Acids, Bases & Salts

What this lesson covers

Acids, Bases & Salts is a 7-part O Level Chemistry 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

An acid produces H⁺ ions in water. An alkali produces OH⁻ ions. A base is anything that neutralises an acid (metal oxides and hydroxides, ammonia) and an alkali is a base that dissolves. Neutralisation is one ionic equation: H⁺ + OH⁻ → H₂O. The pH scale runs 0 to 14. Below 7 acidic, 7 neutral, above 7 alkaline. Universal indicator: red in strong acid, orange-yellow in weak, green neutral, blue-purple alkaline.

The 7 parts

1. Acids and bases in terms of ions
2. The three reactions of an acid
3. Making salts: the three methods and when each applies
4. Identifying ions: the tests as the paper wants them
5. Where marks go
6. What to remember
7. Watch one worked through