Distillation: L9 PDF

Distillation  When evaporation is used to separate pure water from saltwater, the salt is left behind as crystals. If it is more important to collect the solute than the solvent, this process of separation is called crystallisation. Table salt is produced by the process of crystal...

Distillation  When evaporation is used to separate pure water from saltwater, the salt is left behind as crystals. If it is more important to collect the solute than the solvent, this process of separation is called crystallisation. Table salt is produced by the process of crystallisation, using energy from the Sun to evaporate water from salt lakes.  Copper sulphate crystals obtained by slow evaporation- leaving the solution exposed to the air over 3 days (rather than using a Bunsen burner) There are many crystal kits you can buy to use at home  There are also lots of websites to learn more about growing crystals You can grow sugar crystals, alum crystals, borax crystals, table salt crystals, Epsom salt crystals https://thestemhub.org.uk/stem-at-home/item/grow-your-own- crystals https://www.wikihow.com/Grow-Alum-Crystals https://www.otago.ac.nz/chemistry/outreach/crystals/growing/  Imagine being stranded on a small, sandy island with no fresh water to drink. You can’t drink the sea water; it is salty and would dehydrate you even further. What can you do?  Sea water is a solution. Decanting and filtration won’t work — the dissolved salt particles are too small, they are dissolved in solution and do not form a sediment  We have already separated a mixture of salt and water. We evaporated the water to leave behind the salt But what if we want the water? How can we separate a solution of saltwater to obtain pure water? Distillation Distillation is a method for separating the solvent from a solution. For example, water can be separated from saltwater solution by distillation. This method works because water has a much lower boiling point than salt. When the solution is heated, the water evaporates but we use equipment which captures the water vapour. The gaseous water is then cooled and condensed back into liquid water which is collected in a separate container. The salt does not evaporate and so it stays behind. Simple distillation Simple distillation works because the dissolved solute has a much higher boiling point than the solvent. When the solution is heated, solvent vapour leaves the solution. It moves away and is cooled and condensed. Distillation Distillation Distillation Distillation  In the laboratory, pure water can be produced by a process called distillation. Saltwater is poured into the boiling flask (distillation flask) and heated to the boiling temperature for water, 100 °C. The water evaporates and becomes steam. The steam travels along the water condenser. The steam inside the condenser is cooled to below 100 °C and condenses to form liquid water. The condenser is kept cool by running cold water through its outer jacket by connecting it to a cold tap. The pure water collected in the conical flask is the distillate and this is how we make distilled water. The impurities in the water and the salt are left behind in the boiling flask.  Crystallisation and Distillation notes Explain how you can use sugar and water to make a sugar solution and then get back crystals of sugar. Include the words dissolving and evaporating. Label a diagram of distillation apparatus Explain how distillation can be used to separate and collect pure water from seawater. Use dot points or write a paragraph. Include these terms: boiling, evaporating, cooling, condensing as well as naming parts of the equipment.  Boss head + Round bottomed flask Jacket/ vapour vapors solution in from tap Conical flask distillate Retort stand Fractional distillation Fractional distillation is a method for separating a liquid from a mixture of two or more liquids. For example, liquid ethanol can be separated from a mixture of ethanol and water by fractional distillation. This method works because the liquids in the mixture have different boiling points. When the mixture is heated, one liquid evaporates before the other. Pure ethanol boils at 78°C and pure water boils at 100°C. Distillation and alcohol Distillation is also used when making spirits- alcoholic drinks with a high alcohol content. Distillation vaporizes the ethanol (alcohol) first as it has a lower boiling point. Leaving the water behind (which has a higher boiling point) Collecting the pure ethanol allows it to be further modified to make a high alcohol content drink or spirit  The higher percentages of alcohol in spirits like vodka, rum and whiskey are obtained by distillation. Wine and beer are not distilled.  You can often visit distilleries Eg the four pillars gin distillery in Healesville  Fractional distillation can be used to make essential oils and perfumes. Here lavender oil is being extracted.  Using rose petals to make perfume Crude oil  Crude oil Fractional distillation is used to separate crude oil into simpler, more useful mixtures. This method can be used because different hydrocarbon compounds in crude oil have different boiling points. Heated crude oil enters a tall fractionating column, which is hot at the bottom and gets cooler towards the top Vapours from the oil rise through the column Vapours condense when they become cool enough Liquids are led out of the column at different heights  https://www.youtube.com/watch?v=PYMWUz7TC3A Fractional Distillation | Organic Chemistry | Chemistry | FuseSchool 4 min  Fractional Distillation notes 1. Explain how fractional distillation can be used to separate a mixture of ethanol and water. State which liquid will be collected first. 2. State two commercial uses of distillation. 3. How is crude oil formed and where is it naturally found? 4. Why does petrol come out of the fractionating column higher up than diesel?