Lesson 2 Changes in State

Transcription

1 Lesson 2 Changes in State Student Labs and Activities Page Launch Lab 25 Content Vocabulary 26 Lesson Outline 27 MiniLab 29 Content Practice A 30 Content Practice B 31 Language Arts Support 32 School to Home 34 Key Concept Builders 35 Enrichment 39 Challenge 40 Skill Practice States of Matter

2 Launch Lab LESSON 2: 10 minutes Do liquid particles move? If you look at a glass of milk sitting on a table, it appears to have no motion. But appearances can be deceiving! Procedure 1. Read and complete a lab safety form. 2. Use a dropper, and place one drop of 2 percent milk on a glass slide. Add a cover slip. 3. Place the slide on a microscope stage, and focus on low power. Focus on a single globule of fat in the milk. Observe the motion of the globule for several minutes. Record your observations in the Data and Observations section below. Data and Observations Think About This 1. Describe the motion of the fat globule. 2. What do you think caused the motion of the globule? 3. Key Concept What do you think would happen to the motion of the fat globule if you warmed the milk? Explain. States of Matter 25

3 Content Vocabulary LESSON 2 Changes in State Directions: Each of the sentences below is false. Make the sentence true by replacing the underlined word(s) with a term from the list below. Write your changes on the lines provided. condensation deposition evaporation kinetic energy sublimation temperature thermal energy vaporization 1. The process of thermal energy is the opposite of the process of evaporation. 2. The average kinetic energy of the particles in a substance is measured by the substance s condensation. 3. It rained yesterday; however, due to vaporization, the puddles are all gone today. 4. The gaseous state of a given substance has greater deposition than the liquid or solid states because the particles of the substance are moving more in the gaseous state than in the other states. 5. The process of thermal energy is the opposite of the process of deposition. 6. Kinetic energy is different from temperature because it includes the total potential energy and kinetic energy of an object. 7. Temperature results in matter changing from a gas directly to a solid, without going through the liquid state. 8. Evaporation and boiling result in sublimation of a liquid. 26 States of Matter

4 Lesson Outline LESSON 2 Changes in State A. Kinetic and Potential Energy 1. All objects in motion have energy, which is energy due to its. 2. Within a given substance, particles in the substance s state have the least amount of kinetic energy and particles in the state have the most kinetic energy. 3. is the measure of the average kinetic energy of all the particles in an object. 4. A temperature increase within a given substance a means that the particles, on average, are moving at have speeds and kinetic energy in that substance. 5. Particles have energy as well as kinetic energy. a. Potential energy is energy. b. Chemical potential energy as particles get farther apart and as the particles become closer together. B. Thermal Energy 1. The total kinetic and potential energy of an object is a measure of its. 2. An object s state of matter can be changed by adding or removing. 3. Adding thermal energy to an object causes the particles to move faster (increased (increased energy), or to get farther apart energy), or to do both. C. Solid to Liquid or Liquid to Solid 1. When enough thermal energy is added, a solid changes to a(n) ; this process is called. 2. When enough thermal energy leaves a liquid, the liquid changes to a(n) ; this process is called. States of Matter 27

5 Lesson Outline continued D. Liquid to Gas or Gas to Liquid 1. A liquid changes to a gas during the process of. 2. If the vaporization occurs within a liquid, the process is called. 3. Vaporization that occurs only at the surface of the liquid is called. 4. The change of state from a gas to a liquid is called. E. Solid to Gas or Gas to Solid 1. is the change of state from a solid to a gas without going through the liquid state. 2. is the change of state from a gas to a solid without going through the liquid state. F. States of Water 1. The only substance that exists naturally on Earth in all three states is. 2. When you add energy to ice, the temperature of the ice increases, which means that the molecules increases. energy of the water a. At the point of water (0 C), water molecules vibrate so fast that they begin to move out of their places and melting occurs. b. Once a substance melts, the average energy of its particles begins to increase again as more added. c. When water reaches its point (100 C), liquid water begins to change to water. 3. When thermal energy is removed from water vapor, it at 100 C, and the liquid water at 0 C. energy is G. Conservation of Mass and Energy 1. Matter and are always conserved during a change of state. 2. Matter changes form during a change of state, but it is. 3. Energy is or released during a change of state, but it is conserved during this change. 28 States of Matter

6 MiniLab LESSON 2: 20 minutes How can you make a water thermometer? What causes liquid in a thermometer to rise and fall? Procedure 1. Read and complete a lab safety form. 2. Place one drop of food coloring in a flask. Fill the flask to the top with room temperature tap water. Over a sink or pan, insert a one-holed stopper fitted with a glass tube into the flask. Press down gently. The liquid should rise partway into the tube. Mark the level of the water with a grease pencil. 3. Holding the tube by its neck, lower the flask into a pan of hot water. Observe the water level for 3 min. Record your observations in the Data and Observations section below. 4. Remove the flask from the hot water, and lower it into a pan of ice water. Observe the water level for 3 min, and record your observations. Data and Observations Analyze and Conclude Key Concept Explain what happens to the column of water and the water particles as they are heated and cooled. States of Matter 29

7 Content Practice A LESSON 2 Changes in State Directions: On the line before each definition, write the letter of the term that matches it correctly. Each term is used only once. 1. temperature at which a solid state changes to a liquid state 2. can result from adding or removing thermal energy 3. the change of state from a gas to a liquid 4. temperature at which matter changes from liquid to solid 5. stored energy resulting from the interactions between particles or objects 6. vaporization that occurs only at the surface of a liquid 7. the energy an object has due to its motion 8. gas becomes solid without first becoming liquid 9. total potential and kinetic energy of an object 10. solid becomes gas without first changing to liquid 11. measure of the average kinetic energy of all the particles in an object 12. kinetic energy stops increasing and the potential energy starts increasing 13. change in state from a liquid to a gas A. boiling point B. change of state C. condensation D. deposition E. evaporation F. freezing point G. kinetic energy H. melting point I. potential energy J. sublimation K. temperature L. thermal energy M. vaporization 30 States of Matter

8 Content Practice B LESSON 2 Changes in State Directions: On each line, write the term from the word bank that correctly describes what happens during each change of state. Each term is used only once. condensation deposition freezing melting sublimation vaporization 1. solid to liquid 2. liquid to solid 3. liquid to gas 4. gas to liquid 5. solid to gas 6. gas to solid Directions: Answer each question on the lines provided. 7. How can you change an object s state of matter? 8. What are the two types of vaporization? 9. When matter changes state, what two things are always conserved? States of Matter 31

9 Language Arts Support LESSON 2 Word-Family Activity: Word Chart Different words can be categorized as different parts of speech. Nouns name people, places, things, or ideas. Verbs express action. Some verbs can be turned into nouns by adding the ending tion. Sometimes the final letter of the verb form of the word is dropped or changed or another letter is added before adding the tion ending. Verb translate converse expect Noun translation conversation expectation Directions: Complete the chart below with the correct word forms. Verb Noun vaporize condensation 3. sublime deposit 6. conserve evaporation attraction States of Matter

10 Language Arts Support LESSON 2 Word-Usage Activity: Building Adjectives with ed Endings An adjective is a word that modifies a noun or pronoun, and a verb expresses an action. Usually when you add ed at the end of a verb it changes the tense, but some verbs can be turned into adjectives by adding the ending. Verb increase absorb Adjective increased absorbed The recent heavy rain caused increased water levels in regional lakes. The absorbed dye colored the cloth bright blue. Directions: In each sentence below, circle the ed adjective and underline the noun that it describes. 1. Vaporized water is not visible, but it is in the air around us. 2. Greater kinetic energy results in an increased temperature. 3. In the morning, condensed water can be seen on leaves and grass. 4. The melted metal was poured into molds. 5. An evaporated liquid becomes a gas. 6. To become recycled aluminum, the metal must first be changed from a solid to a liquid and then changed back to a solid. 7. When the ball was close to the ground, it had decreased potential energy. 8. The melted snow ran in little channels off the roof. States of Matter 33

11 School to Home LESSON 2 Changes in State Directions: Use your textbook to respond to each statement. 1. The particles that make up matter have kinetic energy and potential energy. Compare and contrast kinetic energy and potential energy. 2. Thermal energy and temperature are both related to the energy of particles. Identify how thermal energy and temperature are different. 3. The common states of matter on Earth are solid, liquid, and gas. Name and describe two kinds of changes in state. 4. Water is the only substance that exists naturally as a solid, liquid, and a gas within Earth s temperature range. Identify the temperature at which water melts and the temperature at which water boils. 5. When a substance changes state, matter and energy are conserved. Explain how energy can be conserved if a substance must gain or lose thermal energy to change state. 34 States of Matter

12 Key Concept Builder LESSON 2 Changes in State Key Concept How is temperature related to particle motion? Directions: Circle the term in parentheses that correctly completes each sentence. 1. (Kinetic, Potential) energy is the energy an object has due to its motion. 2. The (faster, slower) particles move, the more kinetic energy they have. 3. Particles in the (solid, gaseous) state have the most kinetic energy. 4. Temperature is the measure of the average kinetic (substance, energy) of all particles in an object. 5. When the temperature of a substance (increases, decreases), particles move slower. 6. Potential energy (increases, decreases) as particles get farther apart. 7. Thermal energy is the (product, sum) of potential and kinetic energy. 8. When thermal energy is added to a liquid, kinetic energy (increases, decreases). 9. As a liquid changes to a (gas, solid), the particles move farther apart States of Matter 35

13 Key Concept Builder LESSON 2 Changes in State Key Concept How are temperature and thermal energy different? Directions: Respond to each statement in the space provided. 1. Describe what happens as a solid begins to change to a liquid. 2. Describe what happens to the temperature when it reaches the melting point of the matter. 3. Describe what happens to the thermal energy when it reaches the melting point of the matter. Explain. 4. Describe what happens when the solid melts completely. 5. Explain how temperature and thermal energy are different. 36 States of Matter

14 Key Concept Builder LESSON 2 Changes in State Key Concept What happens to thermal energy when matter changes from one state to another? Directions: On each line, write the term from the word bank that correctly completes each sentence. Use the diagram to answer each question. condensation freezing melting vaporization Sublimation add thermal energy Melting Vaporization add thermal energy add thermal energy Freezing Condensation Solid remove thermal energy Liquid remove thermal energy Gas Deposition remove thermal energy 1. If thermal energy is added to a liquid, the following change occurs: 2. If thermal energy is added to a solid, the following change occurs: 3. If thermal energy is removed from a liquid, the following change occurs:. 4. If thermal energy is removed from a gas, the following change occurs: States of Matter 37

15 Key Concept Builder LESSON 2 Changes in State Key Concept What happens to thermal energy when matter changes from one state to another? Directions: Complete the diagram by writing the numbers of the statements in the correct circle. 1. Vaporization occurs when a liquid is changed to a gas. 2. Melting occurs when a solid is changed to a liquid. 3. Condensation occurs when a gas is changed to a liquid. 4. Sublimation occurs when a solid is changed to a gas without going through the liquid state. 5. During boiling, vaporization occurs within a liquid. 6. During freezing, a liquid is changed to a solid. 7. During evaporation, vaporization occurs only at the surface of a liquid. 8. Deposition occurs when a gas is changed to a solid without going through the liquid state. Change of State Thermal Energy Is Added Thermal Energy Is Removed 38 States of Matter

16 Enrichment LESSON 2 Plasma The Fourth State of Matter What is the most common state of matter in the universe? You might be surprised to learn that it isn t a solid, a liquid, or a gas. It is a fourth state of matter known as plasma. Scientists estimate that plasma makes up as much as 99 percent of the visible universe. How does plasma form? After a liquid has changed to a gas, what happens if you keep adding energy? First, the molecules separate into gaseous atoms. At higher temperatures, electrons are stripped off the atoms. When you remove electrons from an atom, a positively charged particle called an ion remains. Therefore, the new substance, plasma, consists of a mixture of electrons and positively charged ions. or a plasma television. These devices use electricity, rather than heat, to strip electrons off atoms. The result is a mixture of a gas and a plasma, not a pure plasma. You might also see the effects of plasma in the aurora borealis, or Northern Lights. The colors result from plasmas in the upper atmosphere. Pure plasmas are the material of the stars, where temperatures can range from 10 million to 100 million degrees Kelvin. No material can hold matter at these temperatures. Stars such as our Sun have so much mass that gravity holds the plasma together. If scientists could re-create these temperatures on Earth, could they produce a plasma? Yes, but what would they keep it in? Unusual Properties Like a gas, plasma has no definite volume or shape. It is a fluid like liquids and gases. Plasma has some unique properties because it contains charged particles. It can carry an electrical charge and can be contained by electric or magnetic fields. Where do you find plasma? You can observe a partial plasma if you look at a fluorescent or neon light Applying Critical-Thinking Skills Directions: Answer each question. A Fifth State of Matter If plasma is produced by heating a gas to super-hot temperatures, what happens if you cool matter to a super-cold temperature? Scientists are working to find out. What they ve found so far suggests that, in a few years, we ll have to add a fifth state of matter. 1. Judge Why do science books tend to focus on three states of matter rather than four? 2. Infer The walls of fluorescent and neon lights are made of glass. Why is it possible for a solid such as glass to contain a plasma? 3. Hypothesize If scientists managed to produce a plasma on Earth, what might they keep it in? States of Matter 39

17 Challenge LESSON 2 Energy Changes in Water It takes a different amount of energy to raise the temperature of 1 g of water 1 C than it does to raise the temperature of 1 g of ice or steam 1 C. It also takes a different amount of energy to change 1 g of ice at 0 C to water at 0 C than it does to change 1 g of water at 100 C to steam at 100 C. The table shows the amount of energy needed to produce each of these changes. Energy Involved in Changes of State of Water Process Energy Required (in Joules) Raise temp. of 1 g of ice or steam 1 C. Raise temp. of 1 g of water 1 C. Change 1 g of ice (0 C) to water (0 C). Change 1 g of water (100 C) to steam (100 C) ,257 Analyze Data Use the data in the table above to answer the following questions. 1. How does the amount of energy needed to raise the temperature of 1 g of water 1 C compare to the energy needed to raise the temperature of 1 g of ice or steam 1 C? 2. About how much more energy does it take to change 1 g of water at 100 C to steam at 100 C than it takes to change 1 g of ice at 0 C to water at 0 C? 3. How much energy would you need to raise the temperature of 10 g of water 40 C? 4. You have 100 g of water at 50 C. How much energy would it take to change the water to steam at 100 C? 5. What change in energy is needed to change 1 g of steam at 100 C to ice at 0 C? 40 States of Matter

18 Skill Practice Form and Test a Hypothesis LESSON 2: 40 minutes How does dissolving substances in water change its freezing point? You know that when thermal energy is removed from a liquid, the particles move more slowly. At the freezing point, they move so slowly that the attractive forces pull them together to form a solid. What happens if the water contains particles of another substance, such as salt? You will form a hypothesis and test the hypothesis to find out. Materials 50-mL graduated cylinder triple-beam balance beaker styrene cup distilled water Also needed: balloons, ice, salt, test tubes, thermometers Learn It To form a hypothesis is to propose a possible explanation for an observation that is testable by a scientific investigation. You test the hypothesis by conducting a scientific investigation to see whether the hypothesis is supported. Try It 1. Read and complete a lab safety form. 2. Form a hypothesis that answers the question in the title of the lab. Record your hypothesis. 3. Use the data table to record your measurements. Water Salt water Time (min) Temperature ( C) Time (min) Temperature ( C) States of Matter 41

19 Skill Practice continued 4. Use a triple-beam balance to measure 5 g of table salt (NaCl). Dissolve the 5 g of table salt in 50 ml of distilled water. 5. Place 40 ml of distilled water in one large test tube. Place 40 ml of the salt-water mixture in a second large test tube. 6. Measure and record the temperature of the liquids in each test tube. 7. Place both test tubes into a large foam cup filled with crushed ice-salt slush. Gently rotate the thermometers in the test tubes. Record the temperature in each test tube every minute until the temperature remains the same for several minutes. Apply It 8. How does the data tell you when the freezing point of the liquid has been reached? 9. Was your hypothesis supported? Why, or why not? 10. Key Concept Explain your observations in terms of how temperature affects particle motion and how a liquid changes to a solid. 42 States of Matter