Dipotassium phosphate

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Dipotassium phosphate
Dipotassium phosphate bottle sample.jpg
Dipotassium phosphate sample and original bottle
Names
IUPAC names
Potassium hydrogenphosphate
Potassium hydroxidotrioxidophosphate(2−)
Systematic IUPAC name
Potassium hydroxidotrioxidophosphate(2−)
Other names
Dipotassium hydrogen orthophosphate
Dipotassium hydrogen phosphate
Dipotassium hydrogenphosphate
Dipotassium monohydrogen phosphate
Phosphoric acid dipotassium salt
Potassium phosphate dibasic
Potassium monohydrogen phosphate
Properties
K2HPO4
Molar mass 174.2 g/mol
Appearance White solid
Odor Odorless
Density 2.44 g/cm3
Melting point 465 °C (869 °F; 738 K) (decomposes)
Boiling point Decomposes
149.25 g/100 ml (20 °C)
Solubility Slightly soluble in ethanol, methanol
Insoluble in ethers, hydrocarbons, halocarbons
Vapor pressure ~0 mmHg
Acidity (pKa) 12.4
Hazards
Safety data sheet Sigma-Aldrich
Flash point Non-flammable
Related compounds
Related compounds
Monopotassium phosphate
Tripotassium phosphate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Dipotassium phosphate, also called potassium hydrogen phosphate or potassium phosphate dibasic, is one of the potassium salts of phosphoric acid, with the formula K2HPO4.

Properties

Chemical

Dipotassium phosphate can be converted to tripotassium phosphate by reacting with an equimolar amount of potassium hydroxide.

Physical

Dipotassium phosphate is a colorless crystalline solid, soluble in water, but less so in alcohols. It is odorless.

Availability

Dipotassium phosphate is sold in agricultural stores as fertilizer.

Can also be purchased from chemical suppliers.

Preparation

Can be prepared by adding potassium hydroxide to phosphoric acid in a 2:1 molar ratio, or to monopotassium phosphate in a 1:1 molar ratio:

2 KOH + H3PO4 → K2HPO4 + H2O
KOH + KH2PO4 → K2HPO4 + H2O

Projects

  • Buffering agent
  • Make tripotassium phosphate
  • Fertilizer

Handling

Safety

Dipotassium phosphate has low toxicity and doesn't require special handling.

Storage

Potassium phosphate dibasic should be kept in closed bottles.

Disposal

No special disposal is required, discard it as you wish.

References

Relevant Sciencemadness threads