Potassium bisulfate

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
CAS Number	7646-93-7 Y
ChemSpider	56396
EC Number	231-594-1
Jmol 3D model	Interactive image
PubChem	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 Key: CHKVPAROMQMJNQ-UHFFFAOYSA-M 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.
Thermochemistry
Std enthalpy of formation (ΔfHo298)	-1163.3 kJ/mol
Vapor pressure	{{{value}}}
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).
Y verify (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.

Natural Occurrence

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

Preparation

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

H₂SO₄ + KOH → KHSO₄ + H₂O

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

H₂SO₄ + K₂SO₄ → 2 KHSO₄

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

KNO₃ + H₂SO₄ → KHSO₄ + HNO₃

Chemical Properties

Thermal decomposition of potassium bisulfate forms potassium pyrosulfate and water:

2 KHSO₄ → K₂S₂O₇ + H₂O

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

KHSO₄ → K₂SO₄ + SO₃ + H₂O

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

Uses

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.

See Also

• Sodium bisulfate

References

Salts and the ester of the sulfate ion
H2SO4																	He
Li2SO4	BeSO4											B	(RO)2SO3	(NH4)2SO4 N2H6SO4 (NH3OH)2SO4	O	F	Ne
Na2SO4 NaHSO4	MgSO4											Al2(SO4)3	Si	P	SO42−	Cl	Ar
K2SO4 KHSO4	CaSO4	Sc2(SO4)3	Ti(SO4)2 TiOSO4	V2(SO4)3 VOSO4	CrSO4 Cr2(SO4)3	MnSO4	FeSO4 Fe2(SO4)3	CoSO4, Co2(SO4)3	NiSO4	CuSO4	ZnSO4	Ga2(SO4)3	Ge	As	Se	Br	Kr
Rb2SO4	SrSO4	Y2(SO4)3	Zr(SO4)2	Nb	Mo	Tc	Ru	Rh	PdSO4	Ag2SO4	CdSO4	In2(SO4)3	SnSO4	Sb2(SO4)3	Te	I	Xe
Cs2SO4	BaSO4		Hf	Ta	W	Re	Os	Ir	Pt	Au	Hg2SO4, HgSO4	Tl2SO4	PbSO4	Bi2(SO4)3	Po	At	Rn
Fr	Ra		Rf	Db	Sg	Bh	Hs	Mt	Ds	Rg	Cn	Uut	Fl	Uup	Lv	Uus	Uuo
		↓
		La	Ce2(SO4)3 Ce(SO4)2	Pr2(SO4)3	Nd	Pm	Sm	Eu	Gd	Tb	Dy	Ho	Er	Tm	Yb2(SO4)3	Lu
		Ac	Th	Pa	U(SO4)2 UO2SO4	Np	Pu	Am	Cm	Bk	Cf	Es	Fm	Md	No	Lr