CHAPTER 10 Changes in Matter Lesson 1

Changes of State. . .

396

Lesson 2

Physical Changes . .

406

Lesson 3

Chemical Changes. . 4 1 6

In what ways can matter change?

394

Key Vocabulary melt to change from a solid to a liquid (p. 398)

More Vocabulary evaporate, p. 399 condense, p. 400 freeze, p. 401

boil to change from a liquid to a gas (p. 399)

physical change a change in the way matter looks (p. 408)

mixture different kinds of matter mixed together (p. 410)

solution when one or more kinds of matter are mixed evenly into another kind of matter; a solution can be a solid, a liquid, or a gas (p. 411) chemical change a change that causes different kinds of matter to form (p. 418)

395

Lesson 1

Changes of State

A winter storm can bring snow and ice. What happens to snow on a warm, sunny day? What causes this change?

396

ENGAGE

What happens when ice is heated?

Materials

Make a Prediction How does ice change as it is heated? Write a prediction. thermometer

Test Your Prediction Measure Place a thermometer in a cup of ice. Measure the temperature of the ice. Record the temperature in a table like the one shown.

plastic cup of ice

Place the cup in a warm place, such as on a sunny windowsill.

Measure Stir the ice and measure its temperature every 10 minutes for the next hour. Record the temperature in the table. Describe how the ice changes.

Draw Conclusions

spoon Step

Time

Temperature

Communicate How did the ice change as it was heated? Was your prediction correct?

Infer What happened to the temperature of the water as the ice melted? At what temperature does ice melt?

Explore More

Step

Predict What will happen to the water as it continues to sit in the warm place after the ice has melted? Test your prediction and find out.

397

EXPLORE


Main Idea Adding or removing heat can cause matter to change state.


Vocabulary melt, p. 398 boil, p. 399 evaporate, p. 399 condense, p. 400 freeze, p. 401

-Glossary at

www.macmillanmh.com


Reading Skill Predict  

   




What happens when matter is heated? When matter is heated, it gains energy. Its temperature rises. At certain temperatures, matter will change state.

Changing from a Solid to a Liquid If you heat most solids to a high enough temperature, they will melt. To melt is to change from a solid to a liquid. Different kinds of matter melt at different temperatures. Ice melts at a lower temperature than rocks. Ice melts at 32˚F (0˚C). Rocks melt at over 1,100˚F (593˚C)! Remember that all matter is made up of tiny particles. In solids these particles are held closely together. When a solid is heated and gains energy, its particles begin to move away from each other. They flow around each other and are no longer held tightly together. This causes the solid to lose its shape. It becomes a liquid.


Technology Explore how matter changes with the Secret Agents.

The lava flowing from this volcano is rock that melted deep beneath Earth’s surface.

398

EXPLAIN

Changing from a Liquid to a Gas If you heat a liquid to a high enough temperature, it will boil. To boil is to change from a liquid to a gas. Energy from heat causes the particles in a liquid to move faster. They spread apart. The liquid turns into a gas.


These clothes will dry when the liquid water changes into a gas.

Liquids can also evaporate, or change into a gas, slowly. When wet clothes are placed in the Sun, the water in the clothes evaporates. The Sun heats water droplets in the clothes. The water turns into a gas and your clothes dry. The gas state of water is called water vapor. You cannot see water vapor, but it is part of the air. Heating Water

solid

liquid

gas

Read a Diagram What happens when you heat ice?

Quick Check

Clue: Arrows show a sequence.

Predict What will happen

to cheese when it is heated? Watch how matter changes at www.macmillanmh.com

Critical Thinking How does

a blow dryer get your hair dry? 399

EXPLAIN

What happens when matter is cooled? When matter is cooled, it loses energy. Its temperature drops. At certain temperatures, matter will change state.

Changing from a Gas to a Liquid If you cool a gas to the right temperature, it will condense (kuhn•DENS). To condense is to change from a gas to a liquid. For example, on cool mornings, small droplets of water called dew can appear on grass and windows. This happens when water vapor in the air touches cool objects and loses energy. Particles of water vapor come closer together. They change into drops of liquid water.

Dew forms when water vapor in the air cools and condenses.

Water vapor in this tiger’s breath condenses on a cold day.

400

EXPLAIN

Changing from a Liquid to a Solid If you cool a liquid to the right temperature, it will freeze. To freeze is to change from a liquid to a solid. The particles in the liquid lose energy and move slower and closer together. They get locked into position and form a solid. For example, when you put liquid water into the freezer, it loses energy. It cools to a certain temperature and turns into ice.

Condense Water Vapor Observe Feel an empty plastic cup. Does it feel wet or dry? Does it feel hot or cold? Record your observations. Fill your cup with ice cubes. Next add cold water to the cup. Observe Feel your cup again. Does the cup feel wet or dry? Does the cup feel hot or cold? Record your observations. Observe Look at your cup after five minutes. What do you notice about the outside of the cup? Is it wet or dry? Infer Where did the water on the cup come from?


When juice is cooled enough, it will freeze and become a solid.

Quick Check Predict What will happen to

water vapor when it is cooled? Critical Thinking How could

you make an ice pop? 401

EXPLAIN

How is water different from other kinds of matter? Most kinds of matter shrink as they freeze. Their particles get packed more closely together. They take up less space. Yet water gets larger when it freezes. As water freezes, its particles rearrange themselves. They make a special pattern. Empty spaces form between the particles. The frozen water takes up more space than the liquid water. This is why freezing a glass of water cracks the glass. Ice floats in liquid water. This keeps lakes and ponds from freezing from the bottom up. Living things can survive under the ice. Quick Check Predict What would happen if you put

a plastic bottle filled with liquid water in the freezer? Why does this happen? Critical Thinking Describe how water

changes when it melts. The particles in ice are more spread out than the particles in liquid water. This is why ice floats. solid water liquid water

402

EXPLAIN

Ice, liquid water, and water vapor are all forms of water.

Visual Summary When most solids are heated, they melt into liquids. When a liquid is heated, it changes into a gas. When a gas cools it usually condenses into a liquid. When a liquid cools it freezes into a solid.

Think, Talk, and Write Main Idea How can heat change matter?

Vocabulary What happens when a gas condenses?

Predict After a rainstorm the Sun comes out and shines brightly. What will happen to puddles of rainwater?  

   




Water is a special kind of matter. It gets larger when it freezes.

Critical Thinking You see drops of water on the bathroom mirror after a shower. What caused the water drops to form?

Make a Study Guide Make a LayeredLook Book. Use it to summarize what you learned about changes of state.

Writing Link Write a Story Describe how your life would be different if liquids changed into solids when heated. For example, it could snow when the temperature outside was very hot.

Test Prep How is water different from other liquids? A Water gets larger as it freezes. B Water gets smaller as it freezes. C Water stays the same as it freezes. D Water never freezes.

Math Link Find the Difference Ice melts at 32°F. Water boils at 212°F. How many degrees are there between water’s melting and boiling temperatures?

-Review Summaries and quizzes online at www.macmillanmh.com

403

EVALUATE

Inquiry Skill:

Predict

You just learned about how liquids change to solids. Which do you think freezes faster, salt water or fresh water? To find answers to questions like this, scientists first predict what they think will happen. Next, they experiment to find out what does happen. Then, they compare their results with their prediction.


Learn It When you predict, you state the possible results of an event or experiment. It is important to record your prediction before you do an experiment. Next, you record your observations as you experiment and record the final results. Then you have enough data to figure out if your prediction was correct.

Ice floats on the salt water of Shoup Bay in Alaska.

404

EXTEND


Try It Which do you think freezes faster, salt water or fresh water? Predict what will happen when you freeze fresh water and salt water. Write your prediction on a chart like the one shown. Then do an experiment to test your prediction. Materials measuring cup, water, two

plastic cups, salt, measuring spoon

Which Freezes Faster? My Predictions Observations of fresh water

Pour 125 mL of water into a plastic cup. Label this cup Fresh Water.

Observations of salt water

Pour 125 mL of water into another plastic cup. Add 1 tablespoon of salt and stir with a spoon. Label this cup Salt Water.

Results

Place both cups into the freezer. Check them every 15 minutes. Draw or write your observations. Now answer these questions. Which freezes faster, fresh water or salt water? Was your prediction correct?


Apply It Now that you have learned to think like a scientist, make another prediction. Do you predict that salt water or fresh water will evaporate faster? Plan an experiment to find out if your prediction is correct.

405

EXTEND

Lesson 2

Physical Changes

Changes take place around you all the time. This clay is changing shape. What objects around you change every day? How do they change?

406

ENGAGE

How can you change matter?

Materials

Purpose Find out some ways you can change matter.

Procedure Make a table like the one shown below.

Object

Change

paper

Properties changed

Paper Clay

clay

Ice cubes ice cubes

Observe Look at each object. What properties does each object have? How can you change each object? Record your plan.

scissors

Experiment Change each object. What properties does each have now? Record the property that has changed. Be Careful. Handle scissors carefully.

Step

Draw Conclusions How are the objects different after you made the changes?

Infer Do you think you changed the kind of matter making up the object? Explain.

Explore More Experiment What would happen if you added a spoon of salt to a cup of water? How would the salt and water change? How could you remove the salt from the water?

407

EXPLORE

What are physical changes? 
Main Idea Matter looks different after a physical change, but it is still the same kind of matter. You can mix matter together to form mixtures and solutions.


Vocabulary physical change, p. 408 mixture, p. 410 solution, p. 411

-Glossary at

www.macmillanmh.com


Reading Skill Draw Conclusions  
 

Matter can change. A physical change (FIZ•i•kuhl CHAYNJ) is a change in the way matter looks. Tearing a sheet of paper is a physical change. The size and shape of the paper are different, but the paper is still paper. Matter looks different after a physical change, but it is still made of the same kind of matter. A change of state is also a physical change. When liquid water freezes, its state changes from a liquid to a solid. The water looks different, but it is still water. Not all types of matter change in the same way. If you pull on a rubber band it stretches. When you let go, it returns to its original size. If you pull on a metal spoon, nothing happens. If you pull on a piece of thread, it might break.

   

Painting an object does not change what the object is made of. 

408

EXPLAIN

How Steel Changes Solid steel is melted into a liquid. The melted steel can be shaped to make the frame of a car.


The steel hardens. Now it is a solid. It is combined with other materials to make a car.

The steel is now part of a car. The car is ready to drive on the highway.

In time, the car is crushed. The steel can be melted and used again to make other steel products.

Read a Chart What physical changes have happened to the steel? Clue: Look at how the steel has changed in each photograph. Use the captions to help.

Quick Check Draw Conclusions Why is a change of state

a physical change? Critical Thinking Make a list of three physical

changes you could make to a piece of paper. 409

EXPLAIN

What happens when you mix matter? Another kind of physical change is a mixture (MIKS•chuhr). A mixture is different kinds of matter mixed together. When you pour milk on your cereal, you are making a mixture. In a mixture the properties of each kind of matter do not change. The milk is still milk, and the cereal is still cereal. A mixture can be a combination of solids, liquids, and gases. Vegetable soup is a mixture of liquids and solids. Salad dressing can be a mixture of different liquids. Clouds are a mixture of air, dust, and water droplets.

410

EXPLAIN

Solutions can be solid.


What makes up this mixture?

Solutions There are many kinds of mixtures. One kind of mixture is a solution (suh•LEW•shuhn). A solution forms when one or more kinds of matter are mixed evenly into another kind of matter. Salt water is a solution. If you add salt to water, the salt mixes evenly with the water. You cannot see the salt, but it is still there. If the water evaporates, the salt will be left behind. Not all solids form solutions in liquids. Try to mix sand with water. The sand will just sink to the bottom. Some things will not form solutions no matter how long you stir. Some solutions contain no liquids at all. Air is a solution of different gases. Brass is a solution of several solids, including copper and zinc.

Brass is a solution of metals. It is used to make musical instruments.

Quick Check Draw Conclusions Do all kinds of Ocean water is a mixture. It contains many different types of matter, including salt, water, and oxygen.

matter form solutions with water? Explain your answer. Critical Thinking You cannot see

that salt is in salt water. How do you know it is there? 411

EXPLAIN

Separating Mixtures Mix some sand, marbles, and paper clips together in a bowl.

Experiment Design an experiment to separate this mixture. Observe Were you able to completely separate the mixture? How do you know? Experiment How could you separate a mixture of sugar and water?

How can mixtures be separated? Some properties help you separate mixtures. These properties include size, shape, and color. One way to separate a mixture is to pick out each different type of matter. In a mixture of spaghetti and meatballs, you can pick out the meatballs. Another way to separate a mixture is by evaporation. Leave a solution of salt and water in a warm place. As the water evaporates, the salt is left behind. The photos below show some other ways to separate mixtures. Quick Check Draw Conclusions How can

you separate peas from carrots? Critical Thinking List some

ways to separate sand from salt. Objects that float, such as these cranberries, can be separated from objects that sink. 

412

EXPLAIN

Filters separate mixtures by size. 

Magnets separate certain metals from other objects. 

Visual Summary

Think, Talk, and Write

Physical changes cause matter to look different. The kind of matter stays the same.

Main Idea Describe and explain

A mixture is a combination of two or more types of matter.

Draw Conclusions A sculptor carves a statue out of a rock. Is this a physical change? How do you know?

three types of physical changes.

Vocabulary What is a mixture?

 
 

   

Some properties can help you separate a mixture.

Critical Thinking How could you separate plastic paper clips from metal paper clips?

Make a Study Guide

Test Prep Noodles and broth could

Make a Trifold Book. Use it to summarize what you learned about physical changes.

Math Link Sort and Classify Materials What materials dissolve in water? Try mixing several materials, such as salt, flour, sugar, soil, and cooking oil, with water. Then classify the materials into groups to show which dissolve and which do not. Make a chart to show your results.

be separated by A heating in an oven. B boiling in a pot. C filtering. D freezing.

Art Link Experiment with Color Cut a circle out of a coffee filter. Use a black marker to draw a spot in the center of the filter. Put the filter on a plate. Add a few drops of water to the spot. Watch what happens. Why do you think this happens? What does this tell you about ink?

-Review Summaries and quizzes online at www.macmillanmh.com

413

EVALUATE

Did you use something made of metal today? You might have if you ate breakfast with a spoon or rode your bike to school. Both are made of metals. Metals come from the earth. Metals are found in ores. Ores are rocks that have useful minerals. Some of these minerals contain metals, such as silver or copper. Ores can be found in all kinds of places, from volcanoes to river valleys to mountains. An ore is usually mined from the ground. Then it is crushed into powder. Magnets, oil, chemicals, and streams of water can be used to separate the minerals from the powdered rock. Later, these minerals are heated to high temperatures to draw out the metals inside them. Once separated, the metals can be mixed with other metals. Then the metals are used to create products, such as the spoon or bicycle you used today.

414

EXTEND

Science, Technology, and Society

rock crusher

Infer When you infer  you use what you already know  you use facts in the article  you form new ideas

Write About It Infer Read the article with a partner. Use what you know and what you read in the article to answer this question. Why do you think it is important for people to recycle metals? Write a paragraph to share your ideas.

-Journal Write about it online at www.macmillanmh.com

415

EXTEND

Lesson 3

Chemical Changes

Have you ever baked a cake? Why doesn’t a cake taste like the ingredients it is made from? What happens to the ingredients to make them taste different?

416

ENGAGE

How can matter change?

Materials

Make a Prediction How do flour and baking soda change when each is mixed with vinegar? Write a prediction.

Test Your Prediction

vinegar

flour

Be Careful. Wear goggles.

baking soda

Observe List the properties of the vinegar, flour, and baking soda.

Measure Use a funnel to put 2 tablespoons of flour in one balloon. Add 50 mL of vinegar to a plastic bottle.

goggles

funnel

Experiment Carefully, put the balloon over the bottle’s opening without letting any flour fall into the bottle. After you attach the balloon, raise it up so the flour goes into the bottle. Record your observations.

measuring cup and spoons

Repeat steps 2 and 3 using the second balloon and baking soda instead of flour.

Draw Conclusions

2 balloons

Did your results match your prediction? Explain your answer.

Infer What do you think caused the differences in the balloons?

2 plastic bottles

Step

Explore More Experiment What might happen to the balloon if you add two tablespoons of baking soda and 50 mL of water to a container? Try it and find out.

417

EXPLORE

What are chemical changes? 
Main Idea Chemical changes cause different kinds of matter to form.


Vocabulary chemical change, p. 418

-Glossary at

www.macmillanmh.com


Reading Skill Infer  
  

 

 
 

You may have seen an apple turn brown or a burning log change into ash and smoke. Both are examples of a chemical change (KEM•i•kuhl CHAYNJ). A chemical change is a change that causes different kinds of matter to form. The properties of the new matter are different from those of the original materials. Chemical changes happen every day. Your body uses chemical changes to break down the food you eat. Green plants use the Sun’s energy to change carbon dioxide and water into food and oxygen. Cooking also uses chemical changes. Cake batter changes when you bake it. You know that it has changed because it feels and tastes different.

A Chemical Change unripe

ripe

overripe

A chemical change happens when fruit ripens. As bananas ripen, they change color. They also become softer and sweeter.

Read a Diagram How have the bananas in these photographs changed? Clue: Compare the three photographs to find differences.

418

EXPLAIN

Not all chemical changes are useful. A car made out of iron may rust. Rust is very different from iron. It is weaker and it peels. Food spoils as a result of chemical changes. Materials in food can break down and form new materials. When this happens food may change color or smell bad. Quick Check Infer Is it a physical or chemical

change when milk spoils? Why? Critical Thinking Why are

chemical changes important to living things?

A Chemical Change Observe Look closely at some pennies. Make a list of their properties. Place 1 teaspoon of salt in a bowl. Add 150 mL of vinegar. Stir until the salt dissolves. Experiment Dip a penny halfway into the liquid. Slowly count to 20 as you hold the coin there. Then remove the penny. Compare the half you held with the half that was in the liquid. Infer What caused the change in appearance?

Water and oxygen caused the iron in this train to rust. 

419

EXPLAIN

What are the signs of a chemical change? Sometimes a chemical change happens when different materials are put together. Certain signs can show that a chemical change has happened. Here are a few.

Light and Heat A burning log changes into carbon dioxide gas and ash. As the log burns, it releases light and heat. The light and heat are signs of a chemical change.


Heat and light are two signs of a chemical change.

Formation of Gas The formation of a gas can be a sign of a chemical change. When you add baking soda to vinegar, carbon dioxide gas forms. As this gas escapes from the liquid, bubbles form.

Color Change Sometimes a color change shows that a chemical change has happened. The Statue of Liberty used to be the same color as a penny. It turned green as a result of a chemical change. Quick Check Infer Is a burning match a

physical or chemical change? How do you know? Critical Thinking Is sugar

dissolving in water a physical or chemical change? Explain. 420

EXPLAIN


These bubbles tell you a chemical change is occurring.

The Statue of Liberty got its green color from a chemical change. 

Visual Summary Chemical changes cause different kinds of matter to form.

Think, Talk, and Write Main Idea List three things that may tell you a chemical change has occurred.

Vocabulary What is a chemical You observe chemical changes every day.

change? Give an example.

Infer Two clear liquids are combined. Bubbles form. What kind of change might have happened? Explain. Light and heat, formation of a gas, and a color change are signs of a chemical change.

 

 
  

 
 

Critical Thinking Mrs. Hall wiped a discolored pot with a special cleaner. The pot returned to its original color. What happened?

Make a Study Guide Make a Trifold Book. Use it to summarize what you learned about chemical changes.

Test Prep Which is a chemical change to a piece of paper? A folding B cutting C tearing D burning

Math Link Solve a Problem A log takes one hour to burn down to ash. A banana turns brown and mushy in four days. How many hours did the longer chemical change take?

Social Studies Link Conduct Research Bread is made differently in other countries. Different ingredients make different chemical changes. Research how bread is made in other countries.

-Review Summaries and quizzes online at www.macmillanmh.com

421

EVALUATE

Materials

chalk

Structured Inquiry

How can physical and chemical changes affect matter? Form a Hypothesis

hand lens

How will breaking chalk change the chalk? How will adding vinegar to the chalk change it? Write a hypothesis.

Test Your Hypothesis

black construction paper

Observe Break a piece of chalk in half. Use a hand lens to look at the broken end of the chalk. Record your observations. Is this a chemical or physical change? Experiment Rub one

vinegar

Step

of the chalk pieces on a piece of black paper. Using the hand lens look at the chalk on the paper. Record your observations. Is this a chemical or physical change?

Experiment Use a dropper to add

dropper

one drop of vinegar to the chalk on the black paper. Record your observations. Is this a chemical or physical change?

Draw Conclusions Interpret Data What did you observe? Which changes were physical changes? Was there a chemical change?

Step

422

EXTEND

Infer Describe what happened to the chalk when you added the vinegar. What caused this to happen?

Communicate Use your observations to write your own definitions of chemical and physical change.

Guided Inquiry

Open Inquiry

What are the signs of a chemical change? Form a Hypothesis How can you tell a chemical change has happened? Write a hypothesis.

What else would you like to know about physical and chemical changes? Come up with a question to investigate. For example, how does iron rust? Design an experiment to answer your question.

Test Your Hypothesis Design an experiment to investigate chemical changes. Use the materials shown. Write the steps you plan to follow. Record your results and observations.

Remember to follow the steps of the scientific process. Ask a Question

Materials Form a Hypothesis

plastic cups

spoon

milk

Test Your Hypothesis

Draw Conclusions

iron wool

vinegar

baking soda

Draw Conclusions What changes did you observe? Did your experiment support your hypothesis? Why or why not?

423

EXTEND

CHAPTER 10 Review Visual Summary

Fill each blank with the best term from the list.

Lesson 1 Adding or removing heat can cause matter to change state.

chemical change, p. 418

Lesson 2 Matter looks different after a physical change, but it is still the same kind of matter.

freeze, p. 401

Lesson 3 Chemical changes cause different kinds of matter to form.

condense, p. 400 evaporate, p. 399

mixture, p. 410 melt, p. 398 physical change, p. 408 solution, p. 411

1. When you mix spaghetti and meatballs together, you make a .

Make a Study Guide

2. Tearing a sheet of paper is a .

Glue your lesson study guides to a piece of paper as shown. Use your study guide to review what you have learned in this chapter.

3. If you a solid.

a liquid, it becomes

4. A change that causes different kinds of matter to form is a . 5. To change from a liquid to a gas slowly is to . 6. When you mix salt with water you make a . 7. To change from a solid to a liquid is to . 8. If you cool a gas to the right temperature, it will , or turn into a liquid.

424

-Review Summaries and quizzes online at www.macmillanmh.com

Answer each of the following in complete sentences. 9. Infer What kind of change occurs when you toast bread? What kind of change occurs when butter melts on a piece of toast? Explain your answer. 10. Expository Writing Describe what happens to water as it freezes.

Act It Out! 
With a partner, act out one important term or idea from this chapter. For example, you may choose a term such as melt. You may not speak during your skit. 
Present your skit to the class. Then let other students guess the term. 
What information about your term or idea did you show? How did you show it?

11. Predict It is a warm, sunny day. You leave a bar of chocolate on the 
What details helped you guess other window sill. How do you think it will pairs’ terms and ideas? change? Can you change it back? 12. Critical Thinking You add sugar to a glass of lemonade and stir it. You cannot see the sugar anymore. The lemonade tastes sweet now. What kind of mixture is this? How do you know? 13. Study the photograph. In what two states of matter is water shown? Describe how they are different. 1. Which of the following BEST describes what happens when a log burns? A A chemical change is taking place. B The logs are becoming a liquid. C The logs are getting bigger. D Smoke is boiling.

14. In what ways can matter change?

425

Environmental Chemist Do you like helping keep plants and animals healthy? Are you concerned with keeping the environment clean? If so, then you might like to be an environmental chemist. An environmental chemist is a kind of scientist. These scientists help keep the water, land, and air free of pollution. Pollution can hurt plants, animals, and people. Environmental chemists protect living things by helping clean up pollution. Environmental chemists also show people how to reduce pollution. To become an environmental chemist, you should begin learning about the environment where you live. Start a recycling program in your home or at school to reduce waste. You could also join a group that helps protect the environment.

 This scientist is collecting data on water pollution.

Here are some other Physical Science careers: • carpenter • lab technician • chemical engineer • pharmacist

426


This chemist is testing to see how much oil is left on a beach after a spill.

-Careers at www.macmillanmh.com