concentration is l0 g in 100 cm3 or 100g dm-3.

Concentrations are often expressed in terms of relative unites (e.g. percentages) with three different types of percentage concentrations commonly used:

Mass Percent = [(Mass of Solute) / (Mass of Solution)] * 100%

Volume Percent = [(volume of Solute) / (volume of Solution)] * 100%

Mass/Volume Percent = [(mass of Solute) / (volume of Solution)] * 100%

A volumetric flask is very accurate way to measure a volume, when filled exactly to line. It comes in different sizes.