Monopotassium phosphate

Monopotassium phosphate
	Two unit cells of MKP viewed close to the b axis
Names
	IUPAC names Potassium dihydrogen phosphate
	Other names Potassium phosphate monobasic;; Phosphoric acid, monopotassium salt; ; Potassium biphosphate
Identifiers
CAS Number	7778-77-0 ;
3D model (JSmol)	Interactive image;
ChEMBL	ChEMBL1200925 ;
ChemSpider	22914 ;
ECHA InfoCard	100.029.012
EC Number	231-913-4;
E number	E340(i) (antioxidants, ...)
PubChem CID	516951;
RTECS number	TC6615500;
UNII	4J9FJ0HL51 ;
CompTox Dashboard (EPA)	DTXSID0035667 ;
	InChI InChI=1S/3K.H3O4P/c;;;1-5(2,3)4/h;;;(H3,1,2,3,4)/q3+1;/p-3 Key: LWIHDJKSTIGBAC-UHFFFAOYSA-K ; InChI=1/3K.H3O4P/c;;;1-5(2,3)4/h;;;(H3,1,2,3,4)/q3+1;/p-3 Key: LWIHDJKSTIGBAC-DFZHHIFOAX;
	SMILES [K+].OP(O)([O-])=O;
Properties
Chemical formula	KH; 2PO; 4
Molar mass	136.086 g/mol
Appearance	Colourless crystals or white granular or crystalline powder
Odor	Odorless
Density	2.338 g/cm3
Melting point	252.6 °C (486.7 °F; 525.8 K)
Boiling point	400 °C (752 °F; 673 K) , decomposes
Solubility in water	22.6 g/100 mL (20 °C); 83.5 g/100 mL (90 °C)
Solubility	Slightly soluble in ethanol
Acidity (pKa)	6.86
Basicity (pKb)	11.9
Refractive index (nD)	1.4864
Structure
Crystal structure	Tetragonal
Space group	I42d
Lattice constant	a = 0.744 nm, b = 0.744 nm, c = 0.697 nm
Hazards
	GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H315, H319
Precautionary statements	P264, P280, P305+P351+P338, P321, P332+P313, P337+P313
NFPA 704 (fire diamond)	1 0 0
Flash point	Non-flammable
	Lethal dose or concentration (LD, LC):
LD50 (median dose)	3200 mg/kg (rat, oral)
Safety data sheet (SDS)	External MSDS
Related compounds
Other cations	Monosodium phosphate; Monoammonium phosphate
Related compounds	Dipotassium phosphate; Tripotassium phosphate
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Monopotassium phosphate (MKP) (also, potassium dihydrogen phosphate, KDP, or monobasic potassium phosphate) is the inorganic compound with the formula KH₂PO₄. Together with dipotassium phosphate (K₂HPO₄^.(H₂O)_x) it is often used as a fertilizer, food additive, and buffering agent. The salt often cocrystallizes with the dipotassium salt as well as with phosphoric acid.

Single crystals are paraelectric at room temperature. At temperatures below −150 °C (−238 °F), they become ferroelectric.