Na2HPO47H2O

Disodium hydrogen phosphate heptahydrate, with the chemical formula Na2HPO4·7H2O, is a salt of phosphoric acid. It is a crystalline solid that is soluble in water and slightly soluble in ethanol. This compound is also known by several other names including disodium phosphate heptahydrate, sodium phosphate dibasic heptahydrate, and sodium hydrogen phosphate heptahydrate.

Na2HPO4·7H2O is typically a white or colorless crystalline substance. It is hygroscopic, meaning it tends to absorb moisture from the air. When heated, it loses its water of hydration and transforms into other forms of disodium hydrogen phosphate, eventually becoming anhydrous disodium hydrogen phosphate.

In industrial applications, disodium hydrogen phosphate heptahydrate is used in various processes. It serves as a buffering agent in many chemical and biological systems due to its ability to maintain a relatively stable pH. It is also employed as a food additive, commonly designated as E339(ii), where it functions as an acidity regulator, emulsifier, and texturizer. Furthermore, it finds use in water treatment to prevent corrosion and in the textile industry as a dyeing auxiliary. Its pharmaceutical applications include use in laxatives and as an ingredient in certain formulations.