Sodium Acetate (CH₃COONa) is the sodium salt of acetic acid. It appears as a white crystalline powder, either odorless or with a faint vinegar-like smell (especially when heated). Sodium acetate is slightly hygroscopic, particularly in its anhydrous form, and exists in two common forms:

Anhydrous (dry) sodium acetate, and
Hydrated sodium acetate, typically the trihydrate form (CH₃COONa·3H₂O).

Chemical Structure of Sodium Acetate

Sodium acetate is an ionic compound composed of a sodium cation (Na⁺) and an acetate anion (CH₃COO⁻).
The acetate ion contains a methyl group (CH₃) bonded to a carboxylate group (COO⁻). Within the carboxylate group, the double bond between carbon and oxygen exhibits resonance, meaning the negative charge is delocalized over both oxygen atoms.

Chemical formula: CH₃COONa
Resonance structure: O=C–O⁻ ↔ ⁻O–C=O

Properties of Sodium Acetate

Property	Description
Appearance	White crystalline powder
Odor	Odorless; may emit a vinegar-like smell when heated
Solubility	Highly soluble in water; slightly soluble in ethanol (~1.4 g/100 mL)
Hygroscopicity	The anhydrous form absorbs moisture from air
pH Nature	A salt of a weak acid (acetic acid) and a strong base (NaOH); aqueous solutions are slightly basic (pH 8–9 for 0.1 M solution)
Melting Point	Anhydrous: decomposes around 324°C; Trihydrate: melts at ~58°C, releasing its water of crystallization
Buffer Capacity	Forms a buffer with acetic acid, effective in pH range 4.0–6.5
Chemical Behavior	Can release acetic acid or CO₂ upon contact with strong acids or oxidizing agents

Applications of Sodium Acetate

1. Food Industry

Used as a food additive (E262) for pH control, flavoring (salty/sour), and preservation.
Exhibits antibacterial and antifungal properties in certain food formulations.

2. Pharmaceutical and Medical Applications

Used as a source of sodium in IV infusions and dialysis solutions.
Functions as a buffering agent in pharmaceutical formulations and biological reactions.

3. Textile Industry

Serves as a dyeing assistant and pH regulator in dye baths.
Neutralizes residual acids such as sulfuric acid (H₂SO₄).
Helps prevent static electricity on fabrics.

4. Construction Industry

Used as an additive in concrete to control pH and improve frost resistance (acts as a sealing agent).

5. Laboratory Applications

Widely used in buffer preparation (especially in biochemistry and DNA extraction).
Acts as a carbon source for bacterial cultures.
Included in extraction and purification solutions in molecular biology.

6. Hand Warmers and Heat Packs

In supersaturated sodium acetate trihydrate solutions, rapid crystallization releases latent heat (approximately 264–289 kJ/kg)—used in reusable heating pads.

7. Other Industrial Uses

Rubber industry: delays vulcanization of chloroprene.
Leather tanning and dye production: acts as a process regulator.

Advantages of Sodium Acetate

✅ FDA-approved as safe for food use (within regulated limits)
✅ Effective buffering properties
✅ High compatibility with industrial processes
✅ Low cost and readily available
✅ Exhibits antimicrobial and preservative effects
✅ Useful in phase-change thermal systems

Disadvantages of Sodium Acetate

⚠️ Hygroscopic (especially the anhydrous form) — requires sealed storage
⚠️ Irritating to eyes and skin upon contact
⚠️ Inhalation of dust may cause respiratory irritation
⚠️ Ingestion in excess may lead to gastrointestinal discomfort or hypernatremia
⚠️ Decomposes at high temperatures, releasing irritating vapors
⚠️ Should be used with caution in renal or cardiac patients due to electrolyte effects
⚠️ Some pharmaceutical forms may contain aluminum or other excipients, requiring special care in premature infants or renal patients