Separating mixtures: rock salt What happens to sugar cube when you drop it into your tea? Try to draw a particle diagram to explain this? LO: to separate mixtures that dissolve and don’t dissolve in water
Dissolving things – some definitions If a substance CAN be dissolved it is called __________ If a substance CANNOT be dissolved it is called _________ A solvent with an insoluble substance is called ___________ Words – soluble, solute, solvent, solution, insoluble, suspension
7H Mixtures and solutions - Is it pure or is it a mixture? A pure substance contains just one type of particle. A mixturecontains at least two different types of particle. A liquid can be pure or a mixture. Which of these liquids is a mixture? It’s a trick question – they’re all mixtures! Do you know why?
Planning an experiment: You have a beaker full of rock salt (sand and salt). You want to separate the mixture so you have only salt. Look at the diagrams below and use them to write a step by step method explaining how to separate salt from rock salt. Show your method to Ms. Lee, then you can start the practical
Weigh 5 spatulas of rock salt before you begin? • Crush the rock salt using a pestle and mortar? 3) Put the crushed rock salt in to a beaker and add 25cm3 of water 4) Filter the mixture through the filter paper into the conical flask 5) Put salt solution into evaporation basin and heat it on gauze? QUESTIONS 1.Why did you filter the mixture and what is left in the beaker after filtering? 2.What will be left in the basin? 3. Complete pages 93-95 theory book1
Evaporation and filtration • In this practical we tried to separate rock salt – a mixture of ____ and sand. To do this we followed four steps: • We ground the rock salt using a ______ and mortar, • We dissolved the mixture, • We _________ it, • We evaporated the remains. • The sand didn’t _________, so we were able to filter it out. The salt did dissolve, so we had to ________ the remains to get the salt back. Conclusion: Filtration can be used to remove something that doesn’t dissolve and evaporation can be used to separate something that does dissolve. Words – filtered, salt, pestle, evaporate, dissolve
Plenary • Go to lab to look at particle posters