Acids, Bases & Salts

What this lesson covers

Acids, Bases & Salts is a 10-part Class 7 Science lesson. Each part makes one point and then hands over to the next, so it can be read in a sitting or picked up again at the part you stopped on. It defines the idea in plain words before using it, works through an example step by step, breaks the topic into its parts and compares them, shows where it is used outside the textbook, names the mistakes that cost marks in an exam, ends with a recap of what to remember.

How it begins

Acids: sour taste, pH below 7, turn blue litmus red. Lemon juice, vinegar, stomach acid. Bases: bitter, slippery, pH above 7, turn red litmus blue. A base that dissolves in water is called an alkali. Neutral: pH exactly 7. Pure water. Never taste or touch a laboratory chemical to identify it. Strong acids and strong alkalis both cause serious burns, and alkalis are often the more damaging to skin and eyes.

The 10 parts

1. Three families of substance
2. Indicators
3. The pH scale is not linear
4. Neutralisation
5. Neutralisation you have used
6. Strong and concentrated are different
7. Acids and bases around you
8. Where it usually goes wrong
9. What to remember
10. Watch one worked through