Potassium bisulfate

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Potassium bisulfate
One potassium cation and one hydrogensulfate anion
Ball-and-stick model of the component ions
IUPAC name
Potassium hydrogen sulfate
Other names
Potassium acid sulfate
7646-93-7 YesY
EC number 231-594-1
Jmol-3D images Image
PubChem 516920
RTECS number TS7200000
UN number 2509
Molar mass 136.169 g/mol
Appearance colorless solid
Odor odorless
Density 2.245 g/cm3
Melting point 197 °C (387 °F; 470 K)
Boiling point 300 °C (572 °F; 573 K) (decomposes)
36.6 g/100 mL (0 °C)
49 g/100 mL (20 °C)
121.6 g/100 mL (100 °C)
Solubility soluble in acetone, ethanol.
-1163.3 kJ/mol
Safety data sheet External MSDS
EU classification Corrosive (C)
R-phrases R34, R36, R37, R38
S-phrases (S1/2), S26, S36/37/39, S45
Lethal dose or concentration (LD, LC):
2340 mg*kg−1
Related compounds
Related compounds
Sodium bisulfate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Potassium bisulfate is a potassium acid salt of sulfuric acid, with the molecular formula KHSO
. This compound is commonly used in the conversion of tartrates to bitartrates in wine. Potassium bisulfate is also used as a disintegrating agent in analytical chemistry.

A solution of potassium bisulfate behaves as if the two related compounds (K
and H
) were side by side uncombined. Adding ethanol to a solution of potassium bisulfate precipitates out sulfate.

Mercallite, the mineralogical form of potassium bisulfate, occurs very rarely. Misenite is the other, more complex, potassium hydrogen sulfate.


Potassium bisulfate is prepared by the reaction between sulfuric acid and potassium carbonate. Carbon dioxide gas is produced as a by-product. Potassium bisulfate is also the main by-product of the production of nitric acid by the distillation of potassium nitrate and sulfuric acid.

Chemical Properties[edit]

  • Potassium bisulfate can be used to prepare potassium persulfate by electrolysis of saturated aqueous KHSO4 at 0-8 °C. The product, having the limited solubility in water, precipitates from the reaction mixture as white crystals.
2 KHSO4 → K2S2O8 + H2


  • O'Neil, Maryadele J., ed. (2006). Merck Index of Chemicals and Drugs (14th ed.). Whitehouse Station, NJ: Merck. ISBN 978-0-911910-00-1.