Molar mass 119.98 g/mol Soluble in Water | Formula NaH2PO4 Appearance White powder or crystals | |
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Related compounds IUPAC ID Sodium dihydrogen phosphate | ||
Monosodium phosphate
Monosodium phosphate (MSP), also known as anhydrous monobasic sodium phosphate and sodium dihydrogen phosphate, is an inorganic compound of sodium with dihydrogen phosphate (H2PO4−) anion. One of many sodium phosphates (such as NaPO3), it is a common industrial chemical. It exists as an anhydrous salt, as well as mono- and dihydrates.
Contents
Monosodium phosphate
Production and reactions
The salt is obtained by partial neutralization of phosphoric acid. The pKa of monosodium phosphate is 6.8-7.2 (depending on the physicochemical characteristics during pKa determination).
Heating this salt above 169 °C gives the corresponding sodium acid pyrophosphate:
2 NaH2PO4 → Na2H2P2O7 + H2OUses
Phosphates are often used in foods and in water treatment. The pH of such formulations is generally adjusted by mixtures of various sodium phosphates, such as this salt. The sodium chloride equivalent value, or E-Value, is 0.49. It is soluble in 4.5 parts water.
Food additive
It is added in animal feed, toothpaste, and evaporated milk. It is used as a thickening agent and emulsifier.
Detection of magnesium
Monosodium phosphate is used to detect the presence of magnesium ions in salts. Formation of a white precipitate on the addition of ammonium chloride, ammonium hydroxide and monosodium phosphate to an aqueous or dilute HCl solution of the salt indicates presence of magnesium ions.