Sodium bisulfate can be made by mixing stoichiometric quantities of sodium hydroxide and sulfuric acid as the following equation shows:
NaOH + H2SO4 → NaHSO4 + H2O
To the resulting aqueous solution" which is not dilute", little charcoal is added. The solution is heated to boiling & is filtered while hot into a beaker over a hot plate. Discard the filter paper. The clear solution is cooled down by using ice/water bath. White crystals of sodium bisulfate will precipitate & they are collected on a filter paper by vacuum filtration. Leave the crystals to dry.