Making smoke. What matter is Types and properties of matter How particles move in solids, liquids and gases

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1 Making smoke It s used at rock concerts, in nightclubs and even at weddings. The effect created when lights flash through the smoke from a smoke machine can be quite spectacular. But what is the smoke made from? It certainly doesn t smell like the smoke that is created by fire. Some smoke machines use the carbon dioxide we breathe out to help create the smoky haze. That s right, carbon dioxide! But the carbon dioxide used to make the smoke is different from the stuff we breathe out. Smoke machines use solid carbon dioxide, also known as dry ice. When water is added to the solid carbon dioxide, it quickly changes into a gas. The dry ice and the carbon dioxide gas are very cold. They cool the air around them so much that tiny droplets of water form in the air. The tiny droplets of water look like clouds, or smoke. 1 Are clouds made up of liquid or gas? 2 Is slime a solid or liquid? What matter is Types and properties of matter How particles move in solids, liquids and gases 3 Are there other materials that are hard to group as a solid, liquid or gas? 4 Do all solids form a liquid before they change into a gas?

2 States of matter verything around you is made of matter. Anything that has mass and takes up space is matter. The air we breathe, the water we drink and the food we eat are all different types of matter. But air, water and food are very different. One important difference between these items is their state. The three main states of matter are solid, liquid and gas. Gases change shape Gases fill the entire container they are in. The helium gas in balloons changes shape depending on the shape of the balloon. The helium fills every part of the balloon. Solids do not usually flow Most solids are too rigid to flow. Substances such as sugar, which are made up of many small solid pieces, can be poured. The volume of gases changes Gases expand to fill the containers they are placed in. Gases do not have a fixed volume. Solids have a constant shape Solids have a fixed shape and change shape only when a force is applied. The force applied to both ends of this bar by the circus strongman causes the bar to bend. Gases flow Like liquids, gases flow from one container to another. The gas from the helium bottle flows to the balloon through a tube. It is often hard to see gases flow because many of them are colourless. Gases can be compressed Gases can be squeezed so they take up less space (compressed). The gas inside the helium bottle is compressed. It expands when it leaves the bottle and fills the balloons. Solids and liquids cannot be compressed. 22 Science Alive 1 for VELS

3 Liquids have a fixed volume The liquid from the jug can be poured into several glasses. The total amount of space taken up in the glasses equals the amount that was originally in the jug. Liquids change shape A liquid s shape changes to fit the container it is in. The shape of the lemonade in these glasses depends on the shape of the glass. Liquids at rest have a flat surface. Investigating solids, liquids and gases You will need: a piece of dowel large plastic syringe water plasticine salt sponge. Copy the following table. Property Solid (dowel) Liquid (water) Gas (air) Fixed shape Fixed volume Able to be compressed Insert the dowel into the syringe. Press down on the plunger. 1. Can the dowel be compressed? Draw some water into the syringe. Put your finger over the end of the syringe and press down on the plunger. 2. Can water be compressed? Draw some air into the syringe. Put your finger over the end of the syringe and press down on the plunger. 3. Can air be compressed? Complete the remainder of the table by looking closely at the dowel and water, and by reading the captions on the circus scene. Investigate the properties of plasticine, salt and sponge. 4. Classify each of the three materials as a solid, liquid or gas. 5. Which materials did you have trouble classifying? Why? Liquids flow Liquids can be poured from one container to another. When the container is full, it overflows. Solids have a fixed volume If you move a solid from container to container, the amount of space it takes up (volume) is the same. REMEMBER 1. What properties do we use to classify materials into the three states? 2. Which state/s of matter: (a) can be compressed? (b) can flow? THINK 3. Classify each of the following items as a solid, liquid or gas. Oxygen Talcum powder Glass Vaseline Oil Honey Wood Sand 4. Why is a bicycle frame made of solids? Solids, liquids and gases learning 5. Why are bicycle tyres filled with air? OBSERVE 6. Look carefully at the circus scene on the left. (a) List as many solids, liquids and gases as you can find. (b) Find one example of a substance that can change from one state to another. I CAN: name the three states of matter describe the properties of the three states of matter classify materials as solids, liquids or gases.

4 Change of state W ater is the only type of matter that exists in all three states at normal air temperatures. Solid water (ice) is found in the form of icebergs and glaciers. Ice also falls from the sky during hailstorms. Liquid water (water) makes up our rivers, lakes and oceans. Water in the form of a gas (water vapour) is found in the air. Freezing The change of state from a liquid to a solid is called freezing. A liquid turns into a solid when heat is transferred away from it. Water freezes at 0 C. Melting The change of state from solid to liquid is called melting. A solid melts when heat is transferred to it. The melting point of water is 0 C. Sublimation occurs when a solid turns into a gas without first turning into a liquid. A change from gas to solid, without going through the liquid stage, is also called sublimation. Iodine, diamond and dry ice (solid carbon dioxide) are substances that sublime. Frozen carbon dioxide (dry ice) changes directly from a solid to a gas (sublimation). Condensing Condensation is the opposite of evaporation. If a gas comes into contact with a cold surface, it can turn into a liquid. Evaporating Evaporation occurs when a liquid changes to a gas. When water evaporates at temperatures less than 100 C, it forms water vapour. When it evaporates at temperatures greater than 100 C, it forms steam. Water vapour and steam cannot be seen. Boiling During boiling, the change from liquid to gas (evaporation) happens quickly. The change is so fast that bubbles form in the liquid as the gas rises through it and escapes. During boiling, the entire substance is heated. A liquid remains at its boiling point until it has all turned into a gas. The boiling point of water is 100 C. Melting and boiling points of some common substances Substance Melting point ( C) Boiling point ( C) Water Table salt Petrol Oxygen Aluminium Science Alive 1 for VELS

5 Go to worksheet 1.5 You will need: Changing the boiling point of water water Bunsen burner safety glasses ml beakers Copy the following table. heatproof mat thermometer salt matches retort stand sugar tripod boss head and clamp vinegar gauze mat teaspoon 100 ml measuring cylinder. Time (min) Temperature ( C) Tap water Salt water Sugar water Vinegar water Set up the equipment as shown below. Put on your safety glasses. Measure 100 ml of water with the measuring cylinder and pour it into the beaker. Measure the starting temperature of the water Boss head Clamp (time = 0 min). Light the Bunsen burner and place it under the beaker. Measure the temperature of the water every minute for 10 minutes. Record your observations in the table. After 10 minutes, turn off the Bunsen burner and allow the equipment to cool. Retort stand Box of matches Repeat the above steps with 100 ml of water with two teaspoons of salt stirred in, then 100 ml of water with two teaspoons of sugar stirred in, and lastly with 80 ml of water with 20 ml of vinegar stirred in. Thermometer Beaker Gauze mat Tripod Bunsen burner Heatproof mat 1. Draw a line graph of your results. Use a different coloured line for each water mixture. Plot time on the horizontal axis and temperature on the vertical axis. 2. How can you tell when the water has reached its boiling point? 3. Is there any part of the graph that shows the liquid has reached its boiling point? 4. What effect does adding substances to the water have on its boiling point? 5. What would happen to the temperature of each water sample if you continued to heat it past the 10-minute mark? Solids, liquids and gases learning REMEMBER 1. List the three states of matter. 2. Is heat transferred to a liquid or from a liquid during freezing? 3. What is the melting point of ice? 4. What is the boiling point of water? 5. Copy and complete the following flow diagram: Solid Liquid Evaporation Gas THINK 6. What is the difference between evaporation and boiling? 7. Describe a method for changing the boiling point of water. INVESTIGATE 8. At what temperature is: (a) oxygen a solid? (b) aluminium a liquid? 9. Find out how the melting point of water can be changed. I CAN: list the processes that result in a change of state describe the relationships between each state explain the difference between evaporation and boiling.

6 The particle model A ll matter is made up of tiny particles. If you could shrink down to microscopic size and watch these particles, you would see that the particles behave differently depending on whether the substance they make up is a solid, liquid or gas. To help explain this different behaviour, scientists have developed a model called the particle model of matter. Models help people understand complex ideas, such as how matter behaves. As new clues about matter have been discovered, the models have been improved. The basis of the particle model is that: All matter is made up of small particles. Particles are always moving. Particles are held together by bonds that vary in strength. As particles are heated, they move more quickly. When the particles are cooled, they move more slowly. Particles in a gas The forces between the particles in a gas are very weak. The particles are in constant motion. This means that gases have no fixed shape or volume. There are large spaces between the particles. The spaces allow the gas to be compressed. A gas can flow and diffuse easily since its particles are always moving. Gas particles have much more energy than solid and liquid particles. They move around and collide with other particles and the walls of the container they are in. Particles in a solid Solids cannot be compressed because the particles inside them are held closely together. There is no space between them. Bonds also hold the particles tightly together in a rigid crystal-like structure. This gives solids their fixed shape and constant volume. The particles in solids cannot move freely; they vibrate in a fixed position. This means that solids are unable to flow. Particles in a liquid The particles in a liquid are close together. So, there is no room for compression between the particles in a liquid. The particles are also held tightly by bonds, but not in the same rigid structure as solids. This gives liquids their fixed volume, but allows the particles to roll over each other. This rolling allows liquids to flow. The movement of the particles explains why liquids take the shape of their container. The particles roll over each other until they fill the bottom of the container. 26 Science Alive 1 for VELS

7 Diffusion Diffusion is the spreading of one substance through another. The spreading occurs because the particles of each substance become mixed together. The movement of the particles in liquids and gases makes diffusion possible. As the particles in a gas move faster than in liquids, diffusion happens faster in a gas. Particles are not free to move in a solid, so diffusion cannot occur at all. Air deodoriser The spreading starts in an area where there is a concentration of one of the substances. The particles keep mixing through until they are evenly spread through each other. Investigating diffusion You will need: 500 ml beaker water straw potassium permanganate crystals fragrant spray protective mat safety glasses. Using the straw as a Hold Crystal guide, put a crystal of straw potassium permanganate in the bottom of a beaker of water. Remove the straw Water and record your observations. Beaker 1. Draw a diagram of the movement of the potassium permanganate through the water. Release some of the fragrant spray in one corner of the classroom. Move away and observe by smell. 2. How do you think the fragrant spray moved through the air? 3. This experiment shows diffusion in a liquid (water) and diffusion in a gas (air). (a) Which state diffuses faster liquid or gas? (b) Why do you think this is? REMEMBER 1. What is the basis of the particle model? 2. What is diffusion? 3. Give an everyday example of diffusion at work. 4. Copy and complete the table at right. Property Solid Liquid Gas Particle arrangement Force of attraction between particles THINK 5. Why do solids have a fixed shape? 6. Why can gases be compressed? 7. Why do gases fill their containers? 8. When you pour cordial into water, the two liquids slowly mix together even though you don t stir them. Explain how this happens. Movement of particles Ability to diffuse Solids, liquids and gases learning I CAN: describe the particle model of matter describe how the particles move in each of the states: solid, liquid and gas explain how diffusion occurs in liquids and gases.

8 Change of state and the particle model magine a very cold day. On days like this, you probably sit inside without moving around too much. As the weather gets warmer, you start to move around a little more. On warm, sunny days, you probably have a lot more energy. On these days, you might feel like moving about more. Much like you, the particles inside matter also change the way they move when they are heated or cooled. Changing state A change of state involves the heating or cooling of matter. As a substance is heated, energy is transferred to it. When a substance cools, energy moves away from it to another substance or to the environment. The change in energy causes the particles in the substance to move at different speeds. Solid When a solid is heated, its particles start to move more quickly. The increased movement of its particles makes the solid expand. Melting As more heat is transferred to the solid, its particles vibrate more violently. Eventually the particles move so much that the bonds holding them in their fixed positions break. The particles start to roll over each other. Melting continues until the entire solid becomes a liquid. Liquid As a liquid is heated, its particles move and roll over each other faster and faster. The liquid begins to expand. Gas As in solids and liquids, the particles in gases move faster and faster when they are heated. The increased movement of the particles means that they take up more space and the gas expands. If the gas is heated in a closed container, the increased movement of the particles means that they collide more often with the sides of the container and with each other. Boiling If the liquid continues to be heated, the particles will eventually have enough energy to break the bonds holding them together. The particles can break away from the liquid and begin to move around freely. This process is called boiling. Boiling continues until the entire liquid becomes a gas. 28 Science Alive 1 for VELS

9 Foggy mirrors Have you noticed how the mirror in the bathroom fogs up after a hot shower? The fog is actually formed when water vapour that evaporates from the hot water cools down. Invisible gas Water vapour forms when particles in the hot water gain enough energy to escape and become a gas. You can t see water vapour. The particles in the water vapour move around freely. They have more energy than the particles in the liquid water. Fog in the air Some of the energy of the particles in the water vapour is transferred away from the vapour to the air. The transfer of energy leaves the water vapour with less energy so much less energy that its particles slow down. The transfer of energy away from the water vapour means it cools down and turns into tiny droplets of water. These tiny droplets form clouds. This process is called condensation. Fog on the mirror The energy from some of the water vapour is transferred to the cold mirror. This results in the water vapour condensing on the mirror. REMEMBER 1. What happens to the movement of particles as a substance changes from a solid to a liquid? 2. What happens to the movement of particles as a substance changes from a gas to a liquid? 3. Why do substances often expand when they are heated? THINK 4. The steel rails used in train tracks are placed end to end in a line to form each side of a train track. Gaps are left between the steel rails. Why do you think these gaps are left between the rails? Use the word expansion in your explanation Solids, liquids and gases 5. What is the relationship between the amount of energy the particles in a substance have and the state (phase) of the substance? 6. Explain why many substances contract when they are cooled. TEAMWORK 7. As a class, make a list of structures and substances around your home that undergo expansion and contraction. Divide your list into things that expand and things that contract. learning I CAN: describe what happens to the particles in a substance as it changes state explain why substances expand when heated. Checkpoint

10 Solids at work t s easy to see why solids have a fixed shape the particles are so tightly packed that they can only vibrate on the spot. However, it is possible to force solids to change shape! For example, heating, hammering, stretching and squeezing all affect the particles in a solid and cause it to change shape. Because solids sometimes change shape, architects and engineers must take the expansion, contraction and flexibility of materials into account when designing structures. For example, even though the Rialto Tower in Melbourne (the highest building in the Southern Hemisphere) is made of solids like concrete and steel, the top of it still moves up to 50 centimetres back and forth. Expanding solids All solids expand when heated, just as metal does when heated by a blacksmith. This can be both useful and a problem. Blacksmithing Many solids, especially metals, can have their shape changed. To do this, we take advantage of the properties of the solid. A blacksmith can take a block of metal and shape it into something useful. Expansion gap Expansion gap A blacksmith makes use of the properties of metal to shape it. Gaps must be left in railway lines and bridges to allow the metal to expand on hot days. Without the gaps, the railway lines would buckle out of shape. The blacksmith heats up metal in a fire to make the particles vibrate more quickly. A blacksmith uses tools like hammers to hit the softened metal and reshape it. The particles are moved around in the metal into new positions to make a new shape. Battery Siren Invar Copper Bimetallic strip bends up when heated. Fire alarms and fridge thermostats use a special strip made of two layers of metal. The strip is called a bimetallic strip. When heated, one metal (copper) expands more than the other (invar). In a fire alarm, the strip bends up when hot and completes the electric circuit, turning on the siren. When the particles vibrate faster, the bonds between them weaken, making the metal softer. The vibrating particles push each other further apart. This means they also take up more space, so the metal expands. 30 Science Alive 1 for VELS

11 Go to worksheet 1.6 A solid activity You will need: ball and hoop apparatus Bunsen burner tongs. Try to pass the ball through the hoop at room temperature. 1. Did it fit through the ring when it was cool? Heat the ball over the Bunsen burner and use the tongs to carefully try to drop the ball through the hoop while it is hot. 2. Did the ball fit when it was hot? 3. Use the particle model of matter to explain why this has occurred. 4. If the ball did not fit at room temperature, how could you make it fit? A solid selection There are many different solids. Different solids are used for different things depending on their properties. Some examples are given in the table below. Solid Properties Uses Concrete Hard, strong, long lasting Paths, buildings, walls PET (plastic) Ceramics Copper Aluminium Soft, flexible, strong, transparent Waterproof (if glazed), heatproof, strong, hard Easily shaped and stretched, unreactive, excellent conductor of heat and electricity Strong, easily shaped and stretched, light, unreactive Drink bottles Plant pots, kitchen tiles, roof tiles, heat tiles on space shuttle Electrical wiring, pots and pans, pipes for plumbing Aircraft, bicycles, engines, drink cans Diamond Very hard, transparent, strong Cutting tools, jewellery Wood Hard, strong, attractive, flammable Building, furniture, fuel in fireplaces learning REMEMBER 1. What happens to the particles in a solid when they are heated? 2. What properties of a solid allow a blacksmith to shape metals? 3. What is a bimetallic strip and what is it used for? 4. Draw a labelled diagram to show how a bimetallic strip would bend when heated. THINK 5. Explain, in terms of particles and bonds, why the concrete and steel in a skyscraper can bend. 6. Think of two other structures where gaps need to be left for expansion to occur on hot days. 7. Draw a diagram to show how power lines are hung with some slack between the poles. Redraw the diagram to show how they would hang on a hotter day. 8. For each material in group (a), select a matching property from group (b) and a use from group (c). (a) Marble, iron, gold, polystyrene (b) Easily shaped and attractive, light and soft, strong and hard, hard and attractive (c) Statue, jewellery, packaging, horseshoe I CAN: describe the properties of solids in terms of particles and bonds describe, in terms of particles, why solids expand when heated match the properties of solids to their uses Solids, liquids and gases

12 Liquids at work ave you ever noticed how many liquids you use every day? You may be surprised to know that liquids are everywhere! We depend on liquids in many ways because they have special properties that solids and gases don t have. Water can be moved using a siphon. Because water particles stick together (cohesion) they can pull each other along through the hose with a bit of help from gravity. The particles in water are small. They can fit between the tiny gaps in the material of our clothes and carry dirt away. What about water? You will need: water 500 ml beaker paperclip or needle. Make a paperclip or a steel needle float on water. 1. Record how you got the paperclip to float. Many things dissolve or float in water. This means that water can be used to carry away much of our waste. Water is carried in pipes. This is possible because water cannot be compressed, and the particles push each other along under pressure. When you place a thermometer in your mouth, the liquid inside it gets hotter. As the liquid gets hotter, the particles inside it move around more, taking up more space. The liquid expands and moves up the tube, showing a higher temperature. Hydraulic jacks use liquids (oil) to make it easier to lift heavy objects. Moving the jack handle pushes on the liquid in the hose. Liquids cannot be compressed, so the push on the liquid is passed along the length of the hose to a piston that causes the car to lift a short distance. The particles in oil are large and they can slide past each other. This makes oil slippery. Slippery liquids are called lubricants. Lubricants are used between moving parts to reduce wear. 32 Science Alive 1 for VELS Humans are made mostly of water. Most chemicals in our bodies are dissolved in water. The water is used to transport substances around our body. Chemical reactions inside us take place in water.

13 Water has surface tension. The particles on the surface of the water pull towards each other. The pull is strong enough to make the surface firm. The firmness is called surface tension. 2. Use this information to explain why some insects can walk on water. 3. Why does it hurt if you do a bellywhacker at the pool? Design an experiment to investigate what type of object can float using only the surface tension of the water. You may test shape, size, weight or type of material. Test some other liquids to see if their surface tension is stronger or weaker than water. Many fuels are liquids. The particles contain stored energy that can be released by burning in an engine. Water is used in an evaporative cooler. Hot air from the room passes over the water. The liquid water evaporates into a gas using the heat from the air. Energy from the air has been transferred to the water. The air is now cooler and is blown back into the room by a fan. Liquids expand when heated. When the liquid gets hotter, the particles move faster and take up more space. This is why a hot water system has an overflow pipe to release the pressure. Oils are used for cooking. Oils have large, heavy particles. They boil at higher temperatures than water, which means we can cook foods at temperatures higher than 100 C. The water in the glass goes up at the edges. This curving of the water s surface is called a meniscus. The particles in water are attracted to the glass. This is called adhesion. When we measure water in a measuring cylinder, we take the reading from the bottom of the meniscus Solids, liquids and gases learning REMEMBER 1. What is cohesion? 2. How does an evaporative cooler work? 3. What makes a lubricant like oil slippery? 4. Explain how a hydraulic jack works. 5. What property of liquids does a thermometer use? 6. Why do liquids expand when heated? THINK 7. How are the particles in oil different from those in water? 8. Explain why a liquid cannot be compressed. 9. Why can t gases be used in hydraulic machinery? 10. What does it mean if a chemical can dissolve in water? DESIGN 11. Design a machine that uses hydraulics to make a job easier. INVESTIGATE 12. Design an experiment to test one or two of the following things about a siphon. At what maximum length will a siphon hose stop working? How does the width of the hose affect the amount siphoned? How does the height of the higher container affect the speed of siphoning? What is the best angle for the siphon hose? I CAN: relate the uses of different liquids to their properties describe the differences between the properties of liquids and those of solids and gases.

14 Gases at work T he firefighter burst through the doors just in time, pointed the extinguisher at the electrical fire and pressed the trigger. A huge burst of carbon dioxide gas came squirting out of the nozzle, putting out the flames. Compressibility The carbon dioxide in the story above could be used in this way only because huge amounts of it can be compressed, or squeezed, into a container. Gases can be compressed because there is a lot of space between the particles. Gases compressed into cylinders are used for barbecues, scuba diving, natural gas in cars, and aerosol cans. Expansion Hot-air balloons work on the idea that gases expand when heated. The particles in the heated gas move about more and take up more space. This makes each cubic centimetre of hot air in the balloon lighter than each cubic centimetre of air outside the balloon, so it rises, taking the balloon with it. Fighting fire 4. When the nozzle is opened, the pressure forces the carbon dioxide gas out very quickly through the opening. 1. Gases, including carbon dioxide, have lots of space between their particles. 2. The carbon dioxide is compressed into the cylinder. The particles are squashed closer together. 3. The carbon dioxide particles are now under increased pressure. This means that the particles in the gas collide frequently with the walls of the cylinder. The particles push outwards on the walls of the cylinder. The particles are trying to escape, but are held in by the container. 5. The particles of gas quickly spread out over the fire. The gas smothers the fire, stopping oxygen from the air getting to it. Fires cannot burn without oxygen, so the fire goes out. 34 Science Alive 1 for VELS

15 Go to worksheet 1.7 Fizzing drinks All carbonated soft drinks contain carbon dioxide gas. The gas is dissolved in the liquid under high pressure. The gas stays dissolved in the liquid as long as the pressure inside the can is higher than outside the can. When the can is opened, it is de-pressurised and the carbon dioxide starts rising to the surface (because it is lighter than the liquid). In its hurry to escape, the carbon dioxide often pushes the top layer of liquid out as well, causing it to fizz and spill. Getting spaced out You will need: small balloon string ruler large beaker warm water cold water or fridge. Blow up the balloon until it is firm. Measure the circumference of the balloon with a piece of string and record your results in a table. Put the balloon in warm water for 10 minutes and re-measure the circumference. 1. Did the balloon expand or contract? Put the balloon into the cold water or a fridge for 10 minutes and measure the circumference of the balloon again. 2. Did the balloon expand or contract? 3. In terms of particles, explain what happened when the balloon was heated and cooled. Well-known gases There are many gases we use for different purposes. Here are some of the more well-known ones. Famous gas Use Property Neon Neon lights Absorbs electrical energy and turns it into light Helium Methane (in natural gas) Party balloons, blimps Cooking, heating Lighter than air Flammable Argon Fluorescent lights Absorbs electrical energy and turns it into light Ozone Nitrous oxide (laughing gas) Cleaning water in pools and spas Anaesthetic Highly reactive; kills bacteria Affects nervous system in humans Solids, liquids and gases REMEMBER 1. Why can gases be compressed? 2. What happens to a gas that is heated? 3. Explain how a carbon dioxide fire extinguisher works. THINK 4. Draw a diagram of a gas before and after heating to show what happens to the particles. 5. Why do aerosol cans have Do not dispose of in fire printed on the can? 6. Explain which would last longer: a scuba diver s tank filled with compressed air or one filled with air at normal pressure. 7. Explain what would happen to the pressure in a car tyre after it has been driven on a hot road, and then parked on some cool grass. INVESTIGATE 8. Many gases, including oxygen, nitrogen, chlorine and hydrogen, have important uses. Choose one of these gases and find out what it is used for and why. 9. Find out what gases are found in the air and how much of each gas there is. 10. Many gases in the air are pollutants put there by humans. Find out about what problem one of the following gases causes to the environment: sulfur dioxide, chlorofluorocarbons (CFCs), nitrogen dioxide, or ozone. I CAN: learning explain what happens to a gas when it is compressed or when it expands explain how a fire extinguisher works relate the uses of different gases to their properties.

16 Check and challenge Solids, liquids and gases Testyourself The particle model of matter 1. List the four principles behind the particle model. 2. What is matter? Properties of solids, liquids and gases 3. Copy and complete the table below to summarise the properties of solids, liquids and gases. Property Solid Liquid Gas Has a fixed shape Has a fixed volume Able to flow Able to diffuse Able to be compressed Space between particles Particle movement 6. (a) What happens to the movement of particles in a substance when it changes state from a solid to a liquid? (b) What happens to the bonds between the particles in this process? 7. In which state solid, liquid or gas do the particles have the: (a) most energy? (b) least energy? 8. Describe two ways to change the speed at which particles move in a liquid. 9. Draw a diagram to show what happens to the particles inside a balloon that is placed in the refrigerator. 10. Describe the difference between boiling and evaporating. 11. Explain how and why water forms on the outside of a cold soft-drink bottle on a warm day. Use diagrams to help with your explanation. 12. (a) What does sublimation mean? (b) Give an example of a substance that sublimes. 13. Which of these diagrams (A, B or C) correctly shows a solid after expanding? Bonds between particles 4. Fully explain the process that is occurring in the following diagrams. Original solid 5. Complete the following diagram by labelling the arrows: Solid Liquid Gas A B C 36 Science Alive 1 for VELS

17 Matching the properties of a substance to its use 14. (a) Copy out this table and rewrite it to correctly match the substances to their properties and uses. (b) State whether the substance would be a solid, liquid or gas. Name of substance Property Use Air Tin Neon Waterproof, hard, strong Particles able to mix easily with other particles Particles absorb energy and turn it into light Horseshoe Balloon Sign, light Oil Hard, strong Driveways Iron Concrete Hard, strong, easily shaped when heated Particles slip past each other Lubricant Roofing 15. Suggest a reason why bridges have gaps between the blocks they are constructed from. 16. Decide whether each of the following statements is true or false. If the statement is false, explain why. (a) The compressibility of gases makes carbon dioxide useful in a fire extinguisher. (b) Gases expand when cooled. (c) Water particles stick together. This is called adhesion. (d) Solids are hard because the particles are close together. (e) Fuels have energy stored in the bonds between particles. Solid, liquid or gas? Cars 1. A car is constructed from solids, liquids and gases. (a) List the solids, liquids and gases found in a car. (b) Why don t cars have solid tyres? (c) Why don t cars use solid fuel? (d) How could cars that work on gas carry enough fuel? 2. Rob pumped up his tyres on a cold day. A week later, the weather warmed up and Rob decided to go for a long drive. He noticed that the pressure inside the tyres had changed from when he had first pumped them up. Would the tyre pressure have increased or decreased after the long drive? Explain fully. 3. Separate the following substances into solids, liquids and gases. Gold Fairy floss Helium Slime (see page 21) Glass Milk DVD Kitchen sponge Neon If you need help, try researching in the library or on the Internet. Designer substances 4. Imagine you are a scientist in charge of developing new materials. The Australian Space Agency has approached you because they need a new substance to coat the outside of the space shuttles they are designing. The substance must be: able to withstand the heat of the shuttle re-entering the Earth s atmosphere flexible enough to bend when the wings of the shuttle bend strong enough to stand the vibration of take-off, landing and other movement light enough to be part of a flying spacecraft resistant to chemical attack able to reflect the solar radiation in space. Your task is to design the coating for the space shuttle. Include: (a) whether it will be solid, or an innovative liquid or gas coating. It could be a combination of these in layers or as a mixture. (b) how the coating of substances will work to meet the criteria from the Australian Space Agency. This will include the properties of your substances and how they are put together. (c) a drawing of your coating indicating its special features and how it works Solids, liquids and gases

18 Summary of key terms adhesion: the attraction between particles of one substance to particles of another object or substance bimetallic strip: a strip constructed from two different metals. Each of the metals must expand at a different rate. Bimetallic strips are often used in thermostats. Battery Invar Copper Siren Bimetallic strip bends up when heated. boiling: the change of state from a liquid to a gas. Boiling occurs when the entire liquid is heated and continues until the liquid turns completely into a gas. bonds: the forces that hold particles (atoms) together cohesion: the ability of particles to stick together and pull each other along compressed: squeezed into a smaller space. Gases can be compressed, but liquids and most solids cannot be compressed. condensation: formation of liquid when a gas cools down. Condensation occurs on bathroom mirrors and on the outside of softdrink bottles. condensing: the change of state from a gas to a liquid contract: become smaller in size diffuse: spread throughout another substance diffusion: the spreading of one substance through another due to the movement of their particles dissolved: describes a substance that has mixed completely with another so that it is no longer visible evaporation: the change of state from a liquid to a gas. Evaporation occurs only from the surface of the liquid. expand: increase in size due to the movement of particles in the substance force: a push, pull or twist freezing: the change of state from a liquid to a solid fuel: substance that burns to produce heat gas: state of matter with no fixed shape or volume hydraulic: describes a machine that uses liquids to exert a push (force) from one place to another. Hydraulic machines use liquids because they cannot be compressed. liquid: state of matter that has a fixed volume, but no fixed shape lubricants: substances with large particles that can slide easily over each other. Lubricants are used between surfaces that rub against each other. Lubricants reduce wear and increase the motion between the surfaces. melting: the change of state from a solid to a liquid meniscus: the curved upper surface of a liquid. The curve forms when particles in the liquid stick to the sides of the container they are in. mixture: substance made up of two or more elements, two or more compounds, or a combination of elements and compounds. The elements or compounds in a mixture are not bonded together. particle model of matter: a model that explains the behaviour and properties of each of the states of matter particles: the individual parts that make up all matter. (These particles are called atoms.) pressure: the push of a substance against another. For example, a gas exerts pressure on the container it is in because the particles in the gas collide with (push on) the sides of the container. rigid: stiff, not flexible siphon: a device that uses gravity to move a liquid from one place to another solid: state of matter that has a fixed shape and volume state: the condition of a substance. The three main states of matter are solid, liquid and gas. A state is also known as a phase. sublimation: the change in state from a solid into a gas without first becoming a liquid (or from a gas into a solid without first becoming a liquid). surface tension: the firmness of the surface of a liquid created by the attraction between particles at the surface of the liquid transferred: moved from one place to another volume: the amount of space taken up by an object or substance water vapour: water in its gas state. The temperature of the water is less than 100 C when it forms water vapour. 38 Science Alive 1 for VELS