Revision Notes: Class 10 Science Chapter 2 Acids, Bases and Salts

A fast, one-glance recap of Class 10 Science Chapter 2 (Acids, Bases and Salts) — for the full worked explanations, see the Solutions. These Class 10 Science Chapter 2 notes are ideal for quick revision just before exams.

Last Updated: July 21, 2026

Why This Chapter Matters

Acids, Bases and Salts is one of the standard chapters in the CBSE/NCERT Class 10 Science syllabus and questions from it appear regularly in board exams, in formats ranging from 1-mark objective questions to longer 3-5 mark descriptive or numerical questions. Because the concepts here often build on earlier chapters (and feed into later ones), a solid grip on this chapter also makes the rest of the Science syllabus easier to follow.

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

How to Use These Notes

These revision notes are meant for quick recall in the last few days before an exam or unit test — they are not a substitute for first reading the full chapter and working through examples in the NCERT textbook. A good routine is: read the chapter once, solve the in-text and end-of-chapter questions using the linked Solutions, then come back to this page a day or two before the exam to refresh the key definitions and formulas without re-reading the whole chapter.

Written by Satish

NCERTBooks.org is an independent educational resource run by a small team focused on making official NCERT textbooks easy to find, read, and download for students, parents, and teachers across India. We are not affiliated with NCERT or the Ministry of Education -- we organise publicly available NCERT content by class and subject, verify links against official sources, and build tools (like our in-browser reader) that make studying more convenient. Every guide we publish is written and reviewed by our team based on the actual NCERT curriculum and syllabus.