1. What Is Acetic Acid?

Acetic acid (CH₃COOH) is a simple carboxylic acid and the main component of vinegar. It is a colorless liquid with a pungent odor and sour taste, widely used in both industrial and household applications.

2. Chemical Structure and Properties

The chemical formula CH₃COOH represents:

Molecular Structure:

• Molecular Formula: C₂H₄O₂
• Structural Formula: CH₃-COOH
• Molar Mass: 60.05 g/mol
• Boiling Point: 118°C
• Melting Point: 16.6°C
• Density: 1.05 g/cm³

Chemical Properties: Weak acid (pKa = 4.76), miscible with water, ethanol, and ether. Forms acetate salts with bases.

3. Vinegar Composition

Vinegar typically contains:

• Acetic acid: 5-20% by volume
• Water: 80-95%
• Trace compounds: Flavors, colors, minerals
• pH range: 2.4-3.4 depending on concentration

Different types of vinegar have varying acetic acid concentrations:

• Table vinegar: 5-8% acetic acid
• Pickling vinegar: 7-10% acetic acid
• Cleaning vinegar: 10-20% acetic acid
• Glacial acetic acid: 99-100% pure

4. Industrial and Household Uses

Industrial Applications:

• Production of vinyl acetate monomer (plastics)
• Manufacture of acetic anhydride
• Solvent for recrystallization
• Chemical reagent in laboratories

Household Uses:

• Culinary: Food preservative, flavoring agent
• Cleaning: Natural disinfectant, descaler
• Gardening: Weed killer, pH adjuster
• Health: Traditional remedies

5. Frequently Asked Questions (FAQ)

Q1: What does "aq" mean in chemical formulas?
A: "aq" stands for aqueous, meaning dissolved in water. CH₃COOH (aq) indicates acetic acid dissolved in water.

Q2: Why is acetic acid concentration in vinegar limited to 5-20%?
A: Higher concentrations become corrosive and hazardous for household use. Food-grade vinegar is typically 5-8% for safety.

Q3: What is glacial acetic acid?
A: Glacial acetic acid is the pure, concentrated form (99-100%) that solidifies just below room temperature, hence "glacial."

Q4: How is acetic acid produced industrially?
A: Mainly through methanol carbonylation or by bacterial fermentation of ethanol for food-grade acetic acid.

Q5: Is vinegar the same as acetic acid?
A: No, vinegar is a dilute solution of acetic acid (5-20%) in water, while acetic acid refers to the pure chemical compound.