2. Starter – What do these hazard symbols mean?

3. You need to know what all these symbols mean to keep you safe in science.

4. Harmful These chemicals are similar to toxic chemicals but are less dangerous.

5. Irritant These chemicals cause redness or blistering of the skin.

6. Oxidising agent These chemicals help other chemicals to burn more fiercely.

7. Corrosive These chemicals attack and destroy living tissue including the eyes and skin.

8. Toxic These chemicals can cause death. They may have their effects when swallowed, absorbed through the skin or breathed in.

9. Flammable These chemicals catch fire easily.

10. Radioactive These substances can cause burns and cancer.

11. Harmful to the environment These chemicals will damage plant or animal life.

12. Signs used in the Lab How many can you recognise?

27. Lesson Objectives Recall what different hazard warning symbols mean. (Level 3) Name some common acids and alkalis. (Level 4) Evaluate different uses for acids and alkalis (Level 5)

28. Copy these headings and write AS MUCH AS YOU CAN about what you already know. AcidAlkali

29. They are chemicals They react with each other They can be concentrated or dilute Concentrated acids can be corrosive Concentrated alkalis can be caustic They are measured using the pH system

30. Foods - Berries and citrus fruits are acidic. They contain Citric acid. Bicarbonate of soda and chocolate are alkaline. In the body- Stomach juices are acidic. They contain Hydrochloric acid. Pancreatic juices are alkaline. Cleaning products- Products containing ammonia are alkaline Products containing vinegar are acidic. They contain Ethanoic acid.

31. A bee sting is acidic, a wasp sting is alkaline

32. Write an account of what life would be like without acids or alkalis.