1. What is a mixture Aims: –To be able to draw particle pictures to represent elements, compounds and mixtures –To be able to identify suitable methods for the separation of mixtures

2. Mixture Drinking water is clean but not pure –Contains other chemicals apart from water –Flows over rocks Water is a compound and other chemicals dissolved in it are also compounds Mineral water is a mixture of compounds

3. A mixture is not the same as a compound: 1. The proportions of the substances in a mixture are not fixed. 2. The properties of a mixture are often an “average” of the properties of its ingredients (e.g. a mixture of a black and white powder is grey). 3. The substances in a mixture are just mixed, not chemically joined, and so it is usually quite easy to separate the ingredients (e.g. it is easy to get salt from sea water). mixed A mixture contains two or more substances that are mixed together but have not reacted with each other. Sea water is a mixture of salts, water and other substances. What is a mixture?

4. Mixtures 100 g 105 g Before After

5. Element, mixture or compound? Salty waterHydrogen Hydrochloric acid Sodium chloride (salt) Diamond Air

6. Filtering (filtration) This is good for separating an insoluble solid from a liquid; –an insoluble substance does not dissolve in water. –For example, separating sand from a mixture of sand and water.

7. Filtration 3) 1)2)

8. Evaporation This is good for separating a soluble solid from a liquid; –a soluble substance dissolves in water to form a solution. –For example, copper sulfate crystals can be separated from copper sulfate solution using evaporation.

9. Evaporation 3) 1)2)

10. Chromatography This is good for separating dissolved substances that have different colours –Inks and plant dyes. It works because some of the coloured substances dissolve in the liquid better than others, so they travel further up the paper

11. Chromatography 3) 1) 2)

12. Simple distillation This is good for separating a liquid from a solution. –For example, water can be separated from salty water by simple distillation. This method works because the liquid evaporates from the solution, but is then cooled and condensed into a separate container. The salt does not evaporate and so it stays behind.

13. Simple distillation 1) 2)

14. How can each mixture be separated? alcoholalcohol and water cooking oilcooking oil and water watersea water saltsea water glassglass and water MethodWantedMixture filter evaporate distil pipette distil Separating mixtures

15. True or false?