Description
▶Sodium acetate (CH3COONa) is the sodium salt of acetic acid. It appears as a colorless deliquescent salt with a wide range of applications. In industry, it can be used in textile industry to neutralize sulfuric acid waste streams and as a photoresist upon using aniline dyes. In concrete industry, it can be used as a concrete sealant to mitigate the water damage. In food, it can be used as a seasoning. It can also be used as a buffer solution in lab. In addition, it is also used in heating pads, hand warmers and hot ice. For laboratory use, it can be produced by the reaction between acetate with the sodium carbonate, sodium bicarbonate and sodium hydroxide. In industry, it is prepared from the glacial acetic acid and sodium hydroxide.
▶Chemical Properties
Anhydrous salt is a colorless crystalline solid; density 1.528 g/cm3; melts at 324°C; very soluble in water; moderately soluble in ethanol. The colorless crystalline trihydrate has a density 1.45 g/cm3; decomposes at 58°C; is very soluble in water; pH of 0.1M aqueous solution is 8.9; moderately soluble in ethanol, 5.3 g/100mL.
▶Storage and Transport
It should be stored in a dry and ventilative warehouse, kept away from heat and moisture during transportation, unloaded with care so as to avoid damage. Furthermore, it must be stored separately from poisonous substances.
Application
▶Industrial
Sodium acetate is used in the textile industry to neutralize sulfuric acid waste streams and also as a photoresist while using aniline dyes. It is also a pickling agent in chrome tanning and helps to impede vulcanization of chloroprene in synthetic rubber production. In processing cotton for disposable cotton pads, sodium acetate is used to eliminate the buildup of static electricity. It is also used as “hot-ice” in hand warmer.
▶Concrete longevity
Sodium acetate is used to mitigate water damage to concrete by acting as a concrete sealant, while also being environmentally benign and cheaper than the commonly used epoxy alternative for sealing concrete against water permeation.
▶Buffer solution
As the conjugate base of acetic acid, a solution of sodium acetate and acetic acid can act as a buffer to keep a relatively constant pH level. This is useful especially in biochemical applications where reactions are pH-dependent in a mildly acidic range (pH 4-6). It is also used in consumer HEATING PADS or hand warmers and is also used in hot ice.Sodium acetate trihydrate crystals melt at 58 °C, dissolving in their water of crystallization. When they are heated to around 100°C, and subsequently allowed to cool, the aqueous solution becomes supersaturated. This solution is capable of super cooling to room temperature without forming crystals. By clicking on a metal disc in the heating pad, a nucleation center is formed which causes the solution to crystallize into solid trihydrate crystals again. The bond-forming process of crystallization is exothermic, hence heat is emitted. The latent heat of fusion is about 264–289 kJ/kg.