Monopotassium phosphate

Monopotassium phosphate

Two unit cells of MKP viewed close to the b axis
Names
IUPAC names
Potassium dihydrogen phosphate[1]
Other names
Potassium phosphate monobasic;
Phosphoric acid, monopotassium salt;
Potassium biphosphate
Identifiers
3D model (JSmol)
ChEMBL
ChemSpider
ECHA InfoCard 100.029.012 Edit this at Wikidata
EC Number
  • 231-913-4
E number E340(i) (antioxidants, ...)
RTECS number
  • TC6615500
UNII
  • InChI=1S/3K.H3O4P/c;;;1-5(2,3)4/h;;;(H3,1,2,3,4)/q3*+1;/p-3 checkY
    Key: LWIHDJKSTIGBAC-UHFFFAOYSA-K checkY
  • InChI=1/3K.H3O4P/c;;;1-5(2,3)4/h;;;(H3,1,2,3,4)/q3*+1;/p-3
    Key: LWIHDJKSTIGBAC-DFZHHIFOAX
  • [K+].OP(O)([O-])=O
Properties
KH
2PO
4
Molar mass 136.086 g/mol
Appearance Colourless crystals or white granular or crystalline powder[2]
Odor Odorless [2]
Density 2.338 g/cm3
Melting point 252.6 °C (486.7 °F; 525.8 K) [4]
Boiling point 400 °C (752 °F; 673 K) , decomposes
22.6 g/100 mL (20 °C)
83.5 g/100 mL (90 °C)
Solubility Slightly soluble in ethanol
Acidity (pKa) 6.86[3]
Basicity (pKb) 11.9
1.4864
Structure
Tetragonal[5]
I42d
a = 0.744 nm, b = 0.744 nm, c = 0.697 nm
Hazards
GHS labelling:
GHS07: Exclamation mark[6]
Warning[6]
H315, H319[6]
P264, P280, P305+P351+P338, P321, P332+P313, P337+P313[6]
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
1
0
0
Flash point Non-flammable
Lethal dose or concentration (LD, LC):
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).
☒N verify (what is checkY☒N ?)

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.[7]

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

  1. ^ "Potassium dihydrogen phosphate".
  2. ^ a b "Commission Regulation (EU) No 231/2012 of 9 March 2012 laying down specifications for food additives listed in Annexes II and III to Regulation (EC) No 1333/2008 of the European Parliament and of the Council Text with EEA relevance". EUR-Lex. E 340 (i) MONOPOTASSIUM PHOSPHATE. Retrieved 19 January 2023.{{cite web}}: CS1 maint: location (link)
  3. ^ Mathews, Christopher K., K. E. Van Holde, Ean R. Appling, and Spencer J. Anthony-Cahill. Biochemistry. Redwood City, CA: Benjamin/Cummings Pub., 1990. Print.
  4. ^ King, Harold S. J. Am. Chem. Soc. 1927, 49, 6, 1511–1512 https://doi.org/10.1021/ja01405a018
  5. ^ Ono, Yasuhiro; Hikita, Tomoyuki; Ikeda, Takuro (1987). "Phase Transitions in Mixed Crystal System K1−x(NH4)xH2PO4". Journal of the Physical Society of Japan. 56 (2): 577. Bibcode:1987JPSJ...56..577O. doi:10.1143/JPSJ.56.577.
  6. ^ a b c d "Potassium Dihydrogen Phosphate". American Elements. Retrieved October 30, 2018.
  7. ^ Klaus Schrödter; Gerhard Bettermann; Thomas Staffel; Friedrich Wahl; Thomas Klein; Thomas Hofmann (2012). "Phosphoric Acid and Phosphates". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a19_465.pub3. ISBN 978-3527306732.