Summary
NCERT Class 10 Science Chapter 2 covers Acids, Bases and Salts — explaining their chemical properties, the pH scale (0–14), neutralisation reactions, and important salts like baking soda, washing soda, bleaching powder, and Plaster of Paris derived from common salt.
Chapter 2 of NCERT Class 10 Science explores the chemical properties of acids and bases, showing how acids produce H⁺(aq) ions in water while bases produce OH⁻(aq) ions. It explains neutralisation (Acid + Base → Salt + Water), the pH scale from 0 to 14, and the everyday importance of pH in digestion, tooth decay, and acid rain. The chapter also covers industrially important salts — sodium hydroxide (chlor-alkali process), bleaching powder, baking soda (NaHCO₃), washing soda (Na₂CO₃·10H₂O), and Plaster of Paris — all derived from common salt.
Key points & formulas
- 01Acids turn blue litmus red and produce H⁺(aq) ions in water; bases turn red litmus blue and produce OH⁻(aq) ions in water.
- 02Acid + Metal → Salt + Hydrogen gas; Metal carbonate + Acid → Salt + Carbon dioxide + Water.
- 03Neutralisation reaction: Acid + Base → Salt + Water; e.g., NaOH(aq) + HCl(aq) → NaCl(aq) + H₂O(l).
- 04The pH scale (0–14) measures hydrogen ion concentration: pH 7 is neutral, below 7 is acidic, above 7 is basic. Human body functions within pH 7.0–7.8.
- 05Tooth decay begins when mouth pH drops below 5.5; toothpastes are basic to neutralise excess acid. Acid rain has pH less than 5.6.
- 06Common salt (NaCl) is the raw material for NaOH (chlor-alkali process), bleaching powder Ca(ClO)₂, baking soda NaHCO₃, and washing soda Na₂CO₃·10H₂O.
Frequently asked questions
01What is the difference between a strong acid and a weak acid according to NCERT Class 10 Chapter 2?
Acids that produce more H⁺ ions in solution are called strong acids, while acids that produce fewer H⁺ ions are called weak acids. For example, hydrochloric acid (HCl) is a strong acid and acetic acid (CH₃COOH) is a weak acid; at the same concentration, HCl produces more hydrogen ions than acetic acid.
02How is bleaching powder manufactured and what are its uses?
Bleaching powder is produced by the action of chlorine gas on dry slaked lime: 2Ca(OH)₂ + 2Cl₂ → Ca(ClO)₂ + CaCl₂ + 2H₂O. It is used for bleaching cotton and linen in textile industries, bleaching wood pulp in paper factories, and for disinfecting drinking water.
03What is the chlor-alkali process and what products does it yield?
When electricity is passed through an aqueous solution of sodium chloride (brine), it decomposes as: 2NaCl(aq) + 2H₂O(l) → 2NaOH(aq) + Cl₂(g) + H₂(g). The three useful products are sodium hydroxide (formed near the cathode), chlorine gas (at the anode), and hydrogen gas (at the cathode).
04Is the NCERT Class 10 Science Chapter 2 PDF free to download?
Yes, the NCERT Class 10 Science Chapter 2 PDF is completely free to download on cbseprepmaster.com.
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This is the complete Science Chapter 2 as published by NCERT — every diagram, solved example, and exercise included, free. Browse all CBSE Class 10 textbooks.
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