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Sodium bisulfate

Sodium bisulfate
Systematic name sodium hydrogen sulfate
Other names sodium bisulfate
sodium acid sulfate
Molecular formula NaHSO4
Molar mass 120.06 g/mol (anhydrous)
138.07 g/mol (monohydrate)
Appearance white solid
CAS number [7681-38-1]
Density 2.742 g/cm3 (anhydrous)
Solubility (water)

50 g / 100 ml (0°C) (of anhydrous)
100 g / 100ml (100°C) (of anhydrous)

Melting point 58.5°C (monohydrate)
>315°C (anhydrous) w some decomp
Boiling point decomposes to Na2S2O7
pKa (25°C) 1.9
Crystal structure triclinic (anhydrous)
monoclinic (monohydrate)
Except where noted otherwise, data are given for
materials in their standard state (at 25 °C, 100 kPa)
Infobox disclaimer and references

Sodium bisulfate, also sodium hydrogen sulfate, has the chemical formula NaHSO4.



Sodium bisulfate is produced by two methods. One method involves mixing stoichiometric quantities of sodium hydroxide and sulfuric acid which react to form sodium bisulfate and water.

NaOH + H2SO4 → NaHSO4 + H2O

A second production method involves reacting sodium chloride (salt) and sulfuric acid at elevated temperatures to produce sodium bisulfate and hydrogen chloride gas.

NaCl + H2SO4 → NaHSO4 + HCl

The liquid sodium bisulfate is sprayed and cooled so that it forms a solid bead. The hydrogen chloride gas is dissolved in water to produce hydrochloric acid as a useful byproduct of the reaction.

Descriptive Chemistry

The product of commerce is anhydrous. The only producer in the USA, Jones Hamilton Company, uses the Sulfuric Acid/Sodium Chloride process, which produces anhydrous product.

Solutions of sodium bisulfate are acid, with a 1M solution having pH of 1.4. In some applications, such solutions can be used instead of sulfuric acid solution. For example, from a solution of sodium bisulfate and sodium acetate it is possible to distill acetic acid. Sodium bisulfate solutions will also liberate CO2 from most carbonates.

The anhydrous form is hygroscopic. Its melting point is poorly defined because it begins to decompose into sodium pyrosulfate and water before it reaches its melting points.

Sodium bisulfate behaves, to some degree, as if it were a complex of sodium sulfate with sulfuric acid. This is evident if either the anhydrous form or the monohydrate come in contact with ethanol, which causes them to separate into those two components. [1]


  • Household cleaners, Sani-Flush, for example (roughly 45%)
  • Silver pickling
  • To reduce alkalinity and pH in swimming pools
  • In pet foods[1]
  • As a preservative for soil samples in analytical laboratory analysis


  1. ^ Merck Index of Chemicals and Drugs, 9th ed. monograph 8330
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Sodium_bisulfate". A list of authors is available in Wikipedia.
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