From sodium peroxide (Merck’s METHOD)Calculated amount of sodium peroxide (Na2O2) is gradually added to an ice-cold solution of 20% H2SO4 in small lots with constant stiring.Na2O2 + H2SO4 → Na2SO4 + H2O2Upon cooling, crystals of Na2SO4.10H2O separate out and the resulting solution contains about 30% H2O2. The solution also contains some dissolved Na2SO4, but it does not interfere with the reactions of H2O2. A pure sample of H2O2 may, however, be prepared by VACUUM distillation.2. From barium peroxide-Laboratory method of preparation.Hydrogen peroxide is prepared from barium peroxide by the following METHODS:(a) By the action of dilute sulphuric acid. Apaste of HYDRATED barium peroxide (BaO2.8H2O) is prepared in ice – cold water and then added slowly to an ice-cold solution of 20% H2SO4.BaO2.8H2O + H2SO4 → BaSO4 + H2O2 + 8H2O The white precipitate of BaSO4 is REMOVED by filtration leaving behind a dilute solution (5%) of H2O2. In this method, anhydrous barium peroxide can not used since the precipitated BaSO4 forms a protective layer around unreacted barium peroxide thereby preventing the further reaction