What are the chemical and physical properties of HEDP?

Hydroxyethylidene diphosphonic acid (HEDP) is a phosphonic acid that has a molecular formula of C2H8O7P2. Here are some of its chemical and physical properties:

Chemical Properties:

HEDP is an organic phosphonic acid with two phosphonic acid groups and a hydroxyethyl group.
It has a pKa value of 2.02 for the first proton and 7.20 for the second proton.
HEDP exhibits good thermal stability and is stable under normal conditions.
Physical Properties:

HEDP is a colorless or pale yellow liquid with a mild odor.
It has a density of 1.43 g/cm³ at 20°C.
HEDP is highly soluble in water, and its solubility increases with temperature.
It has a melting point of -43°C and a boiling point of 230°C at 760 mmHg.
HEDP is hygroscopic, meaning it readily absorbs moisture from the air.
Overall, HEDP exhibits good chemical and physical stability, making it a useful compound in various applications, especially in water treatment. Its ability to chelate metal ions and prevent the formation of scale and deposits make it an effective sequestrant in cooling water and boiler water systems.