What Is Sodium Dihydrogen Phosphate?
Sodium dihydrogen phosphate, also known as monosodium phosphate, monosodium monophosphate, or monosodium soda, is an inorganic compound with the chemical formula NaH2PO4. It exists in several forms, including anhydrous, monohydrate, and dihydrate.
Uses of Sodium Dihydrogen Phosphate
This compound finds extensive use in the food industry as a food additive, and in applications such as baking powder, emulsifiers, meat binders, buffers, pH adjusters, detergents, canning agents, in cell culture, and as a dyeing aid. Additionally, it serves as a laboratory pH buffer due to its solubility and buffering capability in water. In medicine, it is prescribed to increase blood phosphorus levels and is used in a laxative mixture with sodium bicarbonate.
Properties of Sodium Dihydrogen Phosphate
Sodium dihydrogen phosphate appears as a white crystal or powder and is hygroscopic. It has a molecular weight of 119.98, a density of 2.36 g/mL for the anhydrous form, and a solubility of 59.90 g/100 mL in water at 0°C. The pH of a 0.2 mol/L aqueous solution is between 4.2 and 4.7 at 25°C. It is almost insoluble in ethanol.
Types of Sodium Dihydrogen Phosphate
Available as both a research reagent and an industrial chemical, it comes in various forms and volumes to suit different applications, including anhydrous, monohydrate, and dihydrate.
1. Reagent Products for Research and Development
These products are available in forms such as anhydrous, monohydrate, and dihydrate, with volumes ranging from 25g to 500g, depending on the manufacturer. They can be stored at room temperature.
2. Industrial Chemicals
As an industrial chemical, it is sold in forms like anhydrous and dihydrate, primarily used as a food additive and in general industrial applications, typically in larger volumes like 25 kg.
Other Information on Sodium Dihydrogen Phosphate
1. Synthesis of Sodium Dihydrogen Phosphate
It is commonly produced by the partial neutralization of phosphoric acid using sodium hydroxide.
2. Chemical Reaction of Sodium Dihydrogen Phosphate
Upon heating to 169 ºC, it decomposes to disodium dihydrogen phosphate and water. At 550 ºC, it further decomposes to sodium trimetaphosphate and water. It is stable under normal conditions but hygroscopic, requiring storage away from heat, sunlight, and moisture.
3. Hazard and Regulatory Information
Classified as a Class 2B irritant by the GHS for serious eye damage/irritation, handling precautions include wearing personal protective equipment and avoiding contact with skin and eyes. It is not regulated by major industrial and safety laws but requires careful handling and storage.