Kareem Science Unit 3 - States of Matter PDF

3 States and properties of matter 3.1 Gases We are going to... learn that some substances are gases learn about the particle model of matter for solids, liquids and gases find out about the gases in air find out that some substances in the ai...

3 States and properties of matter 3.1 Gases We are going to... learn that some substances are gases learn about the particle model of matter for solids, liquids and gases find out about the gases in air find out that some substances in the air cause pollution make a prediction about air pollution use results to say if the prediction was accurate record results and observations in drawings and tables draw a dot plot of results Getting started Look at the picture of Zara’s birthday party on the next page. 1 a Find all the solids liquids, and gases shown in the picture. b Write three lists, one for the solids, one for the liquids and one for the gases you observed in the picture. 2 How did you decide if something was solid, a liquid or a gas? 58  3.1 Gases Gases around us atmosphere compressed Gases are all around us, for example air. Gases are invisible layer also in fizzy drinks and inside bicycle and car tyres. We don’t always know that gases are there because pollute pollution we can’t see most gases. These gases are invisible. properties structure We also can’t smell or taste many gases around us. Activity Where is the air? You will need: a bowl of water and an empty plastic bottle, a balloon or paper bag 1 a Is the bottle really empty? Do you think there is anything inside the empty bottle? b Hold the empty bottle under the surface of the water. Make sure the lid is off. What do you see? Say why you think this happened 2 a Blow into the paper bag or balloon. What happens? b What is inside the bag or balloon? How do you know? 3 Talk about what you have learned about air from this activity. 57  3 States and properties of matter Sometimes we can see when gases form. Think like a scientist 1 Make a gas You will need: vinegar, bicarbonate of soda, a jar with a wide mouth, a spoon When we mix some materials, they react to make a gas. You are going to make carbon dioxide gas. Pour some vinegar into the jar. Vinegar Put a teaspoon of bicarbonate + Bicarbonate = Carbon dioxide of soda of soda into the jar. Observe what happens. Questions 1 What state of matter is: a vinegar? b bicarbonate of soda? c the new substance that forms? 2 a  raw a picture to show what happened when the bicarbonate D of soda mixed with the vinegar. Label the liquid and the gas. b Write a sentence to describe what happened when you mixed the bicarbonate of soda with the vinegar. How am I doing? Point to one of the faces to answer the questions. or or Was I able to follow the instructions? Did I observe a gas and draw my observations? Could I write a sentence to describe my observations? 58  3.1 Gases The particle model of matter In Stage 4 you learnt that solids, liquids and gases are all made up of particles that move. The particle model of matter describes the structure of solids, liquids and gases and explains their properties. Solids In solids, the particles are very close together. There are small spaces between the particles. The particles are packed together in a regular pattern. They cannot move or vibrate freely or fast because they are held together so tightly. They vibrate in a fixed position only. This explains why solids, such as bricks, have a fixed shape and cannot be squashed The particles in a solid or compressed. Liquids In liquids, the particles are closely packed but further apart than in solids. There are small spaces between the particles. The particles are not packed in a fixed pattern. Because the particles are not held together so tightly, they can move or vibrate faster and more freely. The particles in liquids can slide past one another. This explains why liquids, such as water, can flow and take on the shape of the The particles in a liquid container they are in. Gases and the particle model Some substances are gases. In gases, the particles are very far apart from each other. There are big spaces between the particles. The particles can move freely in all directions and move very fast because they are not held together strongly. This explains why gases, such as air, have no shape of their own at all. The particles in a gas 59  3 States and properties of matter Think like a scientist 2 Describe solids, liquids and gases 1 Draw the particle model for each of these states of matter of water: a water b water vapour c ice. 2 In which state of matter: a are the particles very close together? b are the particles very far apart? c do the particles move fast in all directions? d are the particles close together but not packed in a fixed pattern? 3 What does the particle model show us about the structure of solids, liquids and gases? 4 Explain why we can squash a gas, but we cannot compress or squash a solid. Atmosphere Air Air is a mixture of different gases. A gas called nitrogen makes up about four-fifths of the air. Air also contains a gas called oxygen. We need oxygen to live. We breathe in oxygen. We breathe out a gas called carbon dioxide, which is also found in air. Air also contains a gas called water vapour. The layer of air that surrounds the Earth is called the atmosphere. There are many other gases that are not found in air, for example such as hydrogen and helium. 60  3.1 Gases Air pollution It is also important for us to have clean air to breathe. In many places in the world, the air is not clean. People put smoke, dust and gases from factories, power stations, cars, trucks and aeroplanes into the air. These substances make the air dirty and harmful to living things. We say that they cause air pollution. Air pollution is not only outside. Homes, schools and buildings can also have air pollution. Many things that people use every day can pollute the air. Smoke from cigarettes and cooking, and fumes from spray cans and paints also pollute the air. Air pollution can make us cough, feel dizzy and give us headaches. People who breathe in polluted air also often suffer from breathing problems. The smoke from cigarettes can cause serious diseases that harm our lungs. 61  3 States and properties of matter Think like a scientist 3 Measure air pollution You will need: five pieces of white or clear plastic, petroleum jelly, a marker pen, a ruler, tape, a box On one side of each piece of plastic, use a marker pen to mark an area that is 4 cm long and 2 cm wide. Put the pieces of plastic in five different places, for example your classroom, the schoolyard, a garage, a park, on a lamppost and in a kitchen. Cover the marked area of each piece of plastic with a thin layer of petroleum jelly. Tape the pieces of plastic in place. Predict which place will have the most polluted air. Give a reason for your prediction Leave the piece of plastic for three days. Then carefully put the piece of plastic in a box and bring them to school. Do not touch the petroleum jelly. Observe the amount of air pollution in each marked area. Make a drawing of each piece of plastic to show the amount of pollution on it. Number the drawings in order of the amount of pollution on the pieces of plastic. The piece of plastic with the least pollution will be number 1. The piece of plastic with the most pollution will be number 5. Write a number under each drawing. Record your results on a table like the one below. Piece of plastic Place it was put Amount of pollution observed A B C D E 62  3.1 Gases Continued Draw a dot plot of your results. Was your prediction correct? Which place had the most air pollution? Which place had the least air pollution? Suggest a reason for this. Did I do my best? Did I ask for help if I needed it? What can I do better next time? Have I changed any ideas I used to have about gases? Look what I can do! I can name some substances that are gases. I can describe the particle model of matter for solids, liquids and gases. I can say which gases are in air. I can understand that some substances in the air cause pollution. I can make a prediction about air pollution. I can use results to say if the prediction was accurate. I can record results and observations in drawings and tables. I can draw a dot plot of results. 63  3 States and properties of matter 3.2 Properties of water We are going to... investigate the properties of water learn that most water on Earth has dissolved substances in it measure temperature identify safety risks in an investigation and work safely record measurements in a table draw line graphs of results find information to answer a scientific question Getting started 1 Have you ever boiled water to make a cup of tea or to cook food? What makes the water boil? 2 How do we know when the water is boiling? 3 What is steam made from? Point to the steam in the picture. 4 Draw and label a picture of water boiling in a pan. boil expand steam boiling point melt temperature contract melting point thermometer 64  3.2 Properties of water Water changes state Solids, liquids and gases are different states of matter. Water exists in all three states of matter. Ice is solid water. The water we drink is a liquid. Water vapour in the air is a gas. Water changes state when it is heated or cooled. For example, when we heat ice, it melts to form liquid water. When solids, like ice, are heated, their particles gain energy and start to move more quickly and pull further apart. If the particles gain enough energy, they move further apart from each other. The solid becomes a liquid. When a solid changes into a liquid we say the solid melts. We can show how melting happens like this: solid + heat → liquid If we heat water enough, it will boil. When water boils it forms bubbles of a gas called steam. Steam is heated water vapour. The particles of the liquid gain heat and move much more quickly. Some of the heated particles move far apart and become a gas. This happens throughout the liquid, not just on the surface. We can show how boiling happens like this: liquid + heat → gas Melting and boiling points All substances melt and boil. Different substances take different times to melt or boil because it takes different amounts of heat for them to change state. The amount of heat in a substance is called the temperature. We measure temperature with a thermometer. The unit we use is degrees centigrade (°C). 65  3 States and properties of matter Think like a scientist 1 Investigate ice melting You will need: a thermometer, a cup of water, four or five ice cubes, a spoon Place the thermometer in the cup of water. Wait for about two minutes. Measure and record the water temperature in a table like this one. Time in minutes Water temperature in °C Take the thermometer out of the water. Add the ice cubes and stir with the spoon. Repeat the first two steps. Measure and record the water temperature every two minutes until all the ice has melted. Draw a line graph of your results. Questions 1 a What did you notice about the temperature of the water up to the time when all the ice had melted? b Explain why this happened. 2 a How many minutes did it take for the all the ice to melt? b What was the temperature of the water when all the ice had melted? 3 How do you think your results would change if you heated the water in the investigation? 4 Ice melts at the same temperature at which water freezes. Why do you think this so? 5 Which type of scientific enquiry did you use in the investigation? How am I doing? Answer ‘well’, ‘quite well’, or ‘I need help’ to these questions: How well can I use a thermometer to measure temperature? How well can I record measurements in a table? How well can I draw a line graph of results? 66  3.2 Properties of water Like other substances, water needs to reach a certain temperature in order for its physical state to change. The temperature at which a substance melts is its melting point. This is when it changes from a solid to a liquid. The melting point of ice is 0°C. Water freezes at 0°C. This means that the melting point of ice is the same as the freezing point of water. Think like a scientist 2 Is the melting point of ice always the same? Do you think ice always melts at the same temperature? Are there any factors that can change the melting point of ice? Do some research to find out. The temperature at which a substance boils is its boiling point. This is when it changes from a liquid to a gas. Melting point and boiling point are properties of substances. They do not change unless the substance itself changes. 67  3 States and properties of matter Think like a scientist 3 Investigate the boiling point of water You will need: a thermometer, water at room temperature, a beaker or small saucepan, a hot plate or Bunsen burner, tongs Pour some water into the beaker or saucepan and follow these steps: Place the thermometer in the cup of water. Wait for about two minutes. Measure and record the water temperature in a table like this one. Time in minutes Water temperature in °C Your teacher will heat the pan or beaker of water on the hot plate or Bunsen burner. Identify any safety risks that you can think of. Measure and record the water temperature every two minutes until the water boils. Say how you can do this safely. Measure and record the temperature of the water every two minutes for another four minutes after the water boils. Draw a line graph of the results. Be careful not to touch the beaker or hot water when you measure the temperature. Questions 1 a How many minutes did it take for the water to boil? b Would the amount of time for the water to boil be different if you used less water? Say why or why not. 2 a At what temperature did the water boil? b Would this temperature be different if you used less water? Say why or why not. 3 What are the bubbles in the boiling water? Why do you think they form? 4 The boiling point of pure water is 100°C. Did you measure this temperature? If not, suggest a reason why the temperature you measured was different 68  3.2 Properties of water °C 120 °C 120 100 100 80 80 60 60 40 40 20 20 0 0 –20 –20 Pure water freezes Pure water boils when when the temperature the temperature drops to 0°C. reaches 100°C. The boiling point of pure water is 100°C, but most of our water has small amounts of other substances mixed with it. This makes the water boil at a slightly different temperature. Water also boils at a lower temperature the higher we are above sea level. Water expands We know from the particle model of matter that when a substance gains heat its particles move faster and spread out. This makes the substance take up more space. We say that the substance expands. When the substance cools down, its particles move more slowly because they have less energy and move closer together. The cooled substance takes up less space. It gets smaller, or contracts. Heated particles move Cooled particles move more faster and further apart slowly and closer together Water does not always boil at 100°C. Why is this so 69  3 States and properties of matter Activity Observe changes when water freezes You will need: a plastic bottle with a lid, such as a milk bottle; a freezer; water Half fill the bottle with water. Close the bottle with lid. Put the bottle in a freezer overnight. Predict if you think the water will expand or contract? Say why you think this. Observe the bottle the next day. Describe the change that has taken place. Water does not always behave like other substances. When we freeze or solidify water, it does not contract as we would expect. Instead it expands. This property of water also allows ice to float. How did the practical work help me to learn about the properties of water? What do I need to practise more? Look what I can do! I can investigate the properties of water. I can understand that most water on Earth has dissolved substances in it. I can measure temperature I can identify safety risks in investigation and say how to work safely. I can record measurements in a table. I can draw line graphs of results. I can find information to answer a scientific question. 70  3.3 Evaporation and condensation 3.3 Evaporation and condensation We are going to... learn about and investigate evaporation and condensation use the particle model to explain evaporation and condensation use scientific knowledge to make a prediction use results to say if predictions are correct suggest a way to improve an investigation identify variables in a fair test investigation condensation make a drawing of observations evaporate learn about processes in the water cycle evaporation make a model to show the water cycle precipitation reverse Getting started water cycle Work in a group. You will need: a glass of water, sheet of paper towel Dip your finger into the water. Make a wet spot on the paper with your finger. Leave the paper for a few minutes. Pick up the piece of paper and feel it. Answer these questions: 1 Is the paper wet or dry? 2 What did you do to help get rid of the water spot? 3 If the water is not on the paper, where did the water go? 4 How can what you observed be helpful to people? 71  3 States and properties of matter Evaporation When water or other liquids become warm enough, they change into a gas. Water changes into a gas called water vapour. When particles on the surface of a liquid change into a gas, we say the liquid evaporates. Evaporation happens all around us without us noticing it much, like a puddle drying up or washing getting dry. Evaporation happens because some particles in the liquid gain heat energy. The heated particles start to move faster and move further apart. Eventually the heated particles move so far apart that they escape from the surface of the liquid into the surrounding air. When a liquid evaporates it changes from the liquid state to the gas state. liquid + heat → gas Think like a scientist 1 Investigate evaporation You will need: two identical glasses, water, a permanent marker, a measuring cup or cylinder Measure and pour 100 ml of water into both glasses. Mark the level of the water in the glasses with a permanent marker. Put one glass in a warm place. Put the other glass in a cool place. Leave the glasses for two days. Predict the results you expect to obtain. Say why you made this prediction. Mark the level of water in both glasses after two days. 72  3.3 Evaporation and condensation Continued Questions 1 Was the water level in the two glasses the same after two days? 2 a  Which glass had the most water and which glass had the least water after two days? Was your prediction correct? b Use the particle model to explain your observations. 3 Suggest a way you can improve the investigation to find out how much water evaporated from both glasses. 4 Why does washing dry quicker on a hot day? Condensation Activity 1 Breathing out Work with a partner. 1 Breathe onto your hand. Does your breath feel warm or cold? 2 a  Breathe onto a window pane or a mirror. What do you observe? b Why do you think this happens? The air you breathe out is warm. It contains water vapour gas. When the warm air touches a cooler surface like the mirror it cools down. If the surface is cold enough, the water vapour gas changes to drops of liquid water. The process is called condensation. It is the reverse of evaporation Condensation happens because the particles of a gas lose energy when they get cooler. This makes them slow down and move closer together to become a liquid. 73  3 States and properties of matter Think like a scientist 2 Investigate condensation You will need: two identical glasses, ice, water, a measuring cup, a cloth Look at the picture to see how to set up your investigation. Wipe both the glasses with a cloth. Leave the glasses for 15 minutes and then observe them. Make labelled drawings of your observations. Questions 1 a  hich variable did you observe or measure? W What is this type of variable called? b Which variables did you keep the same? What is this type of variable called? c Which variable did you change? What is this type of variable called? d Was this a fair test? Say why or why not. 2 Use the particle model to explain your observations. 3 Condensation is the reverse of evaporation. Explain why this is so. How am I doing? Choose a card to answer the questions. I get it! I can even explain to others. I need a little more help. I don’t get it. I need a lot of help. How well can I identify different variables in an investigation? How well can I use the particle model to describe condensation? How well can I say why condensation is the reverse of evaporation? 74  3.3 Evaporation and condensation Activity 2 Make a flow chart of change of state Make a flow chart to show the different changes of state of matter. Use the words in the box. gas solid liquid melting evaporation freezing condensation For each of these changes of state, state whether heating or cooling happens. Melting    Freezing    Condensation    Evaporation The water cycle Water keeps going around and around in what we call the water cycle. In the water cycle, water moves from the land and sea to the air and back again. 75  3 States and properties of matter The water cycle happens mainly because of evaporation and condensation. Freezing and melting can also happen in the water cycle. The rain and snow that fall from clouds onto the Earth are called precipitation. Sometimes balls of ice called hail also fall from the clouds. Questions 1 a  Where does the heat come from to make water evaporate from rivers, lakes and seas? b Where else on the drawing does evaporation happen? 2 Where does the evaporated water go? 3 a What happens to water vapour when it condenses? b Where in the drawing does this happen? 4 How does the evaporated water get back to Earth? 5 Where in the water cycle can: a freezing happen?   b melting happen? 6 Complete these sentences about the water cycle. Use the words in the box to help you. precipitation condenses evaporates water water vapour rain a Water on the Earth’s surface ____________ and moves up into the air as ________ b The water vapour cools and ___________ as it rises into the air. c ___________, snow and hail are forms of ____________ that bring __________ back to the Earth’s surface. 7 Why is the water cycle important to us? Think like a scientist 3 Make a model of the water cycle You will need: a glass or clear plastic bowl, a small dish which will fit inside the bowl, water, clear plastic wrap or a sheet of clear plastic and an elastic band, a small stone 76  3.3 Evaporation and condensation Continued Place the dish inside the bowl. Pour some water into the bowl around the dish. The water should be about 1 cm deep. Make sure no water splashes into the dish. Put the plastic wrap over the bowl and stick it down. Or put the sheet of plastic over the bowl and hold it down with the elastic band. Put the small stone on the plastic. Leave the bowl outside in a warm, sunny place for a few hours. Questions 1 a Describe what you observed in your model after a few hours. b Why did this happen? 2 Say how your model shows the different parts and processes in the water cycle. What did I do well in this topic? What could I do better next time? Look what I can do! I can describe and investigate evaporation and condensation. I can use the particle model to explain evaporation and condensation. I can use scientific knowledge to make a prediction. I can use results to say if predictions are correct. I can suggest a way to improve the investigation. I can identify variables in a fair test investigation. I can make a drawing of observations. I can describe the processes in the water cycle. I can make a model to show the water cycle. 77  3 States and properties of matter 3.4 Solutions We are going to... investigate and describe dissolving decide if a solid is soluble or not learn that soluble and insoluble substances cause water pollution investigate how to separate a solution make drawings of observations measure liquids choose and use equipment in an investigation decide on the type of scientific enquiry to use to investigate a question learn that dissolving is a reversible process ask a question to investigate and find the answer Getting started The pictures show different mixtures. How can you separate each mixture? a peanuts and raisins b sand and water c rice and flour Discuss this as a class. d tea leaves and water e iron filings and rice dissolve pesticides solute uniform fertilisers reversible solution universal insoluble soluble solvent 78  3.4 Solutions Dissolving and solutions Tea is a liquid. Sugar is a solid. When you put sugar in your tea and stir it, the sugar seems to disappear. You know the sugar is there because you can taste it in the tea. What happened to the sugar? The sugar has dissolved in the tea. This means that the particles of sugar have spread out into the spaces between the particles of the tea. Solids that can dissolve in a liquid are called soluble solids. Being able to dissolve is a property of the solid. Not all solids can dissolve. These solids are insoluble. Mixtures are made of particles of different substances mixed together. Dissolving is a type of mixing because when the solid dissolves it mixes with the liquid. We call the mixture a solution. The solid in the solution is called the solute, for example sugar. The liquid is called the solvent, for example tea. Being able to dissolve a solid is a property of the liquid. A solution will always contain a solute and a solvent. Sea water is another solution. The salt dissolves in the water to make the solution. The salt is the solute and the water is the solvent. Many substances dissolve in water. This is another one of water’s properties. Water is sometimes called the universal solvent because so many substances can dissolve in water. Water pollution Some solutions can be harmful. Some soluble substances can pollute water. We cannot see these substances because they are dissolved in the water, so we don’t know that the water is polluted. Polluted water can harm plants, animals and people. Dissolved chemicals, such as acids, from factories can pollute rivers and lakes. Farmers put chemical fertilisers in the soil to make their crops grow better. These fertilisers sometimes wash into rivers and pollute the water. 79  3 States and properties of matter Many farmers also spray chemicals on their crops to kill pests like insects. These chemicals are called pesticides. They can also pollute natural water sources when they dissolve in rainwater and get washed into rivers and the sea. Insoluble substances in water can also cause pollution. Examples include human body waste, oil and plastics. Questions 1 What is dissolving? 2 a Can all solids dissolve? b How do we know if a solid has dissolved? 3 a Name the two parts of a solution. b Give an example of each of the two parts. 4 Why is a solution a mixture? 5 Why is water sometimes called the universal solvent? 6 Why can’t we sometimes see water pollution? 7 a Name two soluble substances that cause water pollution. b Name two insoluble substances that cause water pollution. 8 How do you think the use of pesticides affects the environment? 80  3.4 Solutions Think like a scientist 1 Make a solution You will need: water, coloured crystals, a glass jar, a teaspoon, a measuring cylinder, a watch Do not touch or taste the crystals. Measure and pour 100 ml of water into the jar. Put a teaspoon of crystals into the jar and observe what happens. Describe what you observe in the water around the crystals? Draw and label your observations. Wait five minutes. Can you see the solid crystals any more? In this activity, which substance is the solute and which is the solvent? Which type of scientific enquiry did you use in the investigation? The particles of the solute move between the solvent particles when they dissolve. The solute particles spread evenly in the solvent. Because of this you cannot see the solute in a solution after it has dissolved. We say that a solution has a uniform appearance – it is the same throughout. This means that it looks the same throughout. The picture shows how the solute particles spread when they dissolve in water. Water particles Salt and water particles are Salt evenly spread dissolves Solute particles (e.g. salt) 81  3 States and and properties propertiesof ofmatter matter Activity Is it a solution? 1 With a partner, decide if each of the pictures of mixtures shows a solution. Say why or why not. Coffee and Sand and Flour and Cooldrink powder hot water water water and water 2 Which substance is the solvent in the solutions? 3 Which of the solids in the mixtures are soluble? 4 What other solutions can you think of? How are we doing? Ask your partner these questions: Can you identify solutions? Can you say why it is a solution? Can you identify soluble solids? Can you think of any other solutions? Your partner will hold up fingers to answer the questions. 1 finger = I can’t do it 2 fingers = I can do some of it 3 fingers = I can do it all 82  3.4 Solutions Separating a solution A solution is a mixture of the solute and the solvent. We can separate most mixtures because the particles of the substances in the mixture are not chemically joined together. Can we separate a solution? Think like a scientist 2 How can we get back the salt? Most of the salt we put on our food comes from sea water. Sea water is a solution. How can we get salt from sea water? Use your knowledge of evaporation to plan how to get solid salt from a salt solution. Think about these questions: – What materials and equipment will you need? – Which type of scientific enquiry will you use? – What will you do? – Where should you set up the investigation? – How long must you leave it to get any results? Carry out the investigation. Make a labelled drawing to show what you used and what you did. Make a labelled drawing to show the results of your investigation. Questions 1 A solution is a mixture. Say how your results show this. 2 Complete this sentence to write a conclusion: I found out that it was possible/impossible to separate a solid from a liquid by evaporation. 3 Suggest one way you could obtain results faster. How are we doing? or or Could we choose suitable materials and equipment to use? Did we work together to plan and carry out the investigation? Did we use a suitable method to get back the salt? 83  3 States and properties of matter We can separate the dissolved solute from a solution by evaporation. We call this a reversible process because we can get back the dissolved solute from the solution. Think like a scientist 3 Ask and investigate a question With a partner, think of a question about dissolving and solutions that you would like to find the answer to. Decide on the type of scientific enquiry you will use to answer your questions, for example, a fair test, doing research, pattern seeking or observing over time. Find out the answer to your question. Make a presentation to share with the class about your findings. What did I learn about myself in the different activities? Am I happy with the work I did? Look what I can do! I can investigate and describe dissolving. I can say if a solid is soluble or not. I can understand that soluble and insoluble substances cause water pollution. I can investigate how to separate a solution. I can make drawings of observations. I can measure liquids. I can choose and use equipment in an investigation. I can decide on the type of scientific enquiry to use to investigate a question. I can say why dissolving is reversible process. I can ask a question to investigate and find the answer. 84  Project Project: How do people use evaporation? Evaporation happens when a liquid changes into a gas. Evaporation can be useful to us, as you can see in the picture. You are going to work in a group to find out how people in your local area use evaporation in their daily lives. You will present your findings in a report. Step 1: Brainstorm the different ways in which we use evaporation in our lives. Step 2: Make a list of the different ways evaporation is useful to us. Step 3: Use your list to make a data sheet to find out from people in your local area the different ways in which they use evaporation. You should speak to ten people of different ages, both women and men. You can add to your list if they name other ways they use evaporation that you haven’t thought of. Here is an example of a data sheet. Do you use evaporation in any of these ways? Yes No 1 Drying washing 2 3 4 5 If possible, take some photographs to show how people use evaporation. Step 4: Use your data to draw a graph of the number of people who use evaporation in different ways. Think about the type of graph you should draw. Step 5: Use these headings and questions to write a report on your investigation. Your report should include your graphs and any photos you took. Aim: What did we want to find out? Method: What did we do to collect our data? Results: What data did we collect and how did we present it? Conclusion: What did we find out? Evaluation: How can we improve our investigation? 85  3 States and properties of matter Check your progress 1 a Does the diagram represent a model of a solid, a liquid or a gas? b Write a sentence to explain your answer. 2 a Name the three phases of water. b What is the boiling point of water? c What is the melting point of ice? 3 Write the word that describes each of the following processes: a a liquid changes into a gas at room temperature. b a gas changes into a liquid. c a solid changes into a liquid. d water changes into ice. e heated water changes into steam. 4 Sofia went into the bathroom after her big sister had a bath. It was full of mist and the mirror was covered in drops of liquid. a What was the mist made of? b What were the drops of liquid made of? c Name the process that made the drops of liquid form. d Why did the drops form? 86  Check your progress C ontinued 5 When you make jelly you mix jelly powder with water to make a solution. a Name the solute in the jelly solution. b Name the solvent in the jelly solution. c Why is the jelly solution a mixture? d What has happened to the jelly powder? e Make a drawing to show the different particles in the jelly solution. 87