Acids and Bases

Key Notes :

Understanding Acids and Bases:

  • Acids: Substances that release hydrogen ions (H⁺) when dissolved in water. They taste sour and can turn blue litmus paper red. Examples include lemon juice and vinegar.
  • Bases: Substances that release hydroxide ions (OH⁻) when dissolved in water. They taste bitter and can turn red litmus paper blue. Examples include baking soda and soap.

Properties of Acids:

  • Sour taste.
  • Can conduct electricity in solution.
  • React with metals to produce hydrogen gas.
  • Examples: Citric acid in citrus fruits, acetic acid in vinegar.

Properties of Bases:

  • Bitter taste.
  • Slippery or soapy feel.
  • Can conduct electricity in solution.
  • Examples: Sodium hydroxide in drain cleaners, magnesium hydroxide in antacids.

pH Scale:

pH Scale: Measures how acidic or basic a substance is, ranging from 0 to 14.

  • pH < 7: Acidic.
  • pH = 7: Neutral (e.g., water).
  • pH > 7: Basic (alkaline).

Indicators:

Litmus Paper: Changes color to indicate acidity or basicity.

  • Red Litmus Paper: Turns blue in a base, stays red in an acid.
  • Blue Litmus Paper: Turns red in an acid, stays blue in a base.

Universal Indicator: Changes color to show the pH level of a solution.

Neutralization Reaction:

Neutralization: A chemical reaction between an acid and a base that produces salt and water.

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

Safety:

  • Always handle acids and bases with care.
  • Wear safety goggles and gloves.
  • Follow proper procedures for dilution and disposal.

Everyday Examples:

  • Acids: Citrus fruits, soda, and yogurt.
  • Bases: Toothpaste, baking soda, and ammonia.

Let’s practice!