Class 10 Science Acids Bases and Salts Notes

Introduction

• Acids: Substances that release H⁺ ions in water.
  • Examples: HCl, H₂SO₄
• Bases: Substances that release OH⁻ ions in water.
  • Examples: NaOH, Ca(OH)₂
• Salts: Compounds formed when an acid reacts with a base.
  • Example: HCl + NaOH → NaCl + H₂O

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Properties of Acids and Bases

Property	Acid	Base
Taste	Sour	Bitter
Touch	Corrosive	Slippery
Litmus Test	Turns blue → red	Turns red → blue
Conductivity	Conduct electricity	Conduct electricity

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pH Scale

• Measures acidic or basic nature of a solution
• Scale ranges from 0 to 14:
  • pH < 7 → Acidic
  • pH = 7 → Neutral
  • pH > 7 → Basic
• Examples:
  • Lemon juice pH ≈ 2
  • Soap solution pH ≈ 12

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Neutralization Reaction

• Reaction between an acid and a base producing salt and water
• Example: HCl + NaOH → NaCl + H₂O
• Applications:
  • Treating acidity with antacids
  • Making fertilizers

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Types of Salts

1. Normal salts: Formed when all H⁺ of an acid is replaced by metal ions
   • Example: NaCl
2. Acidic salts: Some H⁺ remains unreacted
   • Example: NaHSO₄
3. Basic salts: Some OH⁻ remains unreacted
   • Example: Cu₂(OH)Cl

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Preparation of Salts

1. Reaction of acids with metals:
   • Zn + H₂SO₄ → ZnSO₄ + H₂
2. Reaction of acids with bases:
   • HCl + NaOH → NaCl + H₂O
3. Reaction of acids with metal carbonates:
   • CaCO₃ + 2HCl → CaCl₂ + CO₂ + H₂O

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Importance and Uses

• Salts: Table salt (NaCl), Baking soda (NaHCO₃)
• Acids: HCl in digestion, H₂SO₄ in industry
• Bases: Ca(OH)₂ in construction, NaOH in soap making