Sodium bisulfate

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Sodium bisulfate
Sodium bisulfate.jpg
Sodium bisulfate from the store
IUPAC name
Sodium hydrogen sulfate
Other names
Bisulfate of soda
Sodium acid sulfate
Molar mass 120.06 g/mol (anhydrous)
138.07 g/mol (monohydrate)
Appearance Colorless solid
Odor Slight, acidic
Density 2.742 g/cm3 (anhydrous)
1.8 g/cm3 (monohydrate)
Melting point 58.5 °C (137.3 °F; 331.6 K) (monohydrate)
315 °C (599 °F; 588.15 K) (anhydrous, decomposes)
Boiling point Decomposes
28.5 g/100 ml (25 °C)
100 g/100 ml (100 °C)
Solubility Reacts with bases
Insoluble in ammonia, ethanol, pyridine, toluene, xylene
Acidity (pKa) 1.99
Safety data sheet Sigma-Aldrich
Flash point Non-flammable
Lethal dose or concentration (LD, LC):
2,490 mg/kg (rat, oral)
Related compounds
Related compounds
Sodium sulfate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Sodium bisulfate, also known as sodium hydrogen sulfate, is the sodium salt of the bisulfate anion, with the molecular formula NaHSO4. It is an acid salt, formed by the partial neutralization of sulfuric acid with an equivalent of sodium, usually sodium chloride or sodium hydroxide.



Sodium bisulfate will react with sodium chloride to release hydrogen chloride. Heat accelerates the reaction.

NaHSO4 + NaCl → Na2SO4 + HCl

Sodium bisulfate is an acid salt. Heating (and even just sitting) can release sulfuric acid vapors, from small amounts to large quantities of fumes.


Sodium bisulfate is a white dry granular product, soluble in water and acids. The anhydrous form is hygroscopic. Solutions of sodium bisulfate are acidic, 1 M solution having a pH of < 1.


Sodium bisulfate is available as a pH lowering chemical for swimming pools in most hardware stores and it's fairly pure.


Sodium bisulfate is made by mixing stoichiometric quantities of sodium hydroxide or sodium chloride and sulfuric acid.

NaOH + H2SO4 → NaHSO4 + H2O
NaCl + H2SO4 → NaHSO4 + HCl




Sodium bisulfate will irritate the skin, eyes and mucous tissues on contact. Despite being a salt rather than a fully saturated acid, sodium bisulfate solutions have a much lower pH than many acids themselves, and should be treated with care. Prolonged exposure will damage the tissues.[3] Do not attempt to smell sodium bisulfate. It is common for a sample to release sulfuric acid vapors, and these can build up in a container.[4]


Sodium bisulfate should be stored in closed bottles. You should open them periodically outside to release any acidic vapors inside.


Sodium bisulfate is not very dangerous to the environment in small quantities, though it should be neutralized first before disposal. A base like sodium carbonate or bicarbonate in aqueous solution can be used. While you can pour it down the drain, avoid dumping it in the ground, as the sodium ions are harmful to plants.


  4. "The Volatile Chemist's" personal experience

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