The dilute solutions of hydrogen peroxide cannot be concentrated by simple heating. This is because hydrogen peroxide readily decomposes below its boiling point.So, to obtain a concentrated solution of hydrogen peroxide, the following steps are needed to done – •The diluted solution is carefully heated on a water bath. Doing slow evaporation, helps the release of water molecules and we obtain 50% solution of H₂O₂.•The 50% solution is placed in vacuum desiccator over concentrated sulphuric acid. The dehydrating nature of sulphuric acid absorbs water vapours and we get 90% solution of H₂O₂. •The 90% solution of H₂O₂ is then subjected to distillation under reduced pressure. Water distils over at 303 – 313 K and we get 99% pure H₂O₂ solution.