Sodium Phosphate, Dibasic → Phosphoric Acid

Participants

Reaction Steps

Disodium hydrogenphosphate (secondary sodium phosphate), Na2HPO4, is a colorless, water-soluble crystalline salt. It exists anyhdrously and with 2 mol (density 2.066 gcm−3, water lost at 95°), 7 mol (density 1.68 gcm−3, melting point 48° with loss of 5 H2O), and 12 mol of water (density 1.52 gcm−3, melting point 35° with loss of 5 H2O); it becomes anhydrous at 100° and when more strongly heated transitions into the diphosphate Na4P2O7. Disodium hydrogenphosphate is produced by the neutralization of phosphoric acid with a soda solution using phenolphthalein as indicator. Dipotassium hydrogenphosphate (secondary or dibasic potassium phosphate), K2HPO4, is an amorphous white salt that is easily soluble in water.

Provenance & Evidence