Lesson 12 of 14
The big picture
Show on a big screenEvery substance is acidic, basic or neutral. An indicator shows which.
| Idea | Remember | Example |
|---|---|---|
| Three groups | Never taste an unknown substance. Test it with litmus paper. | acidic, basic or neutral |
| Acids | Foods that taste sour tend to contain an acid. Acids turn blue litmus red. | curd: lactic acid |
| Bases | A base turns red litmus blue. A bitter taste alone does not make a base. | soap, baking soda |
| Indicators | Turmeric turns red in a base only. Red rose is red in an acid and green in a base. | turmeric paper |
| Neutral | Blue and red litmus both unchanged means neutral. Turmeric cannot tell acidic from neutral. | salt solution |
| Neutralisation | An acid and a base cancel each other. They make salt and water, and give out heat. | baking soda on an ant bite |
| Plant indicators | Every indicator has its own colours. Red shows an acid with rose extract but a base with turmeric. | turmeric paper: red in a base |
| Smell indicators | An olfactory indicator changes its smell. Onion smell stays in an acid and fades in a base. | onion strip |
| Soil and waste | Lime treats acidic soil. Acidic waste is neutralised before release. | lime on acidic soil |
Now open Chapter 2 in your NCERT book. Read it again, now with these ideas.