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Separations

Separations. Magnets Settling Decanting Filtering Evaporation Distillation Chromatography. Writing Down Results. When you do a scientific investigation make sure you WRITE DOWN your RESULTS. Magnets. What types of materials will magnets attract?.

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Separations

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  1. Separations Magnets Settling Decanting Filtering Evaporation Distillation Chromatography

  2. Writing Down Results When you do a scientific investigation make sure you WRITE DOWN your RESULTS.

  3. Magnets What types of materials will magnets attract? How could you separate a mixture of sulfur and iron filings? Magnets will attract IRON, STEEL (NICKEL and COBALT as well). By using a MAGNET! Separating iron and sulfur 1. Your teacher will give you a mixture of iron and sulfur and a magnet. 2. Wrap the magnet in a paper-towel. 3. Use the magnet to separate the iron filings from the sulfur. Questions 1. What did you observe? 2. Could you use a magnet to separate gold and sulfur? The iron filings are attracted to the magnet. No, gold is not magnetic.

  4. Exercise 1: Describe How You Could Use a Magnet to Separate some Steel Coins from some Copper Coins

  5. Settling Separating sand and water 1. Fill a beaker with water. 2. Add some sand to the water. 3. Stir the sand using a glass rod. What do you observe? 4. Wait a couple of minutes. What can you see now? What happened? The sand particles are pulled to the base of the beaker by GRAVITY. Extension activity Repeat the experiment above but instead of just sand use a mixture of sand and gravel. What do you observe?

  6. Decanting Separating sand and water 1. Take a beaker containing water with sand settled at the bottom. 2. Carefully pour away the water whilst trying not to disturb the sand. 3. How clean is the water you have poured off (decanted)? Is there a better method of separating sand and water? It is very difficult using the decanting method to obtain pure water that contains no sand particles. There is a better way of separating sand and water, we will look at that next.

  7. Filtration By using FILTER PAPER. Filter paper contains small holes that will let liquids pass through but not insoluble solids. Separating sand and water 1. Your teacher will give you a mixture of sand and water. 2. Set up the apparatus as shown on the right. How could you use a similar method to separate sand and water? If you have cooked some pasta in a pan at home, how do you separate the water from the pasta? By using a sieve! 3. Take a piece of filter paper and fold it in half, then fold it in half again. 4. Open up a ‘pocket’ in the filter paper and place it in the filter funnel. 5. Carefully pour the mixture of sand and water through the filter paper. 6. Note your observations.

  8. Exercise 2: Filtrate and Residue Residue 1. Which substance was left on the filter paper (this is called the RESIDUE)? 2. Which substance passed through the filter paper (this is called the FILTRATE)? 3. Could you use the filtration method to separate salt and water? The sand was the residue. Water was the filtrate. No, salt is soluble in water and would therefore pass through the filter paper with the water. Filtrate

  9. Evaporation When wet clothes are left on a washing line they eventually become dry. Why? If you heat a solution of salt and water and then leave it for a few days the water will EVAPORATE and leave the salt behind. How could you use a similar method to separate salt and water? The water on the clothes evaporates (changes from a liquid into a gas). Separating salt and water 1. Your teacher will give you a solution of salt and water. 2. Set up the apparatus as shown on the right. 3. Pour some of the solution into the evaporation dish. 4. Place the evaporation dish onto the gauze. 5. Heat the solution for 30 seconds using a blue Bunsen flame. 6. Let the evaporation dish cool and then leave in a safe place for a few days. 7. After a few days note down your observations.

  10. Evaporation You can separate a soluble solid from a liquid using evaporation. When a liquid evaporates it changes into a gas. If a solid is dissolved in the liquid, when the liquid evaporates the solid is left behind. If you heated some water that had salt dissolved in it, then the water would evaporate leaving behind crystals of salt. If you go swimming in the sea on a sunny day, evaporation can cause salt crystals to be left on your skin.

  11. Exercise 3: Evaporation Results 1. What was left behind in the evaporation dish after a few days? 2. Where did the water go to? 3. Could you use this method to collect water? Crystals of salt. It evaporated (changed from a liquid to a gas) and went into the air. No, if you wish to separate salt and water, whilst collecting both substances you would need to use another method.

  12. Exercise 4: Plan an Investigation Your task is to plan an experiment that will allow you to separate a mixture of soot and copper sulfate. You will then perform your investigation. Soot is a substance that is insoluble in water. Copper sulfate is a substance that is soluble in water. You must be able to collect the soot and the copper sulfate. You can use any standard laboratory apparatus you may require.

  13. Distillation Separating salt and water 1. Your teacher will give you a solution of salt and water. 2. Set up the apparatus as shown below. Leibig Condenser 3. Add some of the solution into the flask. Delivery tube 4. Fit the delivery tube and bung into the conical flask. 5. Heat the solution using a blue Bunsen flame. 6. Note your observations. Bung Distillate

  14. Exercise 5: Distillation 1. At what temperature does water boil? 2. What was left in the conical flask at the end of the experiment? 3. In the delivery tube, boiled water condenses, what does the word condense mean? 100ºC Salt A gas changes into a liquid Research homework 1. What does the Leibig condenser do? 2. Find out two uses of distillation in industry.

  15. Chromatography 1. Take a piece of filter paper and draw a large dot in the middle with a coloured felt-tip pen. 2. Then using a dropper add a couple of drops of water onto the ink dot. 3. Write down what you observe. What did you observe? The ink drop separates out into colours. The pattern you get depends upon the colour of felt-tip pen you use.

  16. Exercise 6: Chromatography • 1. Four coloured felt-tip pens produce the ink patterns below. • a) Which ink dot contains only one colour? • b) Which ink dot contains three colours? • c) Which two ink dots contain two colours? A D B & C

  17. Exercise 7: Link the Separation Techniques Chromatography Iron and sulfur Evaporation Sand and water Distillation Ink from water Filtration Salt from water Colours in brown ink Magnet

  18. Exercise 8: Write a Sentence about Each of the Words Below Pouring off the liquid leaving the solid behind Decanting Letting gravity pull the solid particles to the bottom of a liquid Settling Using filter paper to separate an insoluble solid from a liquid Filtering Using heat to change a liquid into a gas, leaving a soluble solid behind Evaporation Using water to separate colours Chromatography

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