Potassium hydrogen sulfate

Potassium bisulfate

Names
IUPAC name Potassium hydrogen sulfate
Other names Potassium acid sulfate
Identifiers
CAS Number	7646-93-7 Y
3D model (Jmol)	Interactive image
ChemSpider	56396 N
ECHA InfoCard	100.028.722
EC Number	231-594-1
PubChem CID	516920
RTECS number	TS7200000
UN number	2509
InChI InChI=1S/K.H2O4S/c;1-5(2,3)4/h;(H2,1,2,3,4)/q+1;/p-1 N Key: CHKVPAROMQMJNQ-UHFFFAOYSA-M N InChI=1/K.H2O4S/c;1-5(2,3)4/h;(H2,1,2,3,4)/q+1;/p-1 Key: CHKVPAROMQMJNQ-REWHXWOFAH
SMILES OS(=O)(=O)[O-].[K+]
Properties
Chemical formula	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)
Solubility in water	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.
Magnetic susceptibility (χ)	−49.8·10−6 cm3/mol
Thermochemistry
Std enthalpy of formation (ΔfHo298)	-1163.3 kJ/mol
Hazards
Safety data sheet	External MSDS
EU classification (DSD) (outdated)	Corrosive (C)
R-phrases (outdated)	R34, R36, R37, R38
S-phrases (outdated)	(S1/2), S26, S36/37/39, S45
Lethal dose or concentration (LD, LC):
LD50 (median dose)	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).
N  (what is YN ?)
Infobox references

Potassium bisulfate is an inorganic compound with the chemical formula KHSO₄ and is the potassium acid salt of sulfuric acid.

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

Potassium bisulfate is prepared by neutralizing sulfuric acid with an equal molar amount of a potassium containing base, for example potassium hydroxide:

Potassium bisulfate is also formed by the union of sulfuric acid with potassium sulfate:

Potassium bisulfate is also the main by-product in the production of nitric acid from potassium nitrate and sulfuric acid:

Thermal decomposition of potassium bisulfate forms potassium pyrosulfate and water:

Temperatures above 600 °C further decompose potassium bisulfate to potassium sulfate and sulfur trioxide:

Aqueous solutions of potassium bisulfate behave as two separate, uncombined compounds, K₂SO₄ and H₂SO₄. Adding ethanol to the solution precipitates out potassium sulfate.

Potassium bisulfate is commonly used to prepare potassium bitartrate for winemaking. Potassium bisulfate is also used as a disintegrating agent in analytical chemistry or as a precursor to prepare potassium persulfate, a powerful oxidizing agent.