What Is Sodium Acetate?
Sodium acetate is a compound formed from acetate and sodium ions.
It is produced by the neutralization reaction of acetic acid with sodium hydroxide. Known also by its chemical formula, CH3COONa, sodium acetate has a molecular weight of 82.03. It exists in both anhydrous and trihydrate forms, both of which are white, crystalline substances at room temperature, and highly soluble in water.
Sodium acetate acts as a flame retardant and is considered a safe substance, commonly used as a food additive.
Uses of Sodium Acetate
Sodium acetate has various applications:
1. Reagent
As a reagent, sodium acetate is used to create buffer solutions that maintain a constant pH level, even when small amounts of acid or base are added. These buffer solutions are employed in HPLC (high-performance liquid chromatography) analyses.
2. Food Additive
As a food additive, sodium acetate helps extend the shelf life of food products by inhibiting the growth of microorganisms. It’s also used to adjust the acidity of sauces and mayonnaise.
3. Mordant
Sodium acetate enhances the adhesion of dyes to fabrics. For instance, adding sodium acetate to persimmon tannin dye improves its binding to linen.
Additionally, sodium acetate finds use in pharmaceuticals, photographic chemicals, plating agents, dehydrating agents, and as a catalyst in organic synthesis.
Properties of Sodium Acetate
Sodium acetate, a salt of acetic acid (a weak acid) and sodium hydroxide (a strong base), dissociates in water into acetate (CH3COO–) and sodium ions (Na+).
CH3COONa → CH3COO– + Na+
In aqueous solutions, acetate ions often react with hydrogen ions to form acetic acid molecules, leading to a slightly basic solution (pH 7 to 9). Sodium acetate’s solubility in water at 20°C is 46.4 grams per 100 grams of water, indicating it should be stored in a dry environment to maintain its stability.
Types of Sodium Acetate
Sodium acetate is available in various grades for different applications, including pharmaceutical testing, food additives, reagent special grade, and industrial use, with quantities ranging from 25 grams to 20 kilograms. Solutions are also available in 100 and 500-milliliter volumes.
Other Information on Sodium Acetate
1. Synthesis of Sodium Acetate
Sodium acetate can be synthesized by several methods:
- Reacting acetic acid with sodium hydroxide: CH3COOH + NaOH → CH3COONa + H2O
- Reacting acetic acid with sodium carbonate: CH3COOH + Na2CO3 → CH3COONa + NaHCO3
- Reacting calcium acetate with sodium sulfate: Ca(CH3COO)2 + Na2SO4 → 2CH3COONa + CaSO4
2. Application to Heat Packs
Sodium acetate trihydrate is utilized in reusable heat packs. Sealed in a plastic bag and melted by heating above its melting point, it remains liquid even when cooled down. Physical stimulation triggers crystallization, releasing heat in the process. This feature makes it a convenient, reusable warming tool.