In the pure state H2O2 is an almost colourless (very pale blue) liquid. Its important physical properties are given in Table 9.4. H2O2 is miscible with water in all proportions and forms a hydrate H2O2.H2O (mp 221K). A 30% solution of H2O2 is marketed as ‘100 volume’ hydrogen peroxide.
It means that one millilitre of 30% H2O2 solution will give 100 mL of oxygen at STP. Commercially marketed sample is 10 V, which means that the sample contains 3% H2O2.