Acids, Bases and Salts

1. Properties of Acids and Bases

Acids are substances that taste sour and turn blue litmus red.

• They release H⁺ ions in water.
• Examples: Lemon juice, vinegar, hydrochloric acid (HCl).

Bases are substances that taste bitter and turn red litmus blue.

• They release OH⁻ ions in water.
• Examples: Soap solution, baking soda, sodium hydroxide (NaOH).

Example: Lemon contains citric acid which gives it a sour taste. Soap contains a base that feels slippery.

2. Natural Indicators Around Us

Certain natural substances help us identify acids and bases by changing color. These are called indicators.

• Litmus: Extracted from lichens. Turns red in acid and blue in base.
• Turmeric: Turns red in base, no change in acid.
• China Rose (Hibiscus): Turns dark pink in acid and green in base.

Example: If you put soap water (a base) on turmeric paper, it turns red.

3. Neutralization Reaction

A neutralization reaction occurs when an acid and a base react to form salt and water. It is usually accompanied by heat.

Equation:
Acid + Base → Salt + Water

Example:
Hydrochloric acid (HCl) + Sodium hydroxide (NaOH) → Sodium chloride (NaCl) + Water (H₂O)

Note: Neutralization helps in reducing the harmful effects of acids or bases.

4. Uses of Neutralization in Daily Life

• Indigestion: Too much acid in the stomach causes discomfort. Antacids like milk of magnesia neutralize the acid.
• Soil Treatment: If soil is too acidic, farmers add quick lime (a base) to neutralize it.
• Wasp/Bee Stings: Wasp sting is alkaline and is treated with a weak acid like vinegar. Bee sting is acidic and can be treated with baking soda (a base).
• Factory Waste: Acidic waste from factories is treated with basic substances before being released into rivers.

Example: A person with acidity takes an antacid tablet to get relief — this is neutralization at work!

Summary

• Acids taste sour; bases taste bitter and feel slippery.
• Indicators help identify acidic or basic nature.
• Neutralization forms salt and water and is used in many real-life applications.