What Is Sodium Phosphate?
Sodium phosphate, predominantly known as trisodium phosphate (Na3PO4), is a compound also referred to as sodium orthophosphate. It appears as a white, odorless crystal with a molecular weight of 163.94 and a CAS number of 7601-54-9. Disodium hydrogen phosphate (Na2HPO4) is another form often called sodium phosphate in pharmaceutical and industrial contexts.
Uses of Sodium Phosphate
1. Food Industry
Used as a binding agent in meats and as a pH adjuster and brine additive, enhancing texture and flavor.
2. Industrial Applications
Employed in photography, paper manufacturing, tanning, dyeing, and as an ingredient in pharmaceuticals, detergents, and plant disease disinfectants.
Properties of Sodium Phosphate
Sodium phosphate is highly soluble in water, with a solubility of 14.5g per 100g water at 25°C, and forms strongly alkaline solutions. It has a density of 2.5 g/cm3 and a high melting point of 1340°C. Upon heating, it decomposes, emitting toxic fumes and is insoluble in ethanol.
Types of Sodium Phosphate
It exists in various forms, including anhydrous, monohydrate, hexahydrate, heptahydrate, decahydrate, and dodecahydrate, with the anhydrous, hexahydrate, and dodecahydrate forms being the most commercially prevalent.
Other Information on Sodium Phosphate
1. Synthesis of Sodium Phosphate
Sodium phosphate can be synthesized from the reaction of phosphoric acid with sodium hydroxide, yielding various hydrates under different conditions. It also reacts with hydrogen chloride and perchloric acid, forming by-products like sodium chloride and sodium perchlorate.
2. Neutralization Titration and Buffering of Aqueous Phosphoric Acid Solutions
The neutralization titration of sodium phosphate with sodium hydroxide involves a three-step reaction process, showcasing its buffering capabilities in solutions above pH 11.