2. Separating Mixtures Chapter 25

3. Decanting Decanting means to pour off. Decanting is used in panning gold and in pouring water off vegetables.

4. Separating Solids from Liquids Filtration is the separation of small insoluble solids from a liquid. e.g. sand from water,Chalk from water

5. Evaporation

6. To purify Rock Salt(sand and salt) using filtration and evaporation. Step (a) Crush rock salt with pestle and mortar. Step (b) Add crushed rock to warm water. Step (c) Heat water and stir thoroughly.

7. Step (d) Allow beaker to cool and filter the mixture. Step (e) Heat the salt solution until it starts to “spit”. Step (f) Continue heating the solution over a beaker of boiling water until dry salt remains in the dish.

8. Distillation Distillation is the process involving the vaporisation of a liquid by boiling it and then condensing the liquid by cooling it. It can be used to separate a soluble solid (e.g. Salt) from a liquid (e.g.seawater) to give a pure sample of each.

9. Apparatus used to obtain a sample of pure water from seawater(distillation)

10. Distillation can also be used to separate two miscible liquids such as alcohol and water. It works on the basis that alcohol boils at 78 o C and water boils at 100 o C. The fractionating column helps to give better separation of the Alcohol and the Water

11. Chromotography Chromatography is a method used to separate a mixture of dissolved substances in a solution.

12. As the solvent rises up the paper it carries some dyes further up than others. This separates the various dyes from the original sample. Before After

13. TextbookChapter24-Separating Mixtures A1.Physical. A2. Insoluble. A3. Soluble, solution. A4. Filtration, filter paper. A5. Salt, sugar, evaporation, crystals, clock glass. A6. 78, 100, distillation, Liebig condenser. A7. Distillate. A8. Soluble, solution. A9. Distillation. A10. Chromatography, chromatography paper. A11. Soluble. B1. See Experiment 25.1, p.148. B2. See Experiment 25.3, p.148.

14. DiscoveringScience-TextbookSolutions28 B3. (a) Distillation. (b) Alcohol has a lower boiling point and there fore evaporates quicker than water does. The alcohol vapour enters the inner tube of the Liebig condenser, the walls of which are kept cold by the water flowing in the outer sleeve of the condenser. This condenses the alcohol vapour into alcohol liquid. (c) So that the outer tube will fill completely with cold tap water. B4. SeeExperiment24.3,p.146. B5. (a) A magnet. (b) Saw dust would float and could be scooped off. (c) Filtration followed by evaporation. (d) Filtration. (e) Evaporation, or distillation to save a sample of water. (f) A magnet.

15. B6. (a)Sand (b)Ink. (c)Alcohol. (d)Copper sulfate.(e)Salt and water. (f)Sand and water. (g)Alcohol and water. B7. See Experiment 24.1, p.145. B8. (a)Distillation. (b)Alcohol and water. (c)Liebig condenser. (d)Filtration. B9.(a)See Experiment 24.4,p.147. (b)The mixture of coloured inks would separate out and end up at different levels on the chromatography paper. A single coloured ink would only leave one mark on the chromatography paper. B10. (a)(a) Liebig condenser. (b)Y. (c)Pure water, salt. B11.(a)The ink spot moves upwards and the different colours in the ink get separated out at different levels on the chromatography paper. (b)The ink spot would move upwards and only one mark would be left higher up on the chromatography paper.