Monopotassium phosphate
Two unit cells of MKP viewed close to the b axis
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Names | |
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IUPAC names
Potassium dihydrogen phosphate[1]
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Other names
Potassium phosphate monobasic;
Phosphoric acid, monopotassium salt; Potassium biphosphate | |
Identifiers | |
3D model (
JSmol ) |
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ChEMBL | |
ChemSpider | |
ECHA InfoCard
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100.029.012 |
EC Number |
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E number | E340(i) (antioxidants, ...) |
PubChem CID
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RTECS number
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UNII | |
CompTox Dashboard (EPA)
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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 |
Refractive index (nD)
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1.4864 |
Structure | |
Tetragonal[5] | |
I42d | |
a = 0.744 nm, b = 0.744 nm, c = 0.697 nm
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Hazards | |
GHS labelling: | |
[6] | |
Warning[6] | |
H315, H319[6] | |
P264, P280, P305+P351+P338, P321, P332+P313, P337+P313[6] | |
NFPA 704 (fire diamond) | |
Flash point | Non-flammable |
Lethal dose or concentration (LD, LC): | |
LD50 (median dose)
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3200 mg/kg (rat, oral) |
Safety data sheet (SDS) | External MSDS |
Related compounds | |
Other cations
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Monoammonium phosphate
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Related compounds
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Dipotassium phosphate Tripotassium phosphate |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Monopotassium phosphate (MKP) (also, potassium dihydrogen phosphate, KDP, or monobasic potassium phosphate) is the
buffering agent. The salt often cocrystallizes with the dipotassium salt as well as with phosphoric acid.[7]
ferroelectric
.
Structure
Monopotassium phosphate can exist in several
ferroelectric phase of orthorhombic symmetry, and the transition temperature shifts up to −50 °C (−58 °F) when hydrogen is replaced by deuterium.[8] Heating to 190 °C (374 °F) changes its structure to monoclinic.[9]
When heated further, MKP decomposes, by loss of water, to potassium metaphosphate, KPO3, at 400 °C (752 °F).
Symmetry | Space group |
№ | Pearson symbol |
a (nm) |
b (nm) |
c (nm) |
Z | Density (g/cm3) |
T (°C, °F, K) |
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Orthorhombic[8]
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Fdd2 | 43 | oF48 | 1.0467 | 1.0533 | 0.6926 | 8 | 2.37 | < −150 °C, −238 °F, 123 K |
Tetragonal[5]
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I42d | 122 | tI24 | 0.744 | 0.744 | 0.697 | 4 | 2.34 | −150 to 190 °C, −238 to 374 °F, 123 to 463 K |
Monoclinic[9]
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P21/c | 14 | mP48 | 0.733 | 1.449 | 0.747 | 8 | 190 to 400 °C, 374 to 752 °F, 463 to 673 K |
Manufacturing
Monopotassium phosphate is produced by the action of phosphoric acid on potassium carbonate.
Applications
Fertilizer-grade MKP powder contains the equivalent of 52% P
2O
5 and 34% K
2O, and is labeled
NPK 0-52-34. MKP powder is often used as a nutrient source in the greenhouse trade and in hydroponics
.
As a
non-linear optics such as second-harmonic generation
(SHG).
Also, to be noted is KD*P,
neodymium-based lasers
. Regular KDP has absorbances at this wavelength of approximately 4.7–6.3% per cm of thickness while highly deuterated KDP has absorbances of typically less than 0.8% per cm.
Monopotassium phosphate is also used as an ingredient in sports drinks such as Gatorade and Powerade.
In medicine, monopotassium phosphate is used for phosphate substitution in hypophosphatemia.[10]
Gallery
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A large KDP crystal, used in the form of slices at the National Ignition Facility
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Alternate angle, covered
References
- ^ "Potassium dihydrogen phosphate".
- ^ 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) - ^ Mathews, Christopher K., K. E. Van Holde, Ean R. Appling, and Spencer J. Anthony-Cahill. Biochemistry. Redwood City, CA: Benjamin/Cummings Pub., 1990. Print.
- ^ King, Harold S. J. Am. Chem. Soc. 1927, 49, 6, 1511–1512 https://doi.org/10.1021/ja01405a018
- ^ .
- ^ a b c d "Potassium Dihydrogen Phosphate". American Elements. Retrieved October 30, 2018.
- ISBN 978-3527306732.
- ^ .
- ^ .
- PMID 16194637.
External links
Wikimedia Commons has media related to Monopotassium phosphate.