Separation of salt 1. Put some of the solution from the conical flask into an evaporating dish.
2. Place the evaporating dish on a beaker of water. 3. Heat the beaker to evaporate the water from the evaporating dish.
4. Observe and record your results. SL
Group work Pair up with a student from another group and discuss the following: 1. Were there any steps that you found difficult? 2. What errors might have been made during the experiment?
Salt solution Beaker
Gauze
Clock glass Boiling water Tripod
Bunsen burner
Fig. 12 Separating the salt by evaporation.
p207 fig 9
Extended Investigation Use a titration or other suitable method to test the effectiveness of a range of over-the-counter indigestion remedies.
Nature of Science
To carry out the titration of an acid and a base you had to use practical skills. You also had to think about what you were doing. Whenever scientists carry out investigations they review and reflect on the skills and thinking used. Questions 1. Why do you think it is important to review and reflect on the skills and thinking used in carrying out scientific investigations?
2. What are your reflections on the skills and thinking that you used to investigate acids and bases?
Chapter Summary
1. Acids are substances that turn blue litmus red. 2. Concentrated acids are very corrosive. 3. Bases are substances that turn red litmus blue. 4. Bases have a soapy feel when they react with water. 5. Bases that dissolve in water are called alkalis. 6. Concentrated bases are very corrosive. 7. The pH scale is used to indicate how acidic or basic a substance is.
