1. Pure substances and mixtures

2. Pure substances and particles Pure substances consist of only one type of particle These particles may be atoms, molecules or ions (note: ions go in small groups) If a material has more than one type of particle then it must be a mixture.

3. Mixtures Mixtures may be made between any phases of matter. Solids mixed with liquids Liquids mixed with gases Gases mixed with solids Solids mixed with other solids Liquids mixed with other liquids Gases mixed with other gases

4. Everyday mixtures The type of mixture will depend on the relative proportions of each component Think of substances that you come across in everyday life – can you think of examples of mixtures with different states as the components?

5. Examples solid- solid: a metal coin (copper metal mixed with nickel metal) solid - liquid: coffee, paint solid - gas: foam, smoke liquid - liquid: milk, wine liquid - gas: fizzy water, water vapour gas - gas: air

6. Separation of mixtures How can you... separate the mixtures that you thought of in the last section? How can you… separate a solid from a liquid when… 1. they do not form a solution? 2. they do form a solution?

7. Purification of a mixture You are provided with a mixture of soil and water. Plan a method to prepare pure water. You should describe apparatus and method for your experiment. How could you demonstrate that the water that you have prepared is pure? What would also have to be done to make it safe for drinking?

8. Pure water in the world There are many places in the world where water supply is a problem. There may be a lot of water but it is not drinkable for one reason or another. Research the problems and solutions available to the world’s water supply. How is pure safe water made available in such areas? Is this important in all the world?