Lesson 2 Matter and Its Changes

Transcription

1 Lesson 2 Matter and Its Changes Student Labs and Activities Page Launch Lab 27 Content Vocabulary 28 Lesson Outline 29 MiniLab 31 Content Practice A 32 Content Practice B 33 Language Arts Support 34 School to Home 36 Key Concept Builders 37 Enrichment 41 Challenge 42 Lab A 45 Lab B 48 Lab C 51 Chapter Key Concepts Builder Matter: Properties and Changes

2 Launch Lab LESSON 2: 10 minutes What does a change in the color of matter show? Matter has many different properties. Chemical properties can only be observed if the matter changes from one type to another. How can you tell if a chemical property has changed? Sometimes a change in the color of matter shows that its chemical properties have changed. Procedure 1. Read and complete a lab safety form. 2. Obtain the red indicator sponge and the red acid solution from your teacher. Predict what will happen if the red acid solution touches the red sponge. 3. Use a dropper to remove a few drops of acid solution from the beaker. Place the drops on the sponge. Be careful not to splash the liquid onto yourself or your clothing. 4. Record your observations in your Science Journal. Think About This 1. Compare the properties of the sponge before and after you placed the acid solution onto the sponge. Was your prediction correct? 2. Key Concept How do you know that physical properties and chemical properties changed? Matter: Properties and Changes 27

3 Content Vocabulary LESSON 2 Matter and Its Changes Directions: In this word search puzzle, find and circle the four terms listed below. Then write the correct term on the line before each definition. chemical change expose law of conservation of mass physical change E X P O S E Z L G D Y U H P T L H J Z D S D Y V G Z E C W F P A G B R O K L C S G T F A Y P G W N L X E H R T Z H B P R H T G O A H W Z V B Z O Y N U Y W C C F H Z Q Y C L I S U K S V C X K C K M C O I B O O S I L I C H N O C E W R G G G V C T Q U Y B R N N Q X E I K J A N T V F Y A K S I Z V H S Y L U A I Q W G N C E P O M A P C T G Z J Y M W X T R B V G O H Z R F O O O A Y G B V S O B A B D O N M P I Z Y D A A B Y N W Q H A X A Q S V R A X T W G B M E O P O K T K D T T L I E Q R Y Q Z S Q H X N U L V W O L E L P D S P O L K Y K G X Q N E G N A H C L A C I M E H C U O Y E J W F E A I X D L H M F U F C P R T U G B Y L W O O N V A M K M H O Z J Y E R V F L O K E A L I I N O X Y R F R W I Y Q P S G T F S S U Z E J W T X C D S S 1. total mass before and after a chemical reaction is the same 2. a change in matter in which the density of the matter stays the same 3. a change in matter in which the substances that make up the matter change into other substances with different chemical properties and physical properties 28 Matter: Properties and Changes

4 Lesson Outline LESSON 2 Matter and Its Changes A. Changes of Matter 1. Matter changes with the season, including changes in the the air. of leaves and in the 2. Matter can change in many ways, including changes and B. What are physical changes? changes. 1. In a physical change, the of the substance does not change. 2. one substance in another does not change the identities of the substances. 3. The formation of ice on the surface of a lake is an example of a(n). 4. Changes in state involve changes in the amount of that the particles in a substance have. 5. The at which one state of matter changes into another depends on how much energy is added or taken away from the substance. C. What are chemical changes? 1. In a chemical change, the substances that make up matter change into other substances with properties. physical properties and chemical 2. Changes in, density, and state of matter can be signs of a chemical change. 3. The formation of a(n) substance is the only sure sign of a chemical change. a. Formation of a(n) might be signaled by bubbles or an odor. b. Formation of a(n), a solid that sometimes forms when two liquids combine, is a sign of a chemical change. c. A change in might or might not be a sign of a chemical change. It depends on whether a(n) of forms. Matter: Properties and Changes 29

5 Lesson Outline continued 4. Energy is a sign that chemical change is involved. 5. Energy in the form of is needed for chemical reactions such as photosynthesis. 6. is a chemical reaction that only occurs if plants are exposed to light. 7. Many changes cannot be. 8. is always conserved during physical and chemical changes. 9. The law of conservation of mass states that the total mass before a(n) is the same as the total mass after it. 10. The mass of an unburned match plus the mass of the oxygen it reacts with when the match burns. D. Comparing Physical and Chemical Changes the mass of the ashes and of all the gases given off 1. Changing the shape of a piece of clay is a(n) change. 2. Spoiling foods are examples of change. 30 Matter: Properties and Changes

6 MiniLab LESSON 2: 10 minutes Is mass conserved during a chemical reaction? If you have ever seen the glow of a light stick, you have observed a chemical change. How does the chemical reaction affect the mass of the light stick? Procedure 1. Read and complete a lab safety form. 2. Obtain a light stick from your teacher. Carefully remove it from the packaging. 3. Observe the structure of the light stick. Record your observations in your Science Journal. 4. Measure and record the mass of the light stick using a balance. 5. Grasp the ends of the light stick. Gently bend it to break the inner vial. Shake the stick gently to start the reaction. 6. Use a stopwatch to time the reaction for 3 minutes. Record your observations. 7. Repeat step 4. Analyze and Conclude 1. Explain the purpose of the inner vial in the light stick. 2. Describe what occurred when the inner vial was broken. 3. Key Concept What effect did the chemical reaction have on the mass? Why? Matter: Properties and Changes 31

7 Content Practice A LESSON 2 Matter and Its Changes Directions: Complete this chart by choosing terms from the word bank and writing them in the correct spaces. boiling burning chemical changes dissolving melting photosynthesis rusting Changes to Matter Physical changes 4. examples examples Directions: Circle the term in parentheses that correctly completes each sentence. 8. When matter undergoes a physical or chemical change, the amount of mass (changes /stays the same). 9. All chemical reactions result in the production of a new substance and involve a change in (energy/volume) Some changes cannot be (repeated/reversed). 11. Photosynthesis is an example of a (physical/chemical) change that almost all living things rely on. 32 Matter: Properties and Changes

8 Content Practice B LESSON 2 Matter and Its Changes Directions: Complete each item on the lines provided. 1. What is a physical change in matter? 2. All changes in the of matter are physical changes. 3. What is a chemical change in matter? 4. Name three signs of a chemical change that are mentioned in the lesson. 5. What is the only sure sign of a chemical change? 6. What kind of energy do plants need to perform photosynthesis? 7. What happens to the total amount of mass during a physical or chemical change? Directions: Tell whether the following changes are physical (P) or chemical (C) and whether they are reversible (R) or nonreversible (N). 8. iron rusting 9. salt dissolving 10. water freezing 11. wood burning 12. pottery shattering Matter: Properties and Changes 33

9 Language Arts Support LESSON 2 Word Building Activity: Sentence Completion Directions: Study the terms and definitions below. Then write the term that correctly completes each sentence. Each term is used only once. boiling point n. temperature at which a liquid changes to a gas chemical property n. the ability or inability of a substance to combine with or change into one or more new substances density n. the mass per unit volume of a substance melting point n. temperature at which a solid changes to a liquid physical change n. any change in matter in which the identity of the matter is not changed physical property n. any characteristic of a substance that can be observed without changing the substance solubility n. the ability of one material to dissolve in another 1. The of a material is the same, despite the size or amount of the material. 2. When an ice cube melts and becomes a liquid, it undergoes a the matter. because the process does not change the composition of 3. Water turns into a gas when it is heated to 100 C because that temperature is its. 4. It takes a lot of energy to change solid steel into a liquid, because the of steel is 1,370 C. 5. One well-known of diamonds is hardness. 6. Sugar dissolves quickly in tea because it has a high in water. 7. Objects made of iron can rust, which is a of the metal. 34 Matter: Properties and Changes

10 Language Arts Support LESSON 2 Editing Activity: Simple Past Tense The simple past tense is used to write about actions and events that happened in the past. The last time Mount Shasta erupted, the damage to the surrounding areas was minor. In 1906, a severe earthquake demolished the city of San Francisco. The simple past tense is used for actions that were completed in the past and for events that took place in the past and do not continue into the present. Sometimes words in the context can be clues to use the simple past tense. The eruption of Vesuvius destroyed the Roman city of Pompeii in A.D. 79. In 2004, an undersea earthquake caused an enormous tidal wave in the Indian Ocean. For regular verbs, the past tense (verb + - ed) is formed by adding -ed to the base verb. Directions: The paragraph below should be written in the simple past tense. Circle six verb-tense errors in this paragraph and then write each corrected verb on the lines below. Many scientists work to find out how thermal energy affects the states of matter. Scientists learn that thermal energy flows from warmer places to cooler places. They discover that thermal energy depends on the movement of particles in matter. They found that matter change from one state to another when enough thermal energy was remove or add to the matter. Matter: Properties and Changes 35

11 School to Home LESSON 2 Matter and Its Changes Did you know? Many foods you eat require chemical reactions to reach their final form. Have you ever noticed that in many baked goods, such as brownies, cookies, or cakes, the finished product is different from the ingredients used to make it? The difference is the result of a chemical reaction that has taken place at some point during the preparation of the food. Mixing the ingredients or applying heat to the ingredients, or both, can cause the chemical reaction. Directions: Work with your learning partner to complete the activity and answer each question. 1. Observe an egg as it is cooked by your adult learning partner. You can observe an egg being fried, hard boiled, or cooked in any other way. How is the raw form of the egg different from its cooked form? 2. How do you know that a chemical reaction has occurred when the egg was cooked? 3. Chemical changes are one kind of change matter can undergo. Matter can also undergo physical changes. What are two physical changes the egg could undergo? 4. How are physical changes different from chemical changes? 36 Matter: Properties and Changes

12 Key Concept Builder LESSON 2 Matter and Its Changes Key Concept How are physical changes different from chemical changes? Directions: On the line before each change, write P for physical or C for chemical. 1. glass melting 2. wood burning 3. bread baking 4. water vapor condensing 5. iron rusting 6. leaves changing color 7. sugar dissolving 8. oxygen becoming liquid 9. silver tarnishing Directions: Some changes can be reversed others cannot. Put a check mark on the line before each change that is reversible. Put an X on the line before each change that is not reversible. 10. making water into ice 11. hard-boiling an egg 12. dissolving salt in water 13. breaking a window 14. scorching a fabric Matter: Properties and Changes 37

13 Key Concept Builder LESSON 2 Matter and Its Changes Key Concept How are physical changes different from chemical changes? Directions: Complete these diagrams by choosing terms from the word bank and writing them in the correct spaces. burns evaporates heat ice light spark sunlight vapor water wood Physical Chemical ignites melts which into producing which later and to become a Directions: Complete each item below. 11. Put a star next to the words above that are sources of energy or the release of energy. 12. Ice must absorb heat to melt into water. What must water do to evaporate? 38 Matter: Properties and Changes

14 Key Concept Builder LESSON 2 Matter and Its Changes Key Concept How are physical changes different from chemical changes? Many signs indicate that substances have undergone a chemical change rather than a physical change. These signs show that a new substance has been formed from a chemical reaction. Three signs of a chemical change are changes in color, the release of a gas, and the formation of a new solid substance, such as a precipitate. Directions: Work with a partner. Tell which signs of a chemical change occur with each of the processes below. 1. a log burning 2. photosynthesis 3. oxidation of silver Directions: Complete each item below with your partner. 4. Another name for a chemical change is a(n). 5. Respiration is a chemical change that occurs inside your body. What gas do you release every time you exhale? Matter: Properties and Changes 39

15 Key Concept Builder LESSON 2 Matter and Its Changes Key Concept How do physical and chemical changes affect mass? Directions: Complete each item below on the lines provided. 1. The principle that mass is never lost in physical and chemical changes is known as the law of. 2. The ashes left by a forest fire don t weigh as much as the trees did. Knowing that mass is never destroyed, explain what happened to some of the mass of the trees as they burned. 3. When water freezes, it expands in volume by 10 percent. If you froze 200 g of water, what would be the mass of the resulting block of ice? Explain your answer. 4. What happens to the mass of a soft drink when you open it? 5. If you could put a sealed room on a very sensitive scale and open a thousand soft drink cans inside it, would the mass reading on the scale go up, go down, or stay the same? Explain your answer. 40 Matter: Properties and Changes

16 Enrichment LESSON 2 Particles, Odor, and Smell Some types of solid matter are volatile, meaning that particles evaporate from it. Any matter that has an odor is giving off particles into the air. Smell is the process of perceiving that odor. A unique odor can trigger distinct memories from the past or from emotional moments, but the mechanism for that trigger has not yet been explained. The sense of smell, called olfaction, is considered by scientists to be the most mysterious of our senses. In humans, a special patch of nerve cells about the size of a postage stamp is located at the top of the nasal passage, behind the nose. These nerve cells are called olfactory receptor cells. They are out in the open where they can come into contact with the air. The cells have hairlike projections called cilia that increase their surface area. When you breathe in an odor particle from a piece of matter, it binds to the cilia of the receptor cells in the nose. One scientific theory is that the smell signal is not triggered by an odor particle s shape but by its vibrations. The diagram shows how the particles (odorant molecules) of matter enter the nose and react with the receptor cells. Odorant Receptors and the Organization of the Olfactory System Olfactory bulb 4. The signals are transmitted to higher regions in the brain. Bone Nasal epithelium Olfactory receptor cells 1. Odorants bind to receptors Air with odorant molecules Applying Critical-Thinking Skills Directions: Respond to each statement. 3. The signals are relayed in glomenulus. 2. Olfactory receptor cells are activated and send electric signals. 1. Explain why particles from a piece of matter can diffuse into the air. 2. Deduce why cold bacon smells very little, but frying bacon can be smelled from another room. Matter: Properties and Changes 41

17 Challenge LESSON 2 Using Odor to Identify Matter Design an experiment to find out how far away from the source someone can be and still smell particles from different kinds of matter. Good subject matter might be scented candles, different foods, paint, and spices. Consider the following in your design: Select at least six different kinds of matter. What will you use as a control? How many trials will you run? Choose the number of subjects. Use this format to write about your experiment. Question Materials Method Data Collection Data Analysis Conclusion New Questions for Further Study 42 Matter: Properties and Changes

18 Lab A 40 minutes Identifying Unknown Minerals Imagine you are a geologist digging for minerals. You find one that you would like to identify. What properties of the mineral would help you? Geologists consider many physical properties of a mineral when they determine its identification. Question How can you use physical properties to identify unknown minerals? Materials mineral samples 100-mL graduated cylinder Safety Procedure nail triple-beam balance 1. Read and complete the lab safety form. 2. Select a mineral sample to observe. Record its color. 3. Observe the hardness of your mineral. a. Scratch your mineral with your fingernail. If it scratches, then your mineral has a low hardness. Go to step 4. If it does not scratch, go to step 3b. b. Scratch your mineral with a nail. If it scratches, it has a moderate hardness. If it does not scratch, it has a high hardness. Write whether your mineral has a low hardness, moderate hardness, or high hardness. 4. Compare the properties of your mineral with the properties in the chart. Is there a mineral on the chart that has similar color and hardness to yours? If there is, write that mineral, its color, and its hardness. 5. Think about the properties you observed so far. Can you tell which mineral you have based on your initial observations? Explain why or why not below. Matter: Properties and Changes 45

19 Lab A continued Physical Properties of Minerals Mineral Color Typical Density (g/cm 3 ) Hardness Fluorite white or light green 3.1 moderate Gypsum white or brown 2.3 fairly soft Hornblende black or grayish brown 3.2 moderate Magnetite (iron ore) dark gray 5.2 moderate Quartz white or colorless 2.6 fairly hard Sphalerite (zinc ore) black or reddish brown 4.1 fairly soft 6. Look back through the chapter to review the physical property density. 7. Design an experiment using mass and volume to determine the density of your mineral. Write your procedure. Hint: Use the table to help. Mass Volume 8. Share your procedure with your teacher for approval before conducting your experiment. Perform your experiment and record the mass and volume of your mineral in the table. What is the density of your mineral? 46 Matter: Properties and Changes

20 Lab A continued 9. Compare your results with information in the Physical Properties of Minerals table. Lab Tips Put your eye at the level of the liquid. Observe the level at the center or bottom of the curve in the surface of the liquid (called the meniscus). When measuring, remember that 1 ml = 1 cm 3. Analyze and Conclude 10. Infer the identity of your mineral sample. 11. The Big Idea Which physical property was most useful in identifying the mineral? Why? Remember to use scientific methods. Make Observations Ask a Question Form a Hypothesis Test your Hypothesis Analyze and Conclude Communicate Results 12. Predict Suppose you have another sample of the same mineral. What properties would you expect to be the same? What properties would be different? Communicate Your Results In a small group, share your experiences and your results. How did you collect and record data? What was successful? Did others use different techniques or get different results? Did anything surprise you? Matter: Properties and Changes 47

21 Lab B 40 minutes Identifying Unknown Minerals Imagine you are a geologist digging for minerals. You find one that you would like to identify. What properties of the mineral would help you? Geologists consider many physical properties of a mineral when they determine its identification. Question How can you use physical properties to identify unknown minerals? Materials mineral samples 100-mL graduated cylinder nail triple-beam balance Safety Procedure 1. Read and complete the lab safety form. 2. Select a mineral sample to observe. Record its color. 3. Observe the hardness of your mineral. a. Scratch your mineral with your fingernail. If it scratches, then your mineral has a low hardness. Go to step 4. If it does not scratch, go to step 3b. b. Scratch your mineral with a nail. If it scratches, it has a moderate hardness. If it does not scratch, it has a high hardness. 4. Compare the properties of your mineral with the properties in the chart. Mineral Physical Properties of Minerals Color Typical Density (g/cm 3 ) Hardness Fluorite white or light green 3.1 moderate Gypsum white or brown 2.3 fairly soft Hornblende black or grayish brown 3.2 moderate Magnetite (iron ore) dark gray 5.2 moderate Quartz white or colorless 2.6 fairly hard Sphalerite (zinc ore) black or reddish brown 4.1 fairly soft 48 Matter: Properties and Changes

22 Lab B continued 5. Think about the properties you observed so far. Are you able to determine which mineral you have based on your initial observations? Explain why or why not below. 6. Look back through the chapter to review the physical property density. 7. Design an experiment using mass and volume to determine the density of your mineral. Write your procedure here. 8. Share your procedure with your teacher for approval before conducting your experiment. 9. Compare your results with information in the Physical Properties of Minerals table. Lab Tips To measure the water in a cylinder accurately, first put your eye at the level of the liquid. Then observe the level at the meniscus (the center or bottom of the curve in the surface of the liquid). 1 ml = 1 cm 3 Analyze and Conclude 10. Infer the identity of your mineral sample. Matter: Properties and Changes 49

23 Lab B continued 11. The Big Idea Which physical property was most useful in identifying the mineral? Why? Remember to use scientific methods. Make Observations Ask a Question 12. Predict Suppose you have another sample of the same mineral. What properties would you expect to be the same? What properties would be different? Form a Hypothesis Test your Hypothesis Analyze and Conclude Communicate Results Communicate Your Results In a small group, share your experiences and your results. How did you collect and record data? What was successful? Did others use different techniques or get different results? Did anything surprise you? Extension Choose a different unknown sample to test that looks similar to the one you tested. Which properties might be different? Test your sample in the same way you tested the first one. Were the results the same or different? What can you conclude from this? 50 Matter: Properties and Changes

24 Lab C 45 minutes Testing Mineral Samples Directions: Use the information and data from the Lab Identifying Unknown Minerals to perform this lab. Choose a different unknown sample to test. Based on what you have learned already, predict which properties might be different. Test your sample in the same way you tested the first one. What can you conclude? Please note that you must complete Lab B before completing Lab C. Have your teacher approve your design and safety precautions before beginning your experiment. Matter: Properties and Changes 51

25 Chapter Key Concepts Builder Matter: Properties and Changes End-of-Chapter Practice Directions: Form small groups. Take turns presenting questions to the group. Call on members of your group to discuss the answers. Write the answers that your group has settled on. Then compare your answers with those of other groups. 1. What two kinds of properties give a substance its unique identity, and what are some examples of each? 2. If a given amount of mass remains the same but its density increases, what happens to its volume? 3. What happens to the attractive forces between particles of water as they turn into steam? 4. If an object has a mass of 10 kg on Earth, what would be its mass on a planet with half the gravity of Earth? Explain your answer. 5. Suppose someone gave you an old car with a badly rusted body. Is there anything you could do to return the car s original metalwork to like-new condition? Explain your answer. 52 Matter: Properties and Changes