Class 10 Science Chapter 2, Acids, Bases and Salts, examines the chemical behaviour of acids and bases with metals, metal carbonates, metal oxides and each other, introduces the $\text{pH}$ scale ($0$ to $14$), and details the preparation and uses of five industrially important sodium and calcium salts.
What Class 10 Science Chapter 2 Covers
2.1 Understanding the Chemical Properties of Acids and Bases uses natural (litmus, turmeric), synthetic (methyl orange, phenolphthalein) and olfactory indicators (onion, vanilla, clove oil), then tests reactions of acids and bases with metals (evolving $\text{H}_2$ gas that burns with a pop sound), metal carbonates/hydrogencarbonates (evolving $\text{CO}_2$ that turns lime water milky, $\text{Ca(OH)}_2 + \text{CO}_2 \rightarrow \text{CaCO}_3\downarrow + \text{H}_2\text{O}$), and neutralisation.
2.2 & 2.3 What Do All Acids and Bases Have in Common & Strength of Solutions shows that acids conduct electricity in aqueous solution by producing hydronium ions ($\text{H}_3\text{O}^+$) while bases produce $\text{OH}^-$ ions, explains why acid must be added slowly to water (never water to concentrated acid), and applies universal indicator and $\text{pH}$ to soil, digestion, tooth decay below $\text{pH } 5.5$, and bee/nettle stings (methanoic acid).
2.4 More About Salts covers the chlor-alkali process ($2\text{NaCl(aq)} + 2\text{H}_2\text{O(l)} \rightarrow 2\text{NaOH} + \text{Cl}_2 + \text{H}_2$), bleaching powder ($\text{CaOCl}_2$), baking soda ($\text{NaHCO}_3$), washing soda ($\text{Na}_2\text{CO}_3\cdot 10\text{H}_2\text{O}$), water of crystallisation in hydrated copper sulphate ($\text{CuSO}_4\cdot 5\text{H}_2\text{O}$), and Plaster of Paris ($\text{CaSO}_4\cdot\frac{1}{2}\text{H}_2\text{O}$ from gypsum at $373\text{ K}$).
Exercises in Chapter 2
- In-text Questions ask why curd and sour substances should not be kept in brass or copper vessels, why dry HCl gas does not change the colour of dry litmus paper, and why Plaster of Paris should be stored in a moisture-proof container.
- Chapter Exercises (15 Questions) cover pH rankings, neutralisation reactions, why distilled water does not conduct electricity whereas rainwater does, and uses of baking soda and washing soda.
Read Class 10 Science Chapter 2 Online
More Chapters
- Previous: Chapter 1: Chemical Reactions and Equations
- Next: Chapter 3: Metals and Non-metals
- Hindi medium: Class 10 Science Chapter 2 PDF in Hindi (Vigyan)
- All Science chapters and the other Class 10 books: Class 10 NCERT books 2026-27
- All Class 1 to 12 NCERT Textbooks: NCERT Books PDF (Class 1–12)
FAQ
Why should Plaster of Paris be stored in a moisture-proof container?
Plaster of Paris ($\text{CaSO}_4\cdot\frac{1}{2}\text{H}_2\text{O}$) absorbs moisture and reacts with water to form hard solid gypsum ($\text{CaSO}_4\cdot 2\text{H}_2\text{O}$), making it unusable for setting.
Why does dry HCl gas not change the colour of dry litmus paper?
Acids release hydrogen ions ($\text{H}^+$ or $\text{H}_3\text{O}^+$) only in the presence of water. Without water, dry HCl gas does not ionise and therefore shows no acidic behaviour.