What will we learn in this section ● What pure substance is. ● Separating techniques including, (1) Filtration (2) Evaporation (3) Distillation (4) Chromatograpy Separation Techniques

Many of the substances we see everyday are in fact mixtures. In fact pure substances are rare. Often chemists want obtain a pure substance What is pure substance? A pure substance is one that contains one substance only and nothing else. A pure substance can be an element or compound. This section is about how we can get pure substance(s) from mixtures. The separation method used depends on the type of mixture. Don't forget the animations is stuff and substances showing each technique.

● Filtration – a method of separating an insoluble solid from a liquid e.g soil and water ● What is an insoluble solid? ● How does the filter paper work? ● You must know the names of the pieces of apparatus and the terms filtrate and residue. Separation Techniques

● evaporation – a method of separating a soluble solid from a liquid e.g salt (NaCl) and water ● What is a soluble solid? ● Name the laboratory apparatus used? ● What would you do if the liquid is wanted as well as the solid? ● How might you separate salt from rock salt? ● Rock salt is mixture of NaCl mixed with sand and earth. Separation Techniques

Evaporating basin Salt water mixture Wire guaze Tripod stand Bunsen burner

● DIstillation – a method of separating by evaporating condensing the vapour. e.g seawater Separation Techniques

● DIstillation – a method of separating by evaporating condensing the vapour. e.g seawater. ● What is condensation? ● How does the condenser work? ● Could you separate two liquids like alcohol and water by distillation? ● It you could why would it be possible? Separation Techniques

● Chromatography – a method of separating a mixture of substances in a solution. ● Originally used to coloured materials in plants. ● How it works ● The solvent carries dyes up the paper. ● Some dyes are more soluble in the solvent than others. ● Dyes not very soluble appear near the bottom of the paper ● The more soluble the further up the paper the dye is carried. Separation Techniques

Uses of Chromatography ● In art restoration, used to find out what was in the original paint mixture of the artist. ● Forensic science – analyse paint etc. ieft at the scene of a crime and identify its source. ● Analyse the food colourings put in food to make sure only those permitted are present. ● How would you use chromatography to prove if an ink was a mixture or one pure colour? Separation Techniques

● DIstillation – a method of separating by evaporating condensing the vapour. e.g seawater. ● What is condensation? ● How does the condenser work? ● Could you separate two liquids like alcohol and water by distillation? ● It you could why would it be possible? Separation Techniques

Pure substance (2) Filtration (3 everyday examples) + exp. Separate soil+water by filtration + diagram. Evaporation + exp. Separate a mixture salt +water + know diagram Distillation + exp. Separate water from sea-water + know diagram Chromatography +exp. Separate ink dyes + know diagram. How it works (3) Uses (3) What you need to know in this section

● DIstillation – a method of separating by evaporating condensing the vapour. e.g seawater. ● What is condensation? ● How does the condenser work? ● Could you separate two liquids like alcohol and water by distillation? ● It you could why would it be possible? Separation Techniques