--- marp: true theme: default html: true --- # Filtration and evaporation Year 7 Chemistry · Pure substances and mixtures --- ## Today **We are learning to** filtration separates a solid that hasn't dissolved; evaporation recovers a solid that has. Describe both, name the residue and filtrate, and choose the right one. - I can describe how filtration and evaporation are done, in the right order. - I can name the residue and the filtrate. - I can choose filtration, evaporation or both for a mixture, and say why. --- ## Why it matters > How do you get clean salt back out of sandy salt water? Two techniques, in the right order: filtration takes out what didn't dissolve, and evaporation takes the water away from what did. --- 💬 Discussion ## Engage: predict **Sandy salt water is poured through filter paper. What stays in the paper?** - Sand only - Sand and salt - Nothing - Salt only --- ✍️ Activity ## Explore it {{embed: https://studio.learningwaypoints.com/tutorials/_playground-science/index.html?id=deck%2Fscience%2Fchemistry%2Ffilter-evaporate%2Fstep-2&code=widget%3A+filter%0A}} [Open this step in the tutorial](https://studio.learningwaypoints.com/tutorials/science/chemistry/filter-evaporate/?full=step-2#step-2) --- ✅ Check ## What happened? * Sand only. Dissolved salt particles are small enough to pass through with the water, and come back when the water evaporates. --- ✅ Check ## Filtration **Put the filtration steps in order.** ```science Pour the mixture in slowly Put the cone in a funnel over a beaker Leave the solid (the residue) in the paper Let the liquid (the filtrate) drip into the beaker Fold the filter paper into a cone ``` --- ✅ Check ## Evaporation **Put the evaporation steps in order.** ```science Stop heating when most of the water has gone Let the rest evaporate to leave crystals Heat it gently Pour the filtrate into an evaporating dish ``` --- ✅ Check ## Why each works **Filtration can't get the salt out of salt water, but evaporation can. Why?** - Heating destroys the water and leaves the salt - Dissolved salt has disappeared, and heating makes it come back - Dissolved salt particles are small enough to pass through the paper, but when heated only the water particles escape, because water boils far below salt - Salt is heavier than water, so it sinks while the lighter water rises away * Answer: Dissolved salt particles are small enough to pass through the paper, but when heated only the water particles escape, because water boils far below salt --- ✅ Check ## Mix it up **Looking back at pure substances and mixtures: before it is filtered, is sandy salt water a pure substance?** - No, because it looks cloudy - Yes, because the salt has dissolved - Yes, because it is all water - No: it has three kinds of particle (water, salt and sand), so it is a mixture * Answer: No: it has three kinds of particle (water, salt and sand), so it is a mixture --- ✍️ Activity ## which technique? {{embed: https://studio.learningwaypoints.com/tutorials/_playground-science/index.html?id=deck%2Fscience%2Fchemistry%2Ffilter-evaporate%2Fstep-5&code=widget%3A+quiz%0Aneed%3A+6%0Aoptions%3A+Filtration%3Dfilter%3B+Evaporation%3Devap%3B+Filter%2C+then+evaporate%3Dboth%3B+Neither%3Dneither%0Aitem%3A+Sand+and+water.+Get+the+sand.+%7C+filter+%7C+Sand+doesn%27t+dissolve%2C+so+filter+it+out.%0Aitem%3A+Salt+water.+Get+the+salt.+%7C+evap+%7C+Salt+is+dissolved%2C+so+it+passes+through+a+filter.+Evaporate+the+water+away.%0Aitem%3A+Sand%2C+salt+and+water.+Get+the+salt.+%7C+both+%7C+Filter+out+the+sand+first%2C+then+evaporate+the+filtrate.%0Aitem%3A+Chalk+dust+in+water.+Get+the+chalk.+%7C+filter+%7C+Chalk+doesn%27t+dissolve.%0Aitem%3A+Copper+sulfate+solution+%28blue%29.+Get+the+copper+sulfate.+%7C+evap+%7C+It+is+dissolved%2C+so+evaporate+to+leave+crystals.%0Aitem%3A+Iron+filings+and+sand%2C+both+dry.+Separate+them.+%7C+neither+%7C+There+is+no+liquid.+Use+a+magnet.%0Aitem%3A+Tea+leaves+in+tea.+Get+the+drink+without+the+leaves.+%7C+filter+%7C+The+leaves+don%27t+dissolve.+A+strainer+is+a+filter.%0Aitem%3A+Sugar+dissolved+in+water.+Get+the+sugar.+%7C+evap+%7C+Sugar+is+dissolved.+Heat+gently%2C+as+sugar+burns+easily.%0Aitem%3A+Muddy+salt+water.+Get+the+salt.+%7C+both+%7C+Filter+out+the+mud%2C+then+evaporate.%0Aitem%3A+Oil+floating+on+water.+Separate+them.+%7C+neither+%7C+Both+are+liquids.+Let+them+settle+and+pour+off+the+top+layer.%0A}} [Open this step in the tutorial](https://studio.learningwaypoints.com/tutorials/science/chemistry/filter-evaporate/?full=step-5#step-5) --- ✅ Check ## The procedure **You have a dry mixture of sand and salt. Order the steps to end up with dry sand and salt crystals, separately.** ```science Collect the salt crystals Rinse the sand in the paper with a little clean water, then leave it to dry Filter the mixture Gently evaporate the filtrate, rinse water included Add water to the mixture and stir until the salt dissolves ``` --- ✅ Check ## Through the paper **During filtering, which particles pass through the paper?** - All the particles - Only water particles - Water and salt particles * Answer: Water and salt particles --- ✅ Check ## Out of the dish **During evaporation, which particles leave the dish?** - Only water particles - Water and salt - Only salt * Answer: Only water particles --- ✅ Check ## Elaborate: out in the world **Filtration or evaporation?** Groups: Filtration · Evaporation A coffee machine holds the grounds in a paper cone. · Shallow sea-salt ponds are left in the sun for weeks. · A pool pump pushes water through a sand or cartridge filter. · Wet clothes on a washing line dry out. * Answer: A coffee machine holds the grounds in a paper cone. → Filtration; Shallow sea-salt ponds are left in the sun for weeks. → Evaporation; A pool pump pushes water through a sand or cartridge filter. → Filtration; Wet clothes on a washing line dry out. → Evaporation --- ✅ Check ## Elaborate: First Nations separation techniques **Which property difference does each technique use?** Groups: Some parts are lighter than others · Some parts are bigger or look different · Different boiling points Winnowing: seeds are tossed in a coolamon so the breeze carries the husks away. · Yandying: the coolamon is rocked in a rhythm so seeds and heavier grit move to different parts of the dish. · Hand-picking: sticks and stones are picked out of the seeds by hand. * Answer: Winnowing: seeds are tossed in a coolamon so the breeze carries the husks away. → Some parts are lighter than others; Yandying: the coolamon is rocked in a rhythm so seeds and heavier grit move to different parts of the dish. → Some parts are lighter than others; Hand-picking: sticks and stones are picked out of the seeds by hand. → Some parts are bigger or look different --- ✅ Check ## Pattern **What is the pattern in the results?** - Finer paper gives a clearer filtrate but takes longer - Coarser paper is better in every way - There is no pattern * Answer: Finer paper gives a clearer filtrate but takes longer --- ✅ Check ## Clearer **Why is the fine paper's filtrate clearer?** - The water goes slower, so the mud is lighter - It soaks up the mud - Its smaller holes trap smaller mud particles * Answer: Its smaller holes trap smaller mud particles --- ✅ Check ## Slower **Why does the fine paper take longer?** - The water gets heavier - The fine paper soaks up more of the water - Smaller holes let less water through each second * Answer: Smaller holes let less water through each second --- ## Evaluate: look back What did you think would stay in the filter paper? Write one sentence: "At first I thought… Now I think… because…" **Revision summary** - Filtration separates an undissolved solid from a liquid. The solid left in the paper is the **residue**; the liquid that passes through is the **filtrate**. - It works because the solid's particles are too big for the holes. Dissolved particles pass straight through. - Evaporation separates a dissolved solid from the liquid: the liquid's particles escape as a gas; the solid's particles stay and form crystals. - For a solid that dissolves plus one that doesn't: filter first, then evaporate the filtrate. --- ✅ Check ## Exit ticket **In filtering sandy salt water, what is the residue and what is the filtrate?** * The residue is the sand left in the paper; the filtrate is the salt water that passes through.