Separating Substances D. Crowley, 2007

Separating Substances To know how to separate substances Friday, February 05, 2016

Key Terms Name the following: - SoluteSolventSolution - the mixture formed when a substance dissolves in it - the substance that dissolves - the liquid in the solution - mixing of a substance in a liquid - a substance which can dissolve (mix in a liquid) - a substance which cannot dissolve (mix in a liquid) Solution Solute Solvent Dissolve Soluble Insoluble Solution Solute Solvent Dissolve Soluble Insoluble

Accident Transport company set to lose millions… Yesterday a large truck crashed on the Marchwood Bypass shedding its load in the road – a representative from the transport company commented ‘this is a catastrophe! The truck was carrying a large amount of sand, salt and iron, all destined for different companies… We do not know how we are going to fulfil these orders unless we are able to separate the mixture – if we fail to do this, we will lose an enormous amount of money!’

Accident How could you help the company separate the sand, salt and iron – consider this in your groups…

Filtration How does filtration work? Can you and your partner come up with a good explanation? Filtration can separate in insoluble solid (does not dissolve) from a liquid

What if its dissolved? Some solids dissolve in liquids (soluble) – others, such as sand, are not (insoluble) What could we do to separate something which has dissolved - e.g. salt from water? Say we were stuck on a ship, out at sea, and we ran out of water - how could we get some fresh drinking water?

Dissolved Why can’t we use filtration for salt and water? Think about the particles, and what happens to them when they dissolve The salt has dissolved - its particles are thoroughly mixed, so they will just pass straight through our filter paper… Think about the Dead Sea - remember this has a very high salt level Rivers flow into it, but none flow out - the salt level increases, but the water level stays pretty constant - so where is the water going, and by what means?!

Evaporation The Dead Sea is so salty because no rivers flow out of it. This means, that when the water evaporates, the salt is left behind Evaporation can be really useful - remember its where a liquid changes into a gas Water can be evaporated, leaving our solute behind (the salt)

Risks Before you complete this experiment, we need to consider the risks Using your risk assessment, think about the apparatus we are going to be using, and write in the risks and action to be taken…

What will you do? Tick which equipment you will need Explain how you are going to carry out your experiment - how you will separate the sand, salt, iron and water? And finally, draw the equipment you are going to use for the corresponding experiment

Experiment Remember all the safety rules we follow during an experiment… Be as accurate as possible! The group with most sand + salt + iron separated will be the winners Salt pileSand pileIron pile

Review How did the filtration separate the sand and water? How did the evaporation separate the salt and water? Why would filtration not separate salt from water? Why did the magnet remove the iron but not the salt or sand?

Filtration Filtration works because the filter paper will stop the insoluble solid from passing through it - this makes it nice and easy for us to collect! The filter paper can easily catch the insoluble sand

Evaporation Evaporation helps us separate because some water particles are given enough energy to escape the attraction of the other particles. If we heat the water for a long enough, eventually all our particles are given enough energy to escape, just leaving salt Salt cannot be separated using filtration, because the particles are too well mixed - this means that they would pass straight through the filter paper The filter paper cannot catch the soluble salt, as the particles are too well mixed

Magnetism Only some metals are magnetic, allowing this method to separate our iron from the other substances…

Levels Level 4 – the student draws a diagram and simply explains what has happened Level 5 – the student draws a diagram using the correct symbols and explains filtration and evaporation using the correct scientific terms Level 6 – the student draws and labels a diagram using the correct symbols and using a ruler and pencil. The student also explains filtration and evaporation using a particle model