A fast, one-glance recap of Class 10 Science Chapter 2 (Acids, Bases and Salts) — for the full worked explanations, see the Solutions.
Revision Notes: Acids, Bases and Salts
- Acid: releases H⁺ (as H₃O⁺) ions in water — e.g. HCl, H₂SO₄, CH₃COOH
- Base: releases OH⁻ ions in water — e.g. NaOH, KOH, Ca(OH)₂
- Indicators: litmus (red↔blue), phenolphthalein (colourless in acid, pink in base), methyl orange; olfactory indicators like onion/vanilla/clove oil lose their smell in base
- Acid + Metal → Salt + H₂↑ (test: burning splinter gives a pop sound)
- Metal carbonate/bicarbonate + Acid → Salt + CO₂↑ + H₂O (test: CO₂ turns lime water milky)
- Acid + Base → Salt + Water (neutralisation); ionically just H⁺ + OH⁻ → H₂O
- Metallic oxide + Acid → Salt + Water (metallic oxides are basic in nature)
- Non-metallic oxide + Base → Salt + Water (non-metallic oxides are acidic in nature)
- Strong vs weak: strong acids/bases ionise almost completely (HCl, NaOH); weak ones ionise only partially (CH₃COOH, NH₄OH)
- pH scale: 0–14; <7 acidic, =7 neutral, >7 basic; lower pH = higher H⁺ concentration
- pH matters for: soil health, digestion (stomach HCl), tooth decay (enamel erodes below pH 5.5), and plant/animal survival (narrow pH range)
- Water of crystallisation: fixed water molecules per formula unit, e.g. CuSO₄·5H₂O, Na₂CO₃·10H₂O
- Common salts: NaCl (table salt), NaOH (chlor-alkali process), Na₂CO₃·10H₂O (washing soda), NaHCO₃ (baking soda), CaOCl₂ (bleaching powder), CaSO₄·½H₂O (Plaster of Paris)
- Bleaching powder: Ca(OH)₂ + Cl₂ → CaOCl₂ + H₂O
- Plaster of Paris: gypsum (CaSO₄·2H₂O) heated at ~373 K → CaSO₄·½H₂O + 1½H₂O
See also: Extra Questions (HOTS) | Class 10 Science Key Reactions Handbook
