Unit A - Mix and Flow of Matter - Science in Action 8 PDF

UNIT A 2  In this unit, you will cover the following sections: 1.0 Fluids are used in technological devices and everyday materials. 1.1 WHMIS Symbols and Safety Procedures 1.2 The Many Uses of Fluids 2.0 The properties of mixtures and fluids can be explained by...

UNIT A 2  In this unit, you will cover the following sections: 1.0 Fluids are used in technological devices and everyday materials. 1.1 WHMIS Symbols and Safety Procedures 1.2 The Many Uses of Fluids 2.0 The properties of mixtures and fluids can be explained by the particle model of matter. 2.1 Pure Substances and Mixtures 2.2 Concentration and Solubility 2.3 Factors Affecting Solubility 2.4 The Particle Model of Matter and the Behaviour of Mixtures 3.0 The properties of gases and liquids can be explained by the particle model of matter. 3.1 Viscosity and the Effects of Temperature 3.2 Density of Fluids 3.3 Density, Temperature, and Buoyancy 3.4 Compression of Fluids 3.5 Pressure in Fluids—Pascal’s Law 4.0 Many technologies are based on the properties of fluids. 4.1 Technologies Based on Solubility 4.2 Technologies Based on Flow Rates and Moving Fluids 4.3 Designing a Working Model of a Fluid-Using Device 3 Exploring Canadian Invention Brings Water to African Villages AT THE utilized the pump to bring R ESE ARC HER S of Wat erlo o in clean drinking water to their University Ont ario hav e villages. southern Now, with the help of the developed a low-cost, shal -low International Development well pump that can easily be Research Centre in Ottawa, used in developing countries. Since the early 1980s, these inexpensive pumps are being made all over the many African and Southeast developing world. Asian communities have USING SCIENCE AND TECHNOLOGY TO SOLVE PROBLEMS In 1978, two Canadian scientists, Alan Plumtree and Alfred Rudin, invented a reliable hand-operated water pump suitable for use in developing countries. The new pump had to meet the following criteria: It had to be durable enough to work continuously for 18 hours a day. 4 Unit A: Mix and Flow of Matter  It had to be cheap enough for people in poorer countries to afford. It had to be simple enough for villagers to maintain and repair themselves. It had to be designed so that it could be manufactured within developing countries. This would create jobs and ensure that spare parts would be available. NEW TECHNOLOGY FROM OLD When the two scientists were researching pump designs, they noticed a pump at a Mennonite community in southern Ontario. It was practical and reliable and had been used for generations. With this pump as a model, they designed a hand pump with a tubing made out of a plastic called polyvinyl chloride (PVC). In the past, pumps were made of iron and steel, materials that are scarce and costly in many developing countries. PVC is inexpensive and available everywhere around the world. Plus, PVC doesn’t rust! The new PVC pump was light, sturdy, cheap to build, and easy to install and maintain. ADAPTING THE TECHNOLOGY Thanks to these Canadian inventors, villagers in developing countries are building and maintaining their own water pumps. Over 11 000 pumps are being used in 13 developing nations. Of course, the basic pump design can be modified for local conditions. For example, in Sri Lanka, they decided to use a leather washer instead of a plastic one. The advantage of the leather one is that it can be made locally. In Malawi, the spigot on the pump has to be made out of black metal because hyenas ate the original white plastic ones. The hyenas thought the white spigots looked like bones and kept chewing them off the pumps! Mennonites in southern Ontario have used hand pumps like this one for generations. Exploring 5  The PVC water pump is a good example of the importance of understanding a concept so that you can apply that understanding to different situations. In this case, the inventors knew about the properties of fluids and how a water pump operates. They applied this knowledge to develop a better pump that would work reliably for long hours and be easy to fix. In this unit, you will learn about the properties of fluids and see how they can be used to solve a variety of practical problems. These villagers in Thailand are being trained to maintain and repair a Canadian-invented hand pump. G i v e i t a TRY A C T I V I T Y THE NEW DRINK Now you have an opportunity to use what you already know about fluids and develop your problem-solving skills. You and your product development team have to find a solution to the following problem. Subject: DrinkIT Development From: "F. Izzy, President, GeeWHIZ Beverage Ltd." To: "Product Development Team, Fizz-A-Cola Division" We’re conducting research on a potential new drink, now code-named “DrinkIT.” Market research is underway, but we already know that our drink would sell if we could suspend a piece of floating fruit in it. So before we go any further in development, we need to know if a piece of fruit can float or be suspended in ANY liquid. Please determine which, if any, liquid would allow a fruit, such as a grape or blueberry, to float on it or be suspended in it. Test a variety of liquids to determine if a piece of fruit floats, sinks, or can be suspended in any of them. A variety of liquids will be available for you to test. You may use any one of these liquids or a combination of them. Design a procedure that will allow you to collect the necessary data. Have your teacher approve your design before you start. Prepare a reply to the president of the company that summarizes your results. 6 Unit A: Mix and Flow of Matter  Focus SCIENCE AND TECHNOLOGY On As you work through this unit, you will be reading about mixtures and fluids and doing activities that focus on science and technology. Science attempts to explain the phenomena in our world. The goal of technology is to provide solutions to practical problems. In this unit, one of your main tasks is to practise your problem- solving skills. The scientific knowledge you gain throughout this unit will help you develop these skills. Remember that many technological problems have many different solutions. There may be no one right way to solve the problem. These three steps can help you in your problem solving: clearly define your need develop appropriate plans and designs test and evaluate these designs You will be learning about the role of the properties of mixtures and fluids in both scientific research and technological developments. Use the following questions to guide your reading. 1. What are the properties of fluids? 2. Why are these properties and their interactions important? 3. What technologies have been designed to use the interactions between fluids and other materials? Exploring 7  1.0 Fluids are used in technological devices and everyday materials. Key Concepts In this section, you will learn about the following key concepts: WHMIS symbols properties of fluids Learning Outcomes When you have completed this section, you will be able to: explain WHMIS and other safety symbols describe safety precautions for using substances identify examples of fluids in products and devices describe examples of fluids used to transport, process, or use materials identify important properties of fluids The ladder on this truck helps firefighters save lives in tall buildings. But without fluids, firefighters wouldn’t be able to use it. It would take many people working together to put up a huge, heavy ladder like this one. But with the push of a button, a hydraulic system can raise and lower it easily. A hydraulic system uses fluids under pressure to move loads. It is just one of many technologies that use fluids to make our lives easier and safer. Fluids are substances that flow. Both liquids and gases are fluids. In this section, you’ll begin to learn about fluids and how and why they are used in technological devices and everyday materials. The first step in investigating fluids is learning how to work with them safely in the lab. 8 For Web links relating to 1.0, visit www.pearsoned.ca/scienceinaction 1.1 WHMIS Symbols and Safety Procedures Before you begin your study of mixtures and fluids, you need to review some safety rules and basic lab skills. Figure 1.1 shows a science class performing a science activity. Unfortunately, some of the students are not following proper safety procedures. Work with a partner to identify and list the problem actions. Then suggest a better, safer way to perform each action. After you have finished, share your observations with the class. Figure 1.1 What are these students doing wrong? What are they doing right? WHMIS AND OTHER HAZARD SYMBOLS You will be doing many activities in this unit. Before you do an activity, read through it and watch for “Caution!” notes that will tell you if you need to take extra care. There are two areas of special consideration when working in the lab—understanding warning labels and following safety procedures. Some of the materials you will use in the lab are hazardous. Always pay attention to the warning labels described on the next page, and follow your teacher’s instructions for storing and disposing of these materials. If you are using cleaning fluids, paint, or other hazardous materials at home, look on the labels for special storage and disposal advice. Fluids Are Used in Technological Devices and Everyday Materials 9 info BIT All hazardous materials have a label showing a hazard symbol. The hazard symbol has a safety warning and a shape to indicate Symbol Shapes how hazardous the material is. You may have already seen these labels on fluids you find at home, such as bleach or oven cleaner. There are two separate pieces of information for each symbol. The first is the shape of the symbol, shown in the infoBIT. A yellow triangle means “caution,” an orange diamond means “warning,” and a red octagon means “danger.” caution The second piece of information is a picture inside the shape that indicates the type of hazard. There are seven pictures of common hazards shown in Figure 1.2. warning flammable toxic hazard explosive hazard hazard danger These shapes and their colours indicate how irritant hazard corrosive hazard biological hazard electrical hazard dangerous the substances are. Figure 1.2 These pictures tell you what type of hazard to watch out for. Figure 1.3 shows some of the WHMIS symbols. WHMIS stands for Workplace Hazardous Materials Information System. This is another system of easy-to-see special symbols on hazardous materials. These symbols were designed to help protect people who use potentially harmful materials at work. compressed gas dangerously reactive oxidizing poisonous and infectious material material causing immediate and serious toxic effects flammable and biohazardous corrosive poisonous and infectious combustible material infectious material material causing other toxic effects Figure 1.3 WHMIS symbols 10 Unit A: Mix and Flow of Matter UNDERSTANDING THE RULES re SEARCH When performing a science investigation, it is very important that WHMIS Symbols at you follow the lab safety rules. School Check around your Lab Safety Rules school for WHMIS symbols. Try the art room or a cleaning 1. Read all written instructions before doing an activity. room. Make a map 2. Listen to all instructions and follow them carefully. showing where the 3. Wash your hands carefully after each activity and after different hazardous handling chemicals. materials are located in your school. 4. Wear safety goggles, gloves, or an apron as required. 5. Think before you touch. Equipment may be hot and substances may be dangerous. 6. Smell a substance by fanning the smell toward you with your hand. Do not put your nose close to the substance. 7. Do not taste anything in the lab. 8. Tie back loose hair and roll up loose sleeves. 9. Never pour liquids into containers held in your hand. Place a test tube in a rack before pouring substances in it. 10. Clean up any spilled substances immediately as instructed by your teacher. 11. Never look into test tubes or containers from the top. Always look through the sides. 12. Never use cracked or broken glassware. Make sure you follow your teacher’s instructions when getting rid of any broken glass. 13. Label any container you put chemicals in. 14. Report all accidents and spills immediately to your teacher. 15. If there are WHMIS (Workplace Hazardous Materials Information System) safety symbols on any chemical you will be using, make sure that you understand all the symbols. See Toolbox 1 at the back of this book. Fluids Are Used in Technological Devices and Everyday Materials 11  SAFETY BEGINS WITH YOU Not following one or more of the lab safety rules could result in injury to you or your classmates. Follow the list of 15 safety rules to ensure that you work in a safe manner. Your teacher will also discuss any specific rules that apply to your classroom. After you have read the rules here, you can read more about safety in Toolbox 1 at the end of the book. Remember that safety in a science class begins with you. Before you start any activity, you should be prepared to follow the safety instructions outlined by your teacher and this text keep an eye open for possible hazards, and report them immediately show respect and concern for your own safety and the safety of your classmates and teachers CHECK AND REFLECT 1. What does each hazard warning label mean on the fluids shown in Figure 1.4? Figure 1.4 Warning labels on hazardous products 2. Choose five of the lab safety rules given on page 11. For each one, explain briefly why it’s important to follow it. Give an example of what could happen to a student who didn’t follow that rule. 3. Make your own chart of hazard warning symbols. When you go home, check for each symbol on materials where you live or at your local grocery store. List two or three substances or items to which the symbol applies. 12 Unit A: Mix and Flow of Matter  info BIT 1.2 The Many Uses of Fluids Agrifoam Cold Crop A fluid is anything that has no fixed shape and can flow. Usually it Protector is a liquid or a gas. Look at Figure 1.5. How many different Frost damage is a big examples of fluids being used can you observe? Make a list of the risk for farmers who fluids you see there and how they are being used. Include one grow fruit. To help additional use for each fluid. Remember to note uses by other living farmers protect their things besides humans. After you have made your list, group the crops, Canadians examples into four different categories. Label each category with a Dr. D. Siminovitch and title that makes sense to you. J.W. Butler invented Agrifoam Cold Crop Protector. Agrifoam is a shaving-cream-like material that can be sprayed onto plants to protect them from freezing. Figure 1.5 How are fluids being used? FLUIDS MAKE IT EASIER TO USE MATERIALS It’s easy to think of many fluids you use every day, such as water, soft drinks, and detergents. One of the reasons that fluids are so useful is that they make it easier to transport, process, and use different kinds of materials, even if these materials are solids. Fluids Are Used in Technological Devices and Everyday Materials 13  Slurries Think about washing off a sidewalk or driveway with a hose. If you had a coating of mud or sand on your driveway, you could turn your hose on it. The water would wash or carry the mud or sand off the driveway. This mixture of water and solids is called a slurry. Slurry technology—the transport of solids in water—is important in many applications. One of these is in mining oil sands. Syncrude in Alberta is the world’s largest producer of oil from oil sands. Syncrude started out by using conveyor belts to move the oil sands from the mine to the processing plant. But this technology proved to be very expensive. Now Syncrude creates an oil-sand slurry at the mine site and pumps this slurry through pipelines to the processing plant. Figure 1.6 Because it’s a Fluids Become Solids fluid, the water can carry Fluids are easy to move, and they take the shape of containers. the sand and other solids Because of these properties, many of the things we see and use as away. solids were originally prepared as fluids. Glass, for example, is manufactured by heating a mixture of substances that includes sand, limestone, and other carbonates. Other materials can be added to give the glass colour or special qualities. The mixture is heated in a furnace at 1000°C until it becomes a fluid. This allows it to be shaped into the form needed for particular uses, such as bottles, windows, or fibre-optic strands. Figure 1.7 Glass bottles being formed 14 Unit A: Mix and Flow of Matter  Steel is another example of the use of fluids as a stage in processing materials. Steel consists of a mixture of iron, carbon, and small quantities of other substances. This mixture is heated to 1650°C to melt everything together, and to add more materials. The fluid steel is then shaped into the desired forms and allowed to cool. Fluids Can Hold Other Materials The ability of fluids to spread or flow and to carry other materials makes them useful in many applications. Toothpaste is an example that you may not have thought of. Most toothpaste contains powdered materials, such as bauxite, to polish your teeth. It also contains a detergent to clean your teeth, and fluoride to keep your teeth strong. Substances called binders, made from wood pulp, keep the paste mixed. Colouring and flavouring are added to make the mixture more agreeable. USEFUL PROPERTIES OF FLUIDS From the information you have learned so far in this section, you re SEARCH can begin to appreciate the importance of fluids in our world. Froth Flotation You’ve seen some examples of the different ways that fluids are A common method of involved in transporting, processing, and using materials. Fluids processing mineral can be used in all these ways because of their properties. ore is called froth By understanding the properties of fluids, people can design flotation. How are technological devices that use these properties. Later in this unit, fluids used in this you will be exploring these properties: viscosity, density, buoyancy, process? and compressibility. Figures 1.8 to 1.12 on the next page show how these properties can be important in choosing and using fluids in different applications. G i v e i t a TRY A C T I V I T Y ANOTHER PROPERTY OF FLUIDS In this activity, you will observe a situation that uses two liquids—detergent and water. You have a pan of water with some pepper floating on it. Add a couple of drops of liquid detergent. What happens? Suggest a situation where what you observed could be used in a practical way. Present your ideas to the class either orally or as a short written description. Fluids Are Used in Technological Devices and Everyday Materials 15  Figure 1.8 Your bicycle starts to make grinding noises as you pedal. What do you do? You use oil on your bicycle or in a car to make sure that the parts operate smoothly together. The viscosity of the oil that you use is important. Viscosity describes how easily a fluid flows. You will learn more about viscosity in section 3.0. Figure 1.9 In making maple syrup, you have to determine when the mixture reaches the right concentration of sugar. A device called a hydrometer is used to measure the density of the syrup to find out if there is enough sugar in it. You will learn more about density in section 3.0. Figure 1.10 This ship floats because of the buoyant force of the water acting on it. You will Figure 1.12 The hovercraft operates by directing learn more about buoyancy in air downward so it floats on a fluid cushion over section 3.0. the waves. Figure 1.11 This jackhammer is pneumatic. Systems that use compressed air are called pneumatic systems. Hydraulic systems use liquids to lift or move things. You will learn more about pneumatic and hydraulic systems when you learn about the compression of fluids in sections 3.0 and 4.0. CHECK AND REFLECT 1. Review the list of fluids and their uses that you made at the beginning of this subsection when you looked at Figure 1.5. Are there any changes you would make based on what you have learned? Add at least three other examples, and make one new category for your list. 2. Describe an example where materials are prepared as fluids so they can be moved more easily. 3. Explain why it is important for steel to go through a fluid phase as it is being produced. 16 Unit A: Mix and Flow of Matter  SECTION REVIEW Assess Your Learning 1. What labels would you expect to find on containers of the following materials? a) oven cleaner in a spray can b) bleach c) paint thinner d) unknown bacteria 2. Describe the process for getting rid of broken glass in your class. 3. What protective measures must you take when you work around an open flame? 4. Describe an example where materials are prepared as fluids to make it easier to use them. 5. Describe two technologies that require a specific property of a fluid to function properly. Focus SCIENCE AND TECHNOLOGY On The goal of technology is to provide solutions to practical problems. For example, toothpaste is a technology to solve the problem of tooth decay. It was invented to keep teeth clean and strong. It also freshens your breath. Think back to what you learned in this section. 1. What were some practical problems that you read about? 2. What technologies were used to solve these problems? 3. Did it seem to you there would be more than one way to solve some of these problems? Fluids Are Used in Technological Devices and Everyday Materials 17  The properties of mixtures and fluids 2.0 can be explained by the particle model of matter. Key Concepts In this section, you will learn about the following key concepts: pure substances, mixtures, and solutions solute and solvent concentration solubility and saturation points particle model of matter Learning Outcomes When you have completed this section, you will be able to: distinguish between pure substances and mixtures define concentration and solubility identify factors that affect solubility and rate of dissolving relate the behaviour of mixtures to the particle model of matter All the objects in the pictures on this page have at least one thing in common. They are all examples of matter. Matter may be hard, soft, rough, smooth, round, square, hot, or cold. It may be smaller than a cell or larger than the sun. Matter may have colour or it may be colourless. Matter is what makes up everything in our universe. Matter can be organized in different ways. You already know one way: matter can be classified as solid, liquid, or gas. In this section, you will look at another classification system. This system classifies matter as pure substances or mixtures. You will also learn about a model that you can use to describe the nature of matter. This model will help you understand fluids and their properties. 18 For Web links relating to 2.0, visit www.pearsoned.ca/scienceinaction 2.1 Pure Substances and Mixtures All matter is either a pure substance or a mixture. A pure substance, such as sugar, is made up of only one kind of matter. A mixture, such as soil, is made up of a combination of different substances. G i v e i t a TRY A C T I V I T Y CLASSIFYING PURE SUBSTANCES AND MIXTURES You can find examples of pure substances and mixtures all around you. Work with a partner to make a list of 20 different things you have used in the last day or two. Try to include at least two solids, two liquids, and two gases. Classify the items in your list as either pure substances or mixtures. If you are not sure into which grouping an item fits, make a third grouping. Review your groupings and answer the following questions in your notebook or in a class discussion: Could you tell pure substances and mixtures apart? Which were the hardest items to classify? Did some items seem to be neither a pure substance nor a mixture? PURE SUBSTANCES A pure substance is made up of one type of matter Pure Substances and has a unique set of characteristics or properties. For example, aluminum foil, baking soda, and Matter distilled water are all pure substances. You cannot separate them into different substances. Mixtures MIXTURES Mixtures are two or more substances combined together. In a mixture, each substance keeps its properties, but it may be difficult to identify these properties. For example, you may not see the sugar in a drink of soda pop, but you can certainly taste it. Sometimes it is easy to identify the different substances in the mixtures. For example, you can see the different vegetables in a package of mixed vegetables. The Properties of Mixtures and Fluids Can Be Explained by the Particle Model of Matter 19 info BIT MECHANICAL MIXTURES AND SOLUTIONS If you think about pure substances, you might list common What Are Pennies examples such as sugar, water, salt, and oxygen gas. Some other Made Of? examples you might think of may seem to be pure substances, but Until 1997, pennies aren’t. For example, how would you classify vinegar—is it a pure were made of a pure substance or a mixture? To be able to classify matter, you need to substance—copper. Since then, other know more about mixtures. substances have been In a mechanical mixture, you can see the different substances added so pennies are that make up the mixture. Soil and mixed vegetables are both now a mixture of mechanical mixtures. This type of mixture is sometimes called a metals. Mixtures of heterogeneous mixture. In other mixtures, you can’t see the metals are called different substances that make them up. These mixtures may be alloys. solutions, suspensions, or colloids. A solution looks as if it is all one substance. It is called a homogeneous mixture. Sometimes it is difficult to tell the difference between a pure substance and a solution without performing some tests. You can learn more about suspensions and colloids on the next page. The chart in Figure 2.1 summarizes the classification of matter as pure substance, mechanical mixture, solution, suspension, or colloid. Figure 2.1 Matter classification chart 20 Unit A: Mix and Flow of Matter SUSPENSIONS AND COLLOIDS A suspension is a cloudy mixture in which droplets or tiny pieces of one substance are held within another substance. If you leave a suspension undisturbed, its parts will usually separate out. Muddy water is an example of a suspension. A colloid is also a cloudy mixture but the droplets or tiny pieces are so small that they do not separate out easily. Homogenized milk is a colloid of tiny cream droplets in whey. PURE SUBSTANCE OR SOLUTION? Figure 2.2 A foam is a Look at the list of different fluids in this table. Answer the colloid of a gas in a liquid. The foam in this following questions. photo is used for Are these fluids pure substances or solutions? insulation. It comes out How would you determine if your classification is correct? of the can as a fluid, and then hardens in place to Copy the table into your notebook. In your table, mark ✔ in the seal cracks. column to which each fluid belongs. Fluid Pure Substance Solution soda pop hot chocolate water apple juice windshield washer fluid PAPER CHROMATOGRAPHY For some fluids, the paper chromatography test can be used to determine if they are pure substances or solutions. A piece of filter paper is placed partly in a solution. If the fluid is a pure substance, it will move up a strip of filter paper to one level. If the fluid is a solution, the different substances in it will move up the paper to different levels. This is a powerful technique for separating several substances mixed together. The Properties of Mixtures and Fluids Can Be Explained by the Particle Model of Matter 21 Inquiry P A P E R C H R O M AT O G R A P H Y Activity The Question Is the black ink in a marker pen a pure substance or a solution? The Hypothesis Materials & Equipment Write a hypothesis stating whether the marker pen’s ink is a pure substance filter paper or coffee filters or a solution. (See Toolbox 2 if you need help with this.) pencil 250-mL beaker Procedure black, water-soluble marker 1 Cut a piece of filter paper so that it is slightly larger than the width and height pen of the beaker. This will become your chromatogram. paper towels 2 Using a pencil, draw a horizontal line 1 cm from one end of the paper. water 3 Put 2 large dots of black ink on the filter paper along the horizontal line. Make sure that the dots aren’t too close to each other. 4 Pour water into the beaker to a depth of 0.5 cm. 5 Predict what will happen to the ink dots when you put the paper in the water. 6 Curve the paper so that it can stand up by itself in the beaker. Be sure the bottom edge is touching the bottom of the beaker. The line of dots should be just above the water. Do NOT allow the water to touch the line of dots. 7 The water will move up as it soaks into the paper. When the water almost reaches the top of the paper, take the paper out and place it on a paper towel. Allow it to dry. Collecting Data Figure 2.3 Step 1. Cut a piece of filter paper slightly larger 8 Record your observations. Be sure to include or draw your strip of paper. than the width and height of the beaker. Analyzing and Interpreting 9 What happened to the original colour of the black dots? Forming Conclusions 10 Is the ink in a marker a pure substance or a solution? Support your answer with your data. Applying and Connecting Chromatography has many uses, including identifying forged cheques. In one recent case, a greedy man changed the dollar amount on a will from $1000 to $10 000 simply by adding an extra 0. Using chromatography and comparing the ink from the different digits, investigators determined that the ink from one of the zeros came from a different pen. The man was convicted of forgery. Figure 2.4 Step 6. Curve the Extending paper so it will stand up by itself in the beaker. What would happen if you tested coloured markers? Try it and find out. 22 Unit A: Mix and Flow of Matter  Figure 2.5 You can see from this chromatogram that the ink is not a pure substance. How many substances are mixed together in this kind of ink? READING CHROMATOGRAMS re SEARCH The filter paper used to test the substance is called a chromatogram. Figure 2.5 shows a filter paper with two spots of Separating Mixtures ink from a black marker on it after it was placed in water. The Methods of water soaked into the paper and eventually dissolved the ink spots. separating mixtures Notice how the different substances making up the ink separated at can be classified as different levels on the chromatogram. The distance a substance either destructive or moves depends on its attraction to the paper. Some substances are non-destructive. Use more strongly attracted to the paper. Those with the strongest print or electronic attraction to the paper don’t move very far. Those with the weakest resources to find attraction move farthest. examples of methods and what they are used for. Try to find examples other than CHECK AND REFLECT chromatography. 1. What is the difference between a mixture and a pure substance? 2. Below is a list of some examples of matter. Classify each example as a heterogeneous mixture, a homogeneous mixture, or a pure substance. Explain your classification in each case. a) chocolate chip cookies b) coffee with cream c) aluminum foil d) potting soil e) gold medal 3. Create a flowchart that would help you classify matter into heterogeneous mixtures, homogeneous mixtures, or pure substances. Hint: Review the flowchart on page 20. Test your flowchart using the examples in question 2. 4. What practical uses can you think of for chromatography? The Properties of Mixtures and Fluids Can Be Explained by the Particle Model of Matter 23  2.2 Concentration and Solubility Dissolving one substance into another makes a solution. The substance that dissolves is called the solute. The substance that does the dissolving is called the solvent. In a concentrated solution, there are large amounts of solute in the solvent. For example, you may have made orange juice from frozen juice concentrate. The concentrate has a large amount of orange solids (solute) in a small amount of water (solvent). You add water to make a diluted solution. A diluted solution has small amounts of solute in the solvent. So the orange juice you drink is actually a diluted solution. MEASURING CONCENTRATION info BIT Concentrated and diluted are not exact terms. They don’t tell you the actual amount of solute in the solvent. The concentration of a solution tells you the amount of solute dissolved in a specific The Smell of Chlorine A concentration of one amount of solvent. For example, a solution with 50 g of solute part per million of dissolved in 100 mL of water has a concentration of 50 g/100 mL of chlorine in a swimming water. This is read as “fifty grams per one hundred millilitres.” pool can be detected Another common way of describing concentration is to state the by the human nose. number of grams of solute per 100 mL of solution. A concentration of 50 g/100 mL of solution means that 100 mL of the solution has 50 g of solute dissolved in it. Sometimes you will see concentrations stated in other ways. For example, the label on a juice box may say “5% real juice.” Very low concentrations may be stated in parts per million (ppm). G i v e i t a TRY A C T I V I T Y COMPARING SOLUTIONS You have three drinks in front of you. You know how they were made, but are unsure which one has the highest concentration of juice crystals. The first drink has 10 g of juice crystals dissolved in 50 mL of water. The second drink has 15 g of juice crystals dissolved in 100 mL of water. The third drink has 6 g of juice crystals dissolved in 25 mL of water. Work with a partner to make a plan to figure out the concentration of each drink. What was the most concentrated drink? How did you determine this since all three drinks had different amounts of solvent? 24 Unit A: Mix and Flow of Matter COMPARING CONCENTRATIONS To compare the concentrations of two solutions, you need to know math Link the amount of solute in the same volume of solvent for each A cleaning solution is solution. For example, you have two solutions. One has 10 g of salt made of 5.25 g of a in 50 mL of water (10 g/50 mL). The other has 25 g in 100 mL chemical called (25 g/100 mL). Which one is more concentrated? sodium hypochlorite For a comparison, the volume of solvent must be the same for in 100 mL of water. If both solutions. In our example, this means doubling the 10 g/50 mL you had a solution of to 20 g/100 mL. So now you are comparing the amount of salt per 21 g of sodium 100 mL of water in both solutions. The solution with the most hypochlorite in 100 mL solute in the same amount of water is the most concentrated: the of water, how would solution with 25 g/100 mL is more concentrated than the one with you make the cleaning 20 g/100 mL. solution? SATURATED AND UNSATURATED SOLUTIONS You have just learned how to state the concentration of a solute in a solvent. You know that you can make a very diluted solution by adding a small amount of juice crystals to water. If you add more juice crystals, the solution becomes more concentrated. As long as the juice crystals keep dissolving, you have an unsaturated solution. An unsaturated solution is one in which more solute can dissolve. What would happen if you kept adding juice crystals until no more would dissolve? You would now have a saturated solution. A saturated solution is a solution in which no more solute can dissolve at a given temperature. Solubility is the maximum amount of solute you can add to a fixed volume of solvent at a given temperature. In our example, the solubility of the juice crystals would be the maximum amount of juice crystals that you could dissolve in water at that temperature. Every solution has a saturation point at a given temperature. This occurs when no more solute can be dissolved in a fixed volume of solvent at that temperature. Figure 2.6 When you drink juice made from concentrate, you have mixed water with the concentrate to make a diluted solution. The water is the solvent and the part of the concentrate that dissolves is the solute. The Properties of Mixtures and Fluids Can Be Explained by the Particle Model of Matter 25 Inquiry S AT U R AT E D AND U N S AT U R AT E D S O L U T I O N S Activity The Question How can you make saturated solutions? Materials & Equipment graduated cylinder beaker balance paper to hold solutes spoon or scoopula water at room temperature powdered drink crystals sugar salt stir sticks Figure 2.7 Step 2. Accurately measure 5 g of a substance. Procedure 1 Use the graduated cylinder to measure 50 mL of water into a beaker. 2 Measure 5 g of one substance. Add this to the water. 3 Stir the mixture until the substance has dissolved. Record your observations in the table. 4 Keep adding more of the same substance to the water, 5 g at a time, until no more will dissolve. 5 Repeat steps 1 to 4 for each substance. 26 Unit A: Mix and Flow of Matter Collecting Data 6 Make a table like the one below in your notebook: Substance Mass Added Volume of Concentration Observations Water in g/100 mL Water 7 Fill in the table for each substance you use. Analyzing and Interpreting 8 Calculate the concentration of each solution in grams per 100 mL. Don’t forget you used only 50 mL of water, so you will need to correct the differences in mass and volume. 9 How did you know when a solution was saturated? Forming Conclusions 10 Describe how you made saturated solutions and calculated the concentration of each of your solutes. Applying and Connecting Many industrial processes depend on producing solutions of various concentrations. In some situations, the more concentrated the solution, the more useful the solution can be. An example of this is red dye for food colouring. In the 1970s, synthetic red dye was banned because of its potential carcinogenic effects. Industry needed a safe replacement. Scientists found it in an insect called the cochineal [kotch-e-neel] that lives in cacti in the Andes Mountains of South America. This bright red natural dye has been approved for use in cosmetics, drugs, and foods. Recently, two chemists from Simon Fraser University, Dr. Cam Oehlschlager and Dr. Eva Czyzewska, developed a method of improving the production process to make a more concentrated dye. The process is being used on the condition that the dye production remain close to the source of the insects. This is important because rural people are employed in collecting the insect. Figure 2.8 Cochineal insects live on cacti. They are the source for a bright red dye. The Properties of Mixtures and Fluids Can Be Explained by the Particle Model of Matter 27 re SEARCH COMPARING SOLUBILITY OF COMMON SUBSTANCES The solubility of a solute is the maximum amount of that solute Insoluble Substances that you can dissolve in a given amount of solvent at a given Sometimes a temperature. If you did the last Inquiry Activity, you noticed that substance won’t dissolve in a solvent. different solutes have different solubilities. Solubility is a unique That substance is property for each substance. The table below shows the solubilities insoluble in that of some common substances in water at 0°C. You can see that 35.7 g solvent. Find out why of salt will dissolve in 100 mL of water at 0°C, and 180 g of sugar some substances are will dissolve in 100 mL of water at 0°C. insoluble. Solubility in g/100 mL of Water at 0°C Compound Solubility (g) salt 35.7 baking soda 6.9 carbon dioxide 0.35 sugar 180 hydrogen 0.00019 oxygen 0.007 ammonia 92 CHECK AND REFLECT 1. What is the difference between a diluted solution and a concentrated solution? 2. If a solution has a concentration of 75 g per 100 mL, what does this mean? 3. Calculate the concentrations in grams per 100 mL for the following solutions: a) 10 g of chocolate in 50 mL of water b) 3 g of sugar in 300 mL of water c) 5 g of maple syrup in 25 mL of water 4. What is the difference between a saturated solution and an unsaturated solution? 5. What is the solute in a fruit punch drink? 28 Unit A: Mix and Flow of Matter 2.3 Factors Affecting Solubility In the last section, you learned about solubility. It is the maximum amount of solute you can dissolve in a given amount of solvent at a given temperature. Solubility depends on at least three factors: the type of solute, the type of solvent, and the temperature. First, let’s consider the type of solute and the type of solvent. G i v e i t a TRY A C T I V I T Y D I S S O LV I N G S O L U T E S IN D I F F E R E N T S O LV E N T S Your teacher will give you these solutes: juice drink crystals, petroleum jelly, sugar, and salt. You will have two solvents: water and vegetable oil. Which solutes will dissolve in water and which solutes will dissolve in vegetable oil? Create a procedure that will allow you to collect data that will answer the above question. You will have to design a fair test to determine the answer to this question. (See Toolbox 2 for more information on how to design a fair test.) TYPES OF SOLUTES AND SOLVENTS The most common solvent is water. Water is sometimes referred to as the universal solvent because it can dissolve so many different substances. If you see the term aqueous solution, that means the solvent is water. (Aqua is the Latin word for water.) It is important to remember that solutions do not have to be made up of only liquids. The table below contains examples of solutes and solvents in other states. Examples of Common Solutions Solute Solvent Solution gas gas air (oxygen and other gases in nitrogen) gas liquid soda water (carbon dioxide in water) liquid liquid antifreeze (ethylene glycol in water) liquid solid rubber cement (benzene in rubber) solid liquid seawater (salt and other substances in water) solid solid brass (zinc and copper) The Properties of Mixtures and Fluids Can Be Explained by the Particle Model of Matter 29 Inquiry T E M P E R AT U R E AND SOLUBILITY Activity The Question What effect does temperature have on the solubility of a substance? Hint: Recall that solubility is the maximum amount of solute (solid) that you can dissolve in a fixed volume of solvent (liquid) at a given temperature. Materials & Equipment 2 beakers The Hypothesis water Write a hypothesis about how the temperature of the solvent affects the amount thermometer of solute that can dissolve in it. hot plate or access to hot water Procedure solute and solvent 1 Decide which materials you will need to test spoon or scoopula the hypothesis. Caution! graduated cylinder 2 Plan your investigation. If you spill liquid on triple beam or electronic your hands, wash it a) What variable(s) will change? balance off with water right b) What variable(s) will stay the same? away. Wash your 3 Write a procedure and show it to your teacher. hands when you have Do not proceed any further until it is approved. completed the activity. 4 Carry out your investigation. Collecting Data 5 Make sure you have recorded at least the following information: the hypothesis, your Caution! procedure, the temperature of the liquids used, Always heat solvents and the mass of solute added. in a water bath. Analyzing and Interpreting 6 Share and compare your results with your classmates. What variables did each group have to keep the same so that you could compare results? Forming Conclusions 7 In a short paragraph, describe your results and how they compared with the hypothesis. Figure 2.9 Carefully measure the mass of solute that you use. Extending A supersaturated solution is one that contains more solute than it normally would be able to dissolve at a certain temperature. How do you think you could make a supersaturated solution with the solute and solvent combination you tested here? Find out how to do this and try it. 30 Unit A: Mix and Flow of Matter SOLUBILITY CHANGES WITH TEMPERATURE info BIT For most common solid or liquid substances, solubility increases as The Colour of Money the temperature of the solvent increases. For example, at 25°C, you In 1857, Thomas Sterry can dissolve 36.2 g of salt in 100 mL of water, but at 100°C, you can Hunt, a professor at dissolve 39.2 g. The reverse is true for a gas. As the temperature McGill University in increases, the solubility of a gas in a liquid solvent decreases. Montreal, produced a green ink called Thermal Pollution chromium trioxide. This decrease in the solubility of gases can have a serious effect on This green ink is used the environment. Many industrial plants use water as a coolant in to this day to print their processes. Usually this water is drawn from a lake or a river. American money. Once the water is used, it is warmer than when it was taken into Dr. Hunt’s green ink the plant. Before it can be returned to the lake or river, it must be cannot be dissolved stored in a cooling pond. What would happen if the warm water or copied by were poured directly back into the river or lake? This is commonly photography. called thermal pollution. All water contains various amounts of different gases, including oxygen. The oxygen is important for supporting life that lives in the water. If the temperature of the water increases, the concentration of oxygen decreases. This occurs because the solubility of a gas in a liquid solvent decreases as the temperature increases. So the solubility of the oxygen is less in the warmer water. What do you think will happen to the living organisms in the lake or river if the amount of oxygen in the water decreases greatly? CHECK AND REFLECT 1. Why is water called “the universal solvent”? 2. What factors affect the solubility of a solute? 3. For the substances in the chart below, answer the following questions. Solubility in g/100 mL of Water Substance at 0°C at 100°C sodium chloride 35 39 sodium nitrate 74 182 sodium carbonate decahydrate 21 421 a) Which substance is the most soluble at 100°C? b) Which substance is the most soluble at 0°C? c) Which substance shows the most change in solubility as the temperature increases? The Properties of Mixtures and Fluids Can Be Explained by the Particle Model of Matter 31  2.4 The Particle Model of Matter and the Behaviour of Mixtures As you study the properties of mixtures, you may observe events that seem difficult to explain. For example, how would you explain the following situations involving mixtures? Situation 1. Can something dissolve without stirring? Figure 2.10a) shows a petri dish three-quarters full of water. A crystal of potassium permanganate was carefully added to the still water. The dish was left for 5 min without disturbing it. Figure 2.10b) shows the potassium permanganate after 5 min. What happened to it? Why do you think this happened? Figure 2.10a) The potassium Figure 2.10b) What happened to the permanganate has just been added to potassium permanganate after 5 min the water. in the water? Situation 2. Can you combine two liquids and have a volume less than the sum of the volumes when you started? A lab technician carefully measured 20 mL of rubbing alcohol into one graduated cylinder and 20 mL of water into another. He then combined the two liquids. The combined liquid filled the graduated cylinder to a level of 39 mL. Did the technician make a mistake? Figure 2.11a) 20 mL of rubbing alcohol Figure 2.11b) The two liquids combined in a 50-mL cylinder Can you explain why this and 20 mL of water in separate 25-mL cylinders measurement resulted? 32 Unit A: Mix and Flow of Matter  You may have developed explanations for these two situations, but you may not be completely sure of your answers. A model of info BIT matter would help explain these and other observations. How Big Is a Particle? There are about 1018 THE PARTICLE MODEL OF MATTER particles in a Why did the potassium permanganate start to dissolve without snowflake. That’s the being stirred? Why did the volumes not add up when the water and number 10 with 18 the rubbing alcohol were added together? The particle model of zeros after it. matter can help to explain these and other situations. The particle model has four main points that describe the structure of matter. Using this model, you will be better able to explain the properties of mechanical mixtures and solutions. As you look through the description of the particle model shown here, think about the situations described on the previous page. 1 All matter is made up of tiny particles. Different substances are made up of different particles. This means every object in any state is made up of tiny particles too small to see. There are more particles in a given volume of solid than there are in the same volume of a liquid or a gas. 2 The tiny particles of matter are always moving and vibrating. For solids, this movement is like wiggling in one place. For liquids, the particles are sliding around and over each other. For gases, this movement means moving as far as the space they are in allows. 3 The particles in matter may be attracted to each other or bonded together. Some particles, such as water, have more attraction for other particles, such as salt, than for each other. 4 The particles have spaces between them. Notice the difference in the amount of space between particles of a solid and a gas. The Properties of Mixtures and Fluids Can Be Explained by the Particle Model of Matter 33  G i v e i t a TRY A C T I V I T Y USING THE PARTICLE MODEL OF MATTER You have 50 mL of sand in one container and 250 mL of marbles in another container. When you mix the contents of the two containers, you will be modelling what happens when alcohol and water are mixed together. What will be the total volume of the sand and marbles when they are mixed together? Slowly pour the 50 mL of sand into the container of marbles. Record your observations. Use the particle model to explain what happened when you mixed the sand and marbles together. Now use it to explain what happened when the technician mixed the alcohol and water earlier in this subsection. HOW THE PARTICLE MODEL EXPLAINS MIXING SUBSTANCES The alcohol and water that the technician mixed together earlier are two different substances. They are made of different particles, and these particles are different sizes. When the two substances are mixed together, the smaller particles of one substance fill in the spaces between the larger particles of the other. Figure 2.12 shows a model of this situation. The particle model can also explain why substances dissolve. The particle model states that particles are attracted to each other. However, particles in some substances are more attracted to particles in other substances than to each other. For example, Figure 2.12 The marbles consider the situation in Figure 2.10 at the beginning of this and sand represent two different substances made subsection. When potassium permanganate is placed in water, its up of particles of two particles are attracted to the water particles. This is the process different sizes. Notice how called dissolving. In a solution, the particles of the solute the sand fills in the spaces (potassium permanganate) are attracted to the particles of the between the marbles. solvent (water). The solute dissolves in the solvent. This is why a solute seems to disappear when mixed with a solvent. FACTORS AFFECTING THE RATE OF DISSOLVING In the subsection 2.3, you investigated different factors that affected the solubility of a substance. You found out that the kind of solute, the kind of solvent, and the temperature all had roles in solubility. 34 Unit A: Mix and Flow of Matter Another important consideration in dissolving solutes is the rate of re SEARCH dissolving. How fast will a solute dissolve in a solvent? How can you make a solute dissolve more quickly? Look at Figures 2.13a)–c). Atomic Structure They show how the particle model can explain the factors that The particle model is affect the rate at which a solute dissolves. a simple way of describing matter and its behaviour. Atomic structure is another way. You have probably heard about atoms. How are atoms related to particles? Find out about atomic structure. Figure 2.13a) Temperature. Increasing the temperature makes the particles move faster. Heat energy is transferred by the movement of the particles. Because the solvent particles are moving faster, they bump into the solute particles faster. Figure 2.13b) Size of Pieces. Small pieces of solute dissolve more quickly than large pieces. All the smaller pieces together have more surface area among them for the solvent particles to bump into. Think of cooking a potato in water. If you put the whole potato in, it takes a long time to cook. If you cut the potato up into smaller pieces, the cooking time becomes much shorter. Figure 2.13c) Stirring. Stirring moves all the particles around, so the solvent particles bump into the solute particles. The Properties of Mixtures and Fluids Can Be Explained by the Particle Model of Matter 35  CHECK AND REFLECT 1. Make a particle sketch showing how instant coffee dissolves in hot water. 2. You’ve been asked to try out a new type of fruit drink flavouring that comes in the form of a cube that dissolves in water. You’re in a hurry to try it so you want to dissolve it as quickly as possible. Name three ways of speeding up dissolving. Explain each one using the particle model. 3. Figure 2.14 shows a Web page about the particle model that is still under construction. The text hasn’t been added yet. a) In your notebook, complete the Web page with information that explains the picture. Include one hyperlink topic in the text of your Web page. b) Write one other Web page that explains your hyperlink. The text on this page should use the words solubility and factors affecting the rate of dissolving. Figure 2.14 Question 3. Web page under construction 4. Why did the potassium permanganate crystals start to dissolve in water without being stirred? 36 Unit A: Mix and Flow of Matter  SECTION REVIEW Assess Your Learning 1. Give an example of a pure substance. Why is it a pure substance? 2. Think about examples of solutions made by combining different states of matter. Make a chart like this one, and fill it in with an example of each combination. Substance Substance Solution Made Other Examples solid liquid table syrup solid solid steel liquid liquid perfume liquid gas tap water a) Which combination of substances was the most difficult to think of as a solution? b) Which combination was the easiest? 3. In paper chromatography, is the substance being tested the solute or the solvent? Explain your answer. 4. Use the particle model to explain what happens to the rate at which a solute dissolves when the temperature increases. 5. A bucket of paint spills on your classroom floor. How could you use your knowledge of dissolving to help clean up the paint? Focus SCIENCE AND TECHNOLOGY On Scientific knowledge may lead to the development of new technologies, and new technologies may lead to scientific discovery. Think back to the information on using paper chromatography to separate substances in a solution. 1. What do you need to know about pure substances and solutions in order to use paper chromatography technology? 2. Use the library or the Internet to find other applications of chromatography. 3. After finishing your research, consider the following statement. Then write a brief response to it. Understanding the scientific principles of paper chromatography is more important than developing uses for it. The Properties of Mixtures and Fluids Can Be Explained by the Particle Model of Matter 37  The properties of gases and liquids 3.0 can be explained by the particle model of matter. Key Concepts Most people think of liquids when they hear the word “fluids.” In this section, you will learn But gases are also fluids. A fluid is any matter that has no fixed about the following key shape—it takes the shape of its container. For example, the air in concepts: a bicycle tire takes the shape of the tire and water in a bottle takes properties of fluids the shape of the bottle. mass, volume, density Fluids have many properties that are useful. In this section, viscosity and flow rate you will investigate the fluid properties of viscosity, density, buoyancy buoyancy, and compressibility. Each of these plays a role in how a fluid may be used. For example, the Canadarm can move heavy Learning Outcomes objects using only gears while the space shuttle orbits Earth. On When you have completed this Earth’s surface, hydraulics provide an advantage that makes it section, you will be able to: possible for one person to lift and move huge loads. An engineer define viscosity and describe designing a hydraulic arm must understand how forces are how temperature affects it transmitted through a fluid and how fluids behave under calculate and compare pressure. You will have the scientific knowledge to design a densities and relate them to hydraulic arm at the end of this section. the particle model of matter describe methods of altering density in fluids explain buoyancy describe pressure and examples of its use compare the compressibility of liquids and gases 38 For Web links relating to 3.0, visit www.pearsoned.ca/scienceinaction 3.1 Viscosity and the Effects of info BIT Temperature One property of fluids is how they move or flow. Think about the fluids you have used in the last couple of days. What would happen if they didn’t flow the way they usually do? For example, what if soda pop was like a thick syrup or ketchup was like water? In both these situations, the properties of the fluids are very different. With your partner, identify three fluids that you have used, and describe what they would be like if they were thicker or What grade of motor oil is thinner. Here is an example: this? Multi-grade Engine Oil Fluid Thicker Thinner The Society of shampoo – hard to get out – would probably use Automotive Engineers of bottle more to wash hair (SAE) assigns all motor oils a viscosity number between 5 and 50. The How quickly fluids flow is a property called viscosity. It is higher the number, the determined by a fluid’s internal resistance or friction that keeps it higher the viscosity. from flowing. Recall from the particle model that the particles in a SAE 30 oil is suitable liquid slide around and roll over each other. In a gas, the particles for summer use, while SAE 10 oil can be used move around even more easily. The greater the friction or rubbing for winter driving. between particles in any fluid, the higher the viscosity. Fluids with Multi-grade motor oil, high viscosity do not flow as easily as fluids with a low viscosity. such as SAE 10W30, has compounds added to it that allow the oil to flow easily at cold temperatures, but Figure 3.1 Juice has a low viscosity. Ketchup has a high viscosity. prevent it from thinning out too much when the weather becomes hot. The Properties of Gases and Liquids Can Be Explained by the Particle Model of Matter 39  THE EFFECT OF TEMPERATURE ON VISCOSITY Earlier in this section, you thought about different fluids and what would happen if their viscosity changed. What might cause a fluid’s viscosity to change? Temperature is one factor that can have a big effect on viscosity. Look at Figures 3.2a)–d). What will happen to the viscosities of these fluids in the situations shown? Figure 3.2a) Table syrup Figure 3.2b) Hot tar spread Figure 3.2c) Olive oil placed Figure 3.2d) Room poured on hot pancakes on a road in a refrigerator temperature engine oil poured into a hot engine MEASURING VISCOSITY WITH THE RAMP METHOD The ramp method of testing viscosity involves pouring a fluid down a ramp and timing how long it takes to get to the bottom. By pouring the same amount of another fluid and timing it, you can compare the viscosities of different fluids. You can also investigate the effect of temperature on viscosity by testing the same fluid at different temperatures. First, you test it at room temperature. Then, you warm it in hot water or cool it in an ice bath, and test it again. G i v e i t a TRY A C T I V I T Y HOW FAST CAN IT GO? Materials & Equipment You will use the ramp test to determine the effect of shampoo Caution! pancake or table syrup temperature on the viscosity of four fluids. Handle hot water vegetable oil Design a fair test that will allow you to collect evidence to carefully. If you Teflon-coated cookie demonstrate the effect of temperature on viscosity. (See spill any on your sheet Toolbox 2 for more information on designing a fair test.) skin, immediately thermometer run cold water hot water Write a procedure and show it to your teacher for over the area. cold water approval. Then carry out your tests. beakers a stopwatch When you have completed your tests, create a one-page summary poster of your results. Include one graphic illustrating your results. 40 Unit A: Mix and Flow of Matter UNDERSTANDING VISCOSITY AND TEMPERATURE re SEARCH Recall that viscosity is a fluid’s internal resistance or friction that Fluids from the keeps it