TEACHGYAN · CLASS 10 · SCIENCE · CHAPTER 2
Acids, Bases and Salts
Premium chapter notes · NCERT-aligned · CBSE 2026–27
1. Acids and bases in everyday life
Many familiar substances show acidic or basic properties. Lemon juice and vinegar are acidic, while soap solution and lime water are basic. These properties can be identified using indicators and by observing characteristic chemical reactions.
Base: In aqueous solution, a base furnishes hydroxide ions (OH⁻).
Examples: Hydrochloric acid (HCl), sulphuric acid (H₂SO₄) and ethanoic acid (CH₃COOH) are acids. Sodium hydroxide (NaOH), potassium hydroxide (KOH) and calcium hydroxide [Ca(OH)₂] are bases.
2. Indicators: identifying acids and bases
Indicators are substances that show a visible change, such as a colour change or smell change, in acidic and basic solutions.
| Indicator | In an acidic solution | In a basic solution |
|---|---|---|
| Blue litmus | Turns red | Remains blue |
| Red litmus | Remains red | Turns blue |
| Phenolphthalein | Colourless | Pink |
| Methyl orange | Red | Yellow |
| Turmeric | Remains yellow | Turns reddish-brown |
Blue litmus → Red
Methyl orange → Red
Red litmus → Blue
Phenolphthalein → Pink
3. Chemical properties of acids and bases
Acids react with certain metals to release hydrogen gas, with metal carbonates and hydrogencarbonates to release carbon dioxide, and with bases in neutralisation reactions. Bases also react with some metals, such as zinc and aluminium, under suitable conditions.
Unlock the complete resource
Get the complete paper or study resource, including all locked sections and the teacher’s marking scheme where provided.
₹29.00
Unlock Full ResourceAlready purchased? Log in to access your notes.