1. Chapter 19 Separating Mixtures A mixture consists of two or more substances mingled together but not chemically combined. Examples of mixtures: Sea water = water + other substances dissolved in it (e.g. salt) Crude oil = petrol, diesel, tar and lots of other substances Air = oxygen, nitrogen, carbon dioxide and other gases We can separate mixtures using a variety of techniques: Example:

2. 1.Filtration Filtration is used to separate an insoluble solid e.g. sand or soil and a liquid e.g. water. It involves using a sieve or filter paper. Filter paper has tiny pores (holes) which allow tiny particles through but block larger particles..

3. 2. Evaporation Evaporation is used to separate a soluble solid e.g. salt from a Liquid e.g. water. It involves heating the solution until the solvent e.g. water evaporates leaving behind the solute e.g. the salt Salt – which is mined from the ground is called rock salt. It is a mixture of salt, sand and gravel. It is spread on roads in winter to prevent them becoming icy. 3. Distillation – method of separation which can separate a soluble solvent e.g. salt from a solvent e.g. water or two miscible liquids (two liquids that mix) e.g. alcohol and water.

4. 4. Chromatography Paper chromatography can be used to separate mixtures of substances which are in a solution. The different substances travel up the paper at different speeds.