Chemistry Chapters

1. Atomic Structure2. Periodic Classification of Elements3. Chemical Bonding4. Oxidation and Reduction5. Acids Bases Salts6. Behaviour of Gases7. Electrolysis8. Carbon and its Compounds9. Fuels10. Metallurgy11. Important Facts About Some Metals12. Non Metals13. Common Facts

Acids, Bases & Salts

“Acids, bases, and salts are fundamental chemical compounds with distinct properties and wide-ranging applications in daily life and industry.”

What are Acids?

Acids are substances that release hydrogen ions (H⁺) in aqueous solutions. They have a sour taste and turn blue litmus red.

  • Examples: Hydrochloric acid (HCl), Sulphuric acid (H₂SO₄), Citric acid
  • Uses: Cleaning, digestion, manufacturing fertilizers

What are Bases?

Bases are substances that release hydroxide ions (OH⁻) in aqueous solutions. They have a bitter taste, slippery feel, and turn red litmus blue.

  • Examples: Sodium hydroxide (NaOH), Calcium hydroxide (Ca(OH)₂), Ammonia (NH₃)
  • Uses: Soap making, neutralizing acids, industrial cleaning

What are Salts?

Salts are formed when an acid reacts with a base in a neutralization reaction. They consist of positive ions from the base and negative ions from the acid.

Example: HCl + NaOH → NaCl + H₂O

  • Common salt (NaCl): Used in food
  • Baking soda (NaHCO₃): Used in baking
  • Washing soda (Na₂CO₃): Used in cleaning

Indicators

Indicators are substances that change color in acidic or basic solutions and are used to detect their presence.

  • Litmus: Red in acid, blue in base
  • Phenolphthalein: Colorless in acid, pink in base
  • Methyl orange: Red in acid, yellow in base

pH Scale

The pH scale measures the concentration of hydrogen ions in a solution. It ranges from 0 to 14.

  • pH < 7: Acidic
  • pH = 7: Neutral
  • pH > 7: Basic

Examples:

  • Gastric juice: pH ~1.2
  • Pure water: pH 7
  • Soap solution: pH ~9-10

Important Salts and Their Uses

  • Sodium chloride (NaCl): Table salt
  • Baking soda (NaHCO₃): Antacid and baking ingredient
  • Washing soda (Na₂CO₃·10H₂O): Softens water
  • Plaster of Paris (CaSO₄·½H₂O): Used in casting and sculptures

Previous Year Questions

  • SSC JE 2017: Which acid is present in the stomach?
  • Hydrochloric acid (HCl)
  • RRB ALP 2018: Which indicator turns pink in base?
  • Phenolphthalein
  • HSSC 2019: What is the pH value of neutral solution?
  • 7
Did You Know? Bee stings are acidic in nature and can be neutralized using baking soda (a base).

Conclusion

Acids, bases, and salts are crucial substances with distinct chemical properties and practical uses. From digestion in the human body to soap making and industrial cleaning, understanding their behavior helps in various fields of science and industry.

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