science education teaching booklet

Name: _________ Most substances we find on Earth are mixtures. Separating mixtures is important because there are many uses for the new substances that are produced, for example, petrol is separated from crude oil and used widely in our society. A pure substance consists of only one type of particle. A pure substance becomes impure when it has at least a small amount of another substance mixed in with it. This other substance is called an impurity. Mixtures are made of two or more substances mixed together. Special techniques such as filtering and crystallising are used to separate mixtures. Sometimes we need to make mixtures instead of separating them. Glass, paint, concrete and food are examples of useful mixtures. All substances can be divided into two groups, pure substances and mixtures. Pure substances Mixtures Pure substances cannot be split into different parts. They are made up of chemicals that all act the same. Copy the following information into these two shapes. Mixtures can be split into different parts. They are made up of different substances that can be easily separated because they act differently. Chemical and physical changes In a chemical reaction, new substances are formed. Chemical reactions are usually detected by colour changes, bubbles of gas, the formation of a precipitate (solid) or a change in the temperature of the mixture. In a physical change, no new substances are formed. These changes are easily reversed by, for example heating or cooling. 2 In the diagrams below, the different shapes in the boxes stand for different types of particles. A pure substance has only one sort of shape. A mixture has two or more different shapes. Write under each box whether you think it is a pure substance or a mixture. That’s my kind of mixture What puts the fizz, in drink? Like most substances, fizzy drinks are mixtures. If you look at the label on a bottle or can of soft drink you will see that it contains sugar, food colouring, flavouring, preservative and carbon dioxide dissolved in water. A mixture of one substance dissolved in another is called a solution. The substance in which the chemicals can dissolve is called the solvent. The substances that dissolve in a solvent are called solutes. Water is a good solvent because many chemicals can dissolve in it. A solute dissolved in water is an aqueous solution. There are other solvents that form non-aqueous solutions. The preservatives in soft drink stop the drink from going bad. Flavourings make the drink taste more pleasant and food colouring makes the drink more attractive to look at. The 'fizz' in fizzy drinks is carbon dioxide gas. The manufacturers pump the gas into the bottles or cans at high pressure and seal the containers. This keeps the gas dissolved in the solution. When you open the drink the pressure is reduced and the carbon dioxide gas bubbles out of the solution In the passage above some very important scientific terms have been used, in your own words explain what the bolded terms mean. DISSOLVED: __________________________________________________________________________________________ __________________________________________________________________________________________ SOLUTION: __________________________________________________________________________________________ __________________________________________________________________________________________ 3 SOLVENT: __________________________________________________________________________________________ __________________________________________________________________________________________ SOLUTES: __________________________________________________________________________________________ __________________________________________________________________________________________ Solutions and suspensions Solutions consist of mixtures in which the solute particles are so small that they remain spread throughout the solvent. They cannot be filtered and do not settle out to form a sediment. Suspensions consist of mixtures in which the particles are so large that they can be filtered out of the mixture. They settle out to form a sediment. Colloids Colloids are mixtures that contain particles that are larger than the particles in a solution but smaller than those in a suspension. If you shine a light through a colloid some of the light will be reflected back to your eyes by the tiny particles floating in it. Light will pass straight through a solution. Colloids are different from suspensions because the particles in a colloid do not settle out. Also, the particles in a colloid can pass through a filter. The particles in a colloid may be solid grains, liquid droplets or gas bubbles. The material in which they are spread out may also be solid, liquid or gas. Four common types of colloids are gels, aerosols, foams and emulsions. Emulsions A colloid in which tiny droplets of one liquid are spread evenly throughout another liquid is called an emulsion. Because the particles in an emulsion cling together, individual particles do not settle out. Ointments and cosmetic creams are emulsions. Margarine and some dairy products, including homogenised milk and butter, are emulsions of oil and water. SEPARATING MIXTURES Sometimes you need one substance from a mixture but not the other. For example, you might want to get the salt from salt water. To separate the parts of a mixture you have to find a difference in properties. Maybe one of the substances in the mixture dissolves in water and the other does not. Maybe one is attracted to a magnet and the other is not. Or maybe they boil at different temperatures Sieving The muffin recipe says 'add the sugar and sultanas separately' but you have mistakenly mixed them. Now you need to separate them before you can continue making the muffins. What is the easiest and quickest way to do this? Using a sieve will allow the smaller grains of sugar to pass through the holes and retain the sultanas. In refining metals from their ores large screening sieves are often used to separate small chunks of ore from larger ones which require further crushing; in quarries the material is graded by screening to provide different size pieces of rock for different purposes such as road building and concrete mixing. 4 Decanting Sometimes you may want to separate an insoluble solid substance which is mixed with a liquid, for example a bottle of red wine which contains sediment. Decanting is a method you can use to roughly separate the liquid from the solid. To do this, allow the solids to settle to the bottom of the bottle then gently pour the liquid off the top, trying not to shake the bottle. This will leave the sediment in the bottom of the bottle. Gravity separation Gold panning is a well known example of gravity separation. A stream of water is used to move the lighter particles of sand away from the heavier gold particles. Filtration Chalk can be separated from water by pouring the suspension through filter paper, as shown in Fig. The chalk stays in the filter paper, and the water passes through. (The filter paper has tiny holes in it. The water passes through these holes, but the chalk cannot.) In our day-to-day life we use filters to separate solids from liquids and gases. For example, vacuum cleaners have special bags that filter dust and dirt from the air drawn in. The hairs in your nose are used to filter the dust from the air you breathe. There are filters in a car to clean the petrol, air and oil. Filters are used to purify the water we drink, and to clean the water in swimming pools. Filtering equipment This drawing shows how you can set up some equipment in the laboratory to filter liquids. Use the words in the list to label the diagram. 5 In this space make a science diagram of the drawing. Use your pencil and ruler. Then label your diagram The diagram below shows you how to fold a filter paper. Try this for yourself and paste your filter paper into the space provided below. Paste Here 6 Filtration Experiment AIM To separate a suspension of insoluble copper carbonate and water. MATERIALS • 150 ml conical flask • Filter paper • Stirring rod • Filter funnel • Test-tube half-filled with water and a teaspoonful of copper carbonate METHOD 1 Set up your filtration equipment as shown. 2 Carefully filter your suspension of copper carbonate and water. Be sure you don't poke a hole in the filter paper with the stirring rod. 3 Record your observations about the liquid in the conical flask, the filtrate, and the residue in the filter paper. RESULTS __________________________________________________________________________________________ __________________________________________________________________________________________ __________________________________________________________________________________________ __________________________________________________________________________________________ DISCUSSION 1 How effective was your separation? __________________________________________________________________________________________ __________________________________________________________________________________________ How could this experiment be modified so that you can determine exactly how accurate your separation technique is? __________________________________________________________________________________________ __________________________________________________________________________________________ 2 ACTIVITY Our young scientist is filtering a mixture of chalk dust and water. 1. 2. What will collect on the filter paper? _________, this will be solid, and is called residue. What will collect in the beaker? _____________, this will be liquid, and is called filtrate. 7 In this diagram, our scientist filtered a red liquid that was mixed with charcoal. The charcoal did not dissolve in the red liquid. 3. What was the residue? Was it the charcoal or the red liquid? __________ 4. 5. Label this on the diagram. What was the filtrate? Was it the charcoal or the red liquid? __________ 6. Label this on the diagram and colour the red liquid on the diagram. 7. Complete the table below to show which machine separates which substances. Write in each box whether the substances are solids, liquids or gases. The first line has been done for you. Machine Vacuum cleaner Separates Which is a solid/liquid/gas Solid From Which is a solid/liquid/g as Gas Dust D Air Petrol filter Food strainer F Sink strainer F S Fly screen F Using a centrifuge A machine designed to separate mixtures by a spinning motion is called a centrifuge. A spin-drier is one type of centrifuge. Centrifuges are used to separate the parts of a suspension. For example, blood contains red blood 8 cells and other things suspended in a liquid called plasma. The heavier red blood cells can be separated from the plasma using a centrifuge. Cream can also be separated from milk using a centrifuge. In a sugar mill the sugar crystals are separated from the syrup using a centrifuge. A cylinder with holes in it is spun at high speed. The liquid syrup spins off through the holes, leaving the solid sugar behind. ACTIVITY The instructions for a new centrifuge came on cards, but the cards were dropped and got mixed up in the wrong order. See if you can write the correct instructions from the boxes under each of the diagrams The precipitate will have settled to the bottom of the test tube. Mix two chem icals together to make a precipitate Divide the precipitate evenly between two test tubes Wind the handle and spin the centrifuge, leaving room for the tubes to spin out freely. Stop winding and all ow the centrifuge to stop slowly. Place the two test tubes in the centrifuge in opposite holes. What is a centrifuge? Use the words in the list supplied to complete each of the following sentences: 1. 2. 3. You have all seen a washing machine S _________ This is a simple C ___________________ A centrifuge is simply a machine that S _________ things. SPINNING CENTRIFUGE SPINS CLOTHES WATER OUTWARDS HOLES 9 TUB ROUND 4. When the washing machine is spinning, it separates C _____________ and W ______________ . 5. 6. As the machine spins, the clothes and water are flung O_______________ The water escapes through H______________, while the clothes stay in the T______________ 7. You will notice that all centrifuges are the same shape: they are all R__________ . Evaporation Filtration cannot be used to separate the substances in a solution because the particles of the solute are small and pass through any filter paper. Evaporation is a process in which a liquid can be removed from a solution by using heat, leaving the solute behind. This is ideal for separating solutions which have very small particles that cannot be removed by filtration. Crystallisation Evaporating the water from the salt solution by heating is a very quick method of separating the solvent from the solute. Sometimes this is not a practical method to use as the quantities may be very large. In the production of salt for commercial use the heat of the sun is used to evaporate the water. The salt forms larger crystals because the evaporation is slow. This process is called crystallisation. 10 Crystallisation Experiment AIM To find out how much solid (solute) is dissolved in soft drink (solution). • • • • • • MATERIALS Bunsen burner tripod and gauze mat evaporating basin 50 ml of soft drink solution electronic balance safety glasses Use the balance to find the mass of the empty evaporating basin. Record this in your workbook. Carefully add the 50 ml of soft drink to the basin. Set up the Bunsen burner under the tripod and gauze. Then put on your safety glasses. Heat the basin until almost all of the water has evaporated. Leave the basin to stand so that the remaining water evaporates as the basin cools. Find the mass of the basin and its contents. Subtract the mass of the empty basin to find the mass of the solids dissolved in 50 ml of soft drink. Mass of basin after heating (B) METHOD 1 2 3 4 5 RESULTS Mass of empty Basin (A) Solid dissolved in soft drink = A – B Solid dissolved in soft drink = DISCUSSION 1 Describe the appearance of the solid material in the basin. __________________________________________________________________________________________ __________________________________________________________________________________________ 2 The solid material remaining in the basin is a mixture of substances. Suggest what might be in this mixture. __________________________________________________________________________________________ __________________________________________________________________________________________ 3 How much solid would be present in a 500 ml bottle of this soft drink? __________________________________________________________________________________________ __________________________________________________________________________________________ 11 ACTIVITY This diagram shows how we can evaporate water from a solution to allow the solid to crystallise out. Use the words in the list provided to label the diagram In this space make a science diagram of the drawing. Use your pencil and ruler. Then label your diagram . 12 Use the words in the list to complete each of the following sentences. 1. When the water E___________ the salt C____________________. 2. This shows that E________________ always occurs with C_____________________. 3. When a solid dissolves in a liquid, a S_____________________ is formed. 4. To crystallise the solid from the solution in the laboratory, the solution is placed in an E _____________ B ______________ . 5. The basin is H __________ gently. 6. The heat causes the W___________________ to evaporate, leaving the S_____________ S__________________ crystals in the dish. Use the words in the list to complete each of the following sentences about getting salt from evaporation. 7. Salt lakes are found in desert areas of Australia. They are formed when R___________ into lakes carry water which has S _________ dissolved in it. 8. In the dry season, the hot S __________ makes all the W __________ evaporate, leaving the S __________ behind. 9. The salt we buy in the supermarket comes from the ocean. S _________ is pumped into large S _________ P ________ and allowed to E __________. The salt is collected and packaged. Trucks transport the packaged salt to supermarkets. 10. After we buy the salt, we put it in a S __________ S __________. 11. Then we sprinkle it on our C ___________. SALT SHAKER RUNNING RIVERS SALTS EVAPORATE SUN WATER SALT SEAWATER SALT PANS CHIPS EVAPORATES CRYSTALLISES EVAPORATION CRYSTALLISATION SOLUTION EVAPORATING BASIN HEATED WATER SOLID SALT 13 Write the correct words in this flow diagram to show how the salt you sprinkle on your chips comes from the ocean. The size of crystals depends on how fast a solution cools. If it cools very fast, the crystals will be small. If the solution cools slowly, the crystals have time to grow very large. Our young scientist set a solution aside to cool and measured the crystals at different times. The table shows how big the crystals grew. Plot the size against the time so that you draw a line graph of her results Time to cool (hours) Size of Crystal (mm) 1 1 4 4 8 8 10 10 10 9 8 Size of crystals (mm) 7 6 5 4 3 2 1 0 1 2 3 4 5 6 7 8 9 10 14 Time to cool (hours) 12. Now use the your graph to find out what size crystals you would get after: a. Two hours __________ b. Six hours __________ c. Nine hours __________ 13. Make up a rule from the results of this graph: The longer the solution takes to cool, the L __________ the crystals will grow. Growing Crystals AIM To grow crystals of copper sulfate MATERIALS • copper sulfate crystals • hot water • two 250 ml beakers • cotton thread, pencil and plastic cling wrap METHOD 1 Prepare a saturated solution of copper sulfate in hot water in a beaker. How will you know when it is saturated? 2 Allow the solution to cool to room temperature so the excess solute settles to the bottom of the beaker. 3 Decant or filter the saturated solution into a clean beaker, making sure you remove all solids. 4 Suspend a thread from a pencil into the solution and cover the beaker with cling wrap to prevent dust settling in it. Store the beaker in a place where it will not be disturbed. 5 After a few days you will find some small crystals have formed on the thread. Remove all but the one with the most regular shape, replace the thread with this one remaining crystal (called the seed crystal) still on it, and every few days remove any small crystals which may have grown on the surface of the large one. DISCUSSION 1 How large was your crystal at the end of a fortnight? How large do you think your crystal could grow? __________________________________________________________________________________________ __________________________________________________________________________________________ 15 Froth flotation Used mostly in mining industry, some ore minerals (commonly copper) are separated from unwanted material by a process called froth flotation. While froth flotation makes use of special chemicals, this is a physical separation technique because it does not chemically alter the mineral. The crushed mixture is mixed with water and some special chemicals and stirred. Bubbles of air are blown into the bottom of the container and the copper ore is carried to the surface by the bubbles. The gangue sinks to the bottom of the tank and the copper ore is skimmed off the top of the liquid. The copper ore is then treated to extract the pure copper which can then be used to manufacture the many copper products we use. Magnetic Separation ACTIVITY Use the words in the list supplied to complete each of the following sentences. 1. The type of materials that are magnetic are made of I __________ . 2. Magnets can pick up objects made of I _________ and S _______ 3. In industry, permanent magnets are used to separate M __________ materials from N __________ materials. 4. Some non-magnetic materials are A __________ , P __________ and C_________. 5. Drop 10 paper clips in the grass and see how many you can find! IRON IRON STEEL MAGNETIC NONMAGNETIC ALUMINIUM PLASTIC COPPER 16 6. Complete the diagram below to show where each part of these different mixtures ends up. (Hint: It's a good idea to wrap your magnet in food wrap before you use it!) Fill in each of the labels. a. Paper clips and marbles b. Sand and iron filings c. Nails and toothpicks In many garbage dumps, materials are separated so that as many as possible can be recycled. The materials in these dumps are a mixture of plastics, metals, glass, aluminium, etc. Use the words in the list to find out how these materials are separated. 7. A huge magnet picks up all the M _________ materials, which are I___________ and S________________. 8. All the other materials are left behind. These are A _________ , P_____________ , G __________ and R ____________ . 9. Now label the diagram using the words in the list to show where you would find all these things MAGNETIC IRON STEEL ALUMINIUM PLASTIC GLASS RUBBER 17 1. Use words from the box to label the diagrams below. solute solution solvent sediment  suspension 2. Underline the correct word from the choices given in each sentence below. • A solute is dissolved in a solvent/solution. • Soluble/insoluble substances do not dissolve. • When an insoluble substance settles to the bottom of a liquid, it forms a suspension/sediment. • A mixture in which some or all of the particles settle out is called a solution/suspension. • A mixture in which the particles can be filtered out is called a solution/suspension. • A colloid/suspension is a mixture that contains particles that are larger than the particles in a solution but smaller than those in a suspension. • A colloid in which tiny droplets of one liquid are spread evenly throughout another liquid is called an emulsion/suspension. 3. Complete the table below. Separation method Sieving Decanting Gravity separation Magnetic separation Centrifuging List of examples • separating sediment from old wine • separating cream from milk • separating sugar from sultanas Example from list below Your own example • separating gold from sand • separating iron filings from sand 18 Application and uses of Science If you live in a large city or town there are two ways in which wastewater is removed from your home. Run off from rainwater on the roof and the garden goes into the storm water drain and flows directly into a river, bay or the ocean. It is generally left untreated so it is important that it should not contain chemicals or solid rubbish. Sewage comes from the wastes that we put down the drains in our kitchen, laundry, bathroom and toilet. These pipes are connected to the sewerage system. Sewage will contain a large quantity of water together with grease and dirt, paper, food scraps and human waste, a huge variety of things that must be removed before the water can be safely released back into the environment. There are a number of stages in the treatment of sewage. If the quantity is small, a septic tank can be used, but generally household wastes are treated at a larger sewage works. Sewage treatment at a sewage plant The stages in sewage treatment are: • floating solids and grease are removed using skimmers. • grit chambers remove inorganic solids and organic solids such as seeds—the sewage flows through these chambers so the organic matter doesn't settle. • fine solids are removed using screens with very small openings between 1.5 mm and 0.8 mm across, and by sedimentation. Many of the solids are very fine and suspended in the water, which can have air pumped through it to make them settle out. • the remaining effluent is pumped into a tank where it can be aerated or it can be sprayed over a trickle filter (a layer of rock) into the tank. Special bacteria in these aeration tanks feed off the material which is left, removing the last of the polluting matter. • the clean water is then discharged into the ocean or river. S ept ic tanks Houses which cannot be connected to a sewerage system have a septic tank to process the household waste. This tank is buried underground and waste disposing bacteria process the sewage. It is therefore important that no chemicals that may kill the bacteria are put down the drains. The clean water is piped out of the tank and allowed to drain through the nearby soil. As an extra precaution the water often passes through a series of sand filters to ensure it is free of pollutants. 19 Separating Liquid/Liquid Mixtures 1 Insoluble Separating funnel — When two separate liquids do not mix they often float in layers. It is easier to draw these layers off using a laboratory-separating funnel than by settling and pouring. Use the words in the list supplied to complete each of the following sentences 1. The separating funnel contains two L____________ that do not M___________. 2. There is a tap at the B_____________, so that when the liquid that is at the bottom of the separating funnel has run through into a beaker you can turn off the T______________ to stop the other liquid running through. 3. This method could be used to separate C____________ O_______ and W__________ or E_____________ 0________ and W_________. 4. Now label the diagram from the words in the list. LIQUIDS M IX BOTTOM TAP COOKING OIL WATER ENGINE OIL WATER 2 Insoluble Distillation is a way of getting pure solvent from a solution. It is the same process as evaporation, except that you catch the solvent after it evaporates. The apparatus shown below could be used to obtain pure water from salt water, for example. This is what happens: (a) The solution is heated in the flask. The solvent boils, and steam rises and passes into the condenser. The salt stays in the solution in the flask. (b) The condenser is cold, so the steam condenses to water. 20 (c) The water drips into the beaker. It is completely pure, and is called distilled water. Distillation can also be used to separate two or more liquids, e.g. alcohol and water. Oil refineries use distillation to separate crude oil into kerosene, petrol, oil and grease, which we use. Study the list opposite and choose a word to complete each of the following sentences. 1. The mixture of liquids is placed in the F__________. 2. The liquid with the lowest B_________P_____________ boils first. 3. Its V __________ moves through the C_____________ and changes back into a L_______________. 4. The liquid with the H___________ boiling point is left in the flask. 5. Now label the diagram from the words in the list. FLASK BOILING POINT VAPOUR CONDENSER LIQUID HIGHER THERMOMETER VAPOUR CONDENSER FLASK 21 What happens when you mix two different liquids? Study the list supplied and choose a word to complete each of the following sentences. 6. Some liquids M______ like A____ and W______ or P_________ and W_________. 7. Other liquids do not mix, like O________ and W__________. 8. If liquids do not mix, you will be able to see two clear L__________ , which means you can use a S_____________ F______________ to separate them. 9. If they do mix it is a lot harder to separate them, but if their B_________ P________ are different, we can use D______________ to separate them. MIX ALCOHOL WATER PETROL WATER OIL WATER LAYERS SEPARATING FUNNEL BOILING POINTS DISTILLATION Methods of distillation There are several ways to set up distillation in the laboratory. These diagrams show how we can use distillation to purify water. We call purified water distilled water. Study the diagrams and answer the questions below using the words in the list. 1. What is the solution heated in? F________________. 2. The solution can be heated by a B__________ B_________ or a H___________ P_________. FLASK BUNSEN BURNER HOT PLATE WATER VAPOUR CONDENSE AIR WATER JACKET WET CLOTH CONDENSER DISTILLED WATER 3. When water boils, it turns to steam. What is steam also called? W_________ V_________ 4. What is the word that means 'to turn back to water'? C _______________. 22 5. What three ways are used to cool the vapour? a. A__________ b. W_________ J___________ c. W_________C___________ 6. What is purified water called? D_____________ W________ 7. Colour in the diagrams using these colours: impure water = dark blue vapour = light blue purified water = white bunsen burner/hot plate = red water jacket or cloth = green Distillation of crude oil Crude oil is the term used to describe oil when it is removed from the ground. It is not a pure substance, but is made up of many different substances, or fractions (petrol, petroleum jelly, bitumen, etc.). These fractions can be separated out, or refined, using a special method of distillation called fractional distillation. The crude oil is heated to between 400°C and 500°C, which changes all the components into gases. The mixture of gases is pumped through a fractionating column (about 30 m high) and the various substances condense back to a liquid at different temperatures. As the top of the column is cooler than the bottom, and because the fractions have different boiling points, they can be pumped out at different heights. Crude oil from different parts of the world contains different proportions of the various fractions. Australian crude oil does not contain a high percentage of heavy fractions (heavy oil and bitumen) but does contain more of the lighter fractions. 23 Fractions such as petrol are usually found in only small proportions in any crude oil. More petrol can be obtained by breaking down heavy oil by heating it with steam to form lighter fractions (petrol and jet fuel). This process is called cracking. Propane, ethane and butane gas, which are used to make many plastics (e.g. polythene, PVC and polystyrene), are produced as by-products of the cracking process. A fractionating column. 1 When we refer to crude oil, what is a fraction? __________________________________________________________________________________________ __________________________________________________________________________________________ 2 Describe, in your own words, how crude oil is separated into fractions. __________________________________________________________________________________________ __________________________________________________________________________________________ 3 Using the information in the diagram above, draw a flow diagram to show the temperature at which each fraction is collected. __________________________________________________________________________________________ __________________________________________________________________________________________ 24 4 List two light fractions and two heavy fractions which can be separated from crude oil and briefly describe what you think each substance is used for. __________________________________________________________________________________________ __________________________________________________________________________________________ __________________________________________________________________________________________ __________________________________________________________________________________________ 6 Name three gases formed as by-products of cracking. What are these gases used for? __________________________________________________________________________________________ __________________________________________________________________________________________ Chromatography Different solids that are mixed together may sometimes be separated by a process called chromatography (khroma is Greek for colour). This involves dissolving them in a solvent and allowing the solvent to carry the solids along a strip of filter paper. The solids which dissolve the best in the solvent, or which grip onto the filter paper the least, will be carried the furthest along the filter paper. When the substances are different colours, it is easy to see the components of the mixture. Use the words in the list supplied to complete each of the following sentences. 1. Have you ever seen what happens to some P_______________ and I________________ on newspaper. 2. The ink S___________ through the paper. 3. This is also what happens in C______________________. 4. The chemicals will T_______________ through the paper 5. Have you ever tried different C________ inks or textas? 6. If you do you will find that each colour will spread out a D____________ amount, so you can S_____________ the colours if they are mixed together. 7. C_____________ can be used to separate very small amounts of different substances by allowing them to move slowly through paper, or even through a column of liquid. PAINTS INK SPREADS CHROMATOGRAPHY TRAVEL COLOURED DIFFERENT SEPARATE CHROMATOGRAPHY 25 The Smartie® Experiment Place a black Smartie® in the middle of a piece of filter paper. Add several drops of water onto it and leave it for half an hour. Now check what has happened. Use coloured pens or pencils to draw what colours you found were in the Smartie® in the circle provided. 8. Now list the colours in order from the outside to the inside of the circle. __________________________________________________________________________________________ __________________________________________________________________________________________ 9. Which colour moved the fastest? __________________________________________________________________________________________ __________________________________________________________________________________________ 10. Which colour moved the smallest distance? __________________________________________________________________________________________ __________________________________________________________________________________________ 26 Mixtures in Industry Alloys are mixtures of metals. They are useful because they have different properties from the metals they contain. The table shows some common alloys and the metals they contain. Use this information to answer the questions below. Alloy Bronze Brass Steel Stainless steel Duralium Magnalium Type metal Solder Pewter Sterling silver 22 carat gold 18 carat gold Tin (85%) Iron (99%) Percentage (%) of each metal Copper (92%) Tin (6%) Zinc (2%) Copper (70°/o) Iron (99%) Zinc (30°/o) Carbon (1%) Chromium (20%) Carbon (1%) Iron (75%) Nickel (5%) Copper (4%) Antimony (18%) Tin (50%) Aluminium (95%) Lead (72%) Manganese (1%) Tin (10%) Antimony (2%) Aluminium (70%) Lead (50%) Copper (7%) Silver (92.5%) Gold (92%) Gold (75%) Magnesium (30%) Bismuth (6%) Copper (7.5%) Copper (3.1%) Copper (10%) Silver (4.9%) Silver (15%) 1. Which two alloys contain large amounts of copper? ____________ and _____________. 2. Which metal is in both steel and stainless steel? _________________ 3. What are two alloys that contain aluminium? ___________ and _____________ 4. Which two metals are used to make both solder and type metal alloys? __________, _________ 5. What is the main metal in pewter? __________ 6. What percentage of copper is there in: a) b) Brass ____________ Bronze __________ 7. How much more copper is there in bronze than brass?_______________ 8. Which alloy has equal quantities of two metals? _______________ 9. Is sterling silver pure silver? (Yes or no) ____________ 27 10. From the information you've been given about gold alloys, how much gold would you think is in 14 carat gold? (99%, 80% or 58%) __________ Alloys are mixtures of metals and the amount of each metal in an alloy can be shown clearly by drawing a bar graph. The bar graph below shows the breakdown of the alloy brass, which contains 70% copper and 30% zinc. The whole bar has 10 sections, which means that each section represents 10%. Key: Copper (7 sections) Zinc (3 sections) Alloy Draw a bar graph for each of these alloys, using a different colour for each metal in the alloy. Include a key for each bar graph Solder Type metal Stainless steel Bronze Sterling silver Percentage (%) of each metal Lead (50%) Tin (50%) Lead (72%) Antimony (18%) Tin (10%) Iron (75%) Chromium (20%) Nickel (5%) Copper (92%) Tin (6%) Zinc (2%) Silver (92.5%) Copper (7.5%) Solder Key: Type Metal Key: Stainless Steel Key: Bronze Key: Sterling Silver Key: 28 CROSSWORD ACROSS CLUES 3 Will not dissolve 5 Process used in oil refineries 8 The change from liquid to gas 9 Mixture of two different liquids 12 Liquid made up of one substance dissolved in another 13 Solid which dissolves 14 Used to clean petrol in a car Down Clues 1 Used to separate the colours in ink 2 Two or more substances mingled together 4 Settles out on standing 6 Machine that separates mixtures by spinning 7 Sugar _____ in water 10 Used to separate iron from scrap metal 11 Liquid in which a substance dissolves 1 2 3 4 5 6 7 8 9 10 11 12 13 14 29 Find each of the following words. FILTRATE DILUTE RESIDUE EVAPORATE DISTILLATION SUSPENSION DISSOLVE SEDIMENT FUNNEL MAGNET SIEVE SOLVENT DECANT CONCENTRATED SOLUBILITY MIXTURE COLLOID CONDENSE SOLUTE INSOLUBLE SOLUTION U I M S D T O O N E A N G L T S T I M S O I N N U V D S A E U O E E E A S L U T S A I L D O C N E T T D G V U O N P S M I S O A O T S U E N L T M O T M S O N U C L D L L V E T E R I L S L D N O M N X E I N T O A L C O U E T L B I N T E D L T T L B L T N N L E T T M N E T L E A E V I S N O B S I F I L T R A T E E O E B I I D L X A G P U A I T E N I D D E U D I S E R T D O I M N E E S C M I I C S F O N N I S M A D S P L U E D O L T V X O U O A I L I S E F O E T T T L O S O T V V N E D U D U O U U S L P D I A E L F N N C S R B U T D E E I I E N N G N R E L I I O D N C U D N A T R E E E E U L E T S A E N D Y T I L I B U L O S N I N O D S E V E I S L I A T E I O T R S O I N D E T A R T N E C N O C D O N U C V E C S I L T O I T P L 30 Revision sheet 1. Substances that are not pure. M __________ 2. Choose which one is not a mixture: air, distilled water, soil. D _______ W__________ 3. There are at least this number of different particles in a mixture. T __________ 4. Air is made up of two gases. One of them is nitrogen, the other is? O __________ 5. Which gas makes up 4/5 (80%) of the air? N ________ 6. What are mixtures of metals called? A __________ 7. Solid particles can be separated from a liquid or gas by this method. F __________ 8. Which of these (oil filter, window gauze, vacuum cleaner, lemon squeezer) is not an example of filtration? L __________ S __________ 9. The salt left on your skin after a swim in the sea and a sunbake is an example of? C___________ 10. Evaporation involves the change from liquid to? G __________ 11. What common product is extracted by the evaporation of seawater? S __________ 12. This is a way of purifying water. D __________ 13. Distillation involves the change from liquid to gas and back to? L __________ 14. During distillation, what is the piece of equipment called that changes the gas (vapour) back to liquid? C __________ 15. This is how petroleum or crude oil can be separated into many different products. D________ 16. This is what petrol, diesel, heating oil and kerosene are distilled from. O_______ 17. The name for separation by spinning. C __________ 18. This method of separation is used in garbage dumps to sort the metals from the plastics and other materials. M ________ 19. Because sawdust floats and sand sinks, this method can be used to separate them. F_____________ 20. This can be used to separate two liquids that do not mix. S____________ C ______ 31