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# Filtration and Crystallisation **Learning Objectives:** * Describe these experimental techniques for the separation of mixtures: * Filtration * Crystallisation **Starter:** **Correct the incorrect statements.** * Ionic bonding occurs between a metal and a non-metal. * Mg has a giant m...

# Filtration and Crystallisation **Learning Objectives:** * Describe these experimental techniques for the separation of mixtures: * Filtration * Crystallisation **Starter:** **Correct the incorrect statements.** * Ionic bonding occurs between a metal and a non-metal. * Mg has a giant metallic structure. * Diamond has a high melting point because it has many strong covalent bonds to break. * CO2, H2O, NH3 are all examples of simple molecular structures. * Graphite can conduct electricity because it has delocalised electrons between the layers of its structure. * Ionic compounds can conduct electricity when molten or dissolved in water because the ions are free to move. **Filtration:** * Filtration is a separating technique that separates an insoluble solid from a liquid (this can either be a pure liquid or a solution). * It works because filter paper has tiny holes that allow liquids to pass through, but not solids. * The liquid passes through the filter paper and becomes the filtrate. * The solid remains behind on the filter paper and becomes the residue. **(Diagram of Filtration):** ``` filter paper / \ / \ | | | | | | funnel conical flask | | / \ / \ / \ / \ residue filtrate ``` **Crystallisation:** * Crystallisation involves heating a solution until it becomes saturated. * This means that no more solid can dissolve in it at that temperature. * Crystals of the solute will start forming so we let the solution cool down and the solubility decreases, so more solute crystals will form. * Leave the rest of the solvent to evaporate and then put the crystals in an oven to dry. **(Diagram of Crystallisation):** ``` evaporating basin / \ / \ | | copper sulfate solution | | | | boiling water-----> Bunsen burner ```