Potassium bisulfate

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Potassium bisulfate
One potassium cation and one hydrogensulfate anion
Ball-and-stick model of the component ions
Names
IUPAC name
Potassium hydrogen sulfate
Other names
Potassium acid sulfate
Identifiers
7646-93-7 YesY
EC number 231-594-1
Jmol-3D images Image
PubChem 516920
RTECS number TS7200000
UN number 2509
Properties
KHSO4
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.
Thermochemistry
-1163.3 kJ/mol
Hazards
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
4
. 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
2
SO
4
and H
2
SO
4
) 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.

Preparation[edit]

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


References[edit]

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