investigating chemicalreactions teacher's...

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Teacher's Guide

InvestigatingChemical Reactions

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Table of Contents2

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A Message from our Company

Viewing Clearances

Use and Copyright

National Standards Correlations

Student Learning Objectives

Assessment

Introducing the Program

Program Viewing Suggestions

Video Script

Answer Key to Student Assessments

Answer Key to Student Activities

Pre-Test

Post-Test

Video Review

Vocabulary

Writing Activity

Reactions Around Us

Chemical and Physical Changes

Indicators of Chemical Reactions


National Standards CorrelationsBenchmarks for Science Literacy(Project 2061 - AAAS) Grades 3-5

National Science Education Standards(Content Standards: K-4, National Academy of Sciences)

The Physical Setting - The Structure of Matter (4D)

Life Science - Content Standard C

As a result of their activities in grades K-4, all students should develop an understanding of:

By the end of the 5th grade, students should know that:

• Heating and cooling cause changes in the properties of materials. Many kinds of changes occur faster under hotter conditions.

• When a new material is made by combining two or more materials, it has properties that are different from the original materials. For that reason, a lot of different materials can be made from a small number of basic kinds of materials.

• There are groups of elements that have similar properties, including highly reactive metals, less reactive metals, highly reactive nonmetals (such as chlorine, fl uorine, and oxygen), and some almost completely nonreactive gases (such as helium and neon). An especially important kind of reaction between substances involves combination of oxygen with something else - as in burning or rusting. Some elements don’t fi t into any of the categories; among them are carbon and hydrogen, essential elements of living matter.

By the end of the 8th grade, students should know that:

• Objects have many observable properties, including size, weight, shape, color, temperature, and the ability to react with other substances. Those properties can be measured using tools, such as rulers, balances, and thermometers.

• Substances react chemically in characteristic ways with other substances to form new substances (compounds) with different characteristic properties. In chemical reactions, the total mass is conserved. Substances often are placed in categories or groups if they react in similar ways; metals is an example of such a group.

As a result of their activities in grades 5-8, all students should develop an understanding of:


Student Learning ObjectivesUpon viewing the video and completing the enclosed student activities, students will be able to do the following:

• Defi ne a chemical reaction as a process in which substances undergo changes to produce new materials with different properties.

• Provide an example of a chemical reaction, and describe the changes that occur.

• List some of the indicators of chemical reactions including: a change in color, formation of gas, a change of temperature, creation of electrical energy, and the formation of light energy.

• Identify one or more indicators when given a chemical reaction.

• Explain that reactants are substances that enter a chemical reaction, and products are substances that are produced as the result of a chemical reaction.

• Identify the reactants and products in a chemical reaction described by the instructor.

• Understand that a chemical formula is a combination of symbols that represent the elements in a compound.

• Use chemical formulas to represent a chemical reaction.

• Identify the reactants and products in a chemical reaction symbolized by chemical formulas.

• Understand that not all chemical reactions are the same, and that there are several major types of chemical reactions.

• Differentiate between a synthesis reaction and a decomposition reaction.

• Provide a specifi c example of a synthesis reaction and a decomposition reaction.

• Explain that in chemical reactions, energy is either absorbed or released.

• Understand that in an exothermic reaction, energy is released.

• Describe an endothermic reaction as a type of chemical reaction in which energy is taken in.

• Provide specifi c examples of both exothermic and endothermic reactions.


The Post-Test can be utilized as an assessment tool following student completion of the program and student activities. The results of the Post-Test can be compared against the results of the Preliminary Test to assess student progress.

The Preliminary Test is an assessment tool designed to gain an understanding of students’ preexisting knowledge. It can also be used as a benchmark upon which to assess student progress based on the objectives stated on the previous pages.

Assessment

Preliminary Test (p. 14-15):

Video Review (p. 18):

Post-Test (p. 16-17):

The Video Review can be used as an assessment tool or as a student activity. There are two sections. The fi rst part contains questions displayed during the program. The second part consists of a fi ve-question video quiz to be answered at the end of the video.


Introducing the Program

Program Viewing SuggestionsThe student master “Video Review” (p. 18) is provided for distribution to students. You may choose to have your students complete this master while viewing the program or do so upon its conclusion.

The program is approximately 14 minutes in length and includes a fi ve-question video quiz. Answers are not provided to the Video Quiz in the video, but are included in this guide on page 12. You may choose to grade student quizzes as an assessment tool or to review the answers in class.

The video is content-rich with numerous vocabulary words. For this reason you may want to periodically stop the video to review and discuss new terminology and concepts.

Before showing the video to your students obtain an antacid tablet that fi zzes in water, and hold it up in front of the class. Ask students to describe some of the properties of the tablet. Next, ask for a student volunteer to break up the tablet into smaller pieces. Ask students to describe how the tablet has changed. Ask them: Is it the same substance or is it a different substance now? Write the term “Physical Change” on the board. Discuss the meaning of this term.

Obtain a beaker of water. In front of the class drop the bits of tablet into the beaker of water. Tell students to describe their observations. After several minutes ask them how the bits of tablet have changed. Explain that the bits of tablet underwent a chemical reaction. Write the term “Chemical Reaction” on the board. Tell students that a chemical reaction is a process in which substances undergo changes to produce new materials with different properties. Ask students to list any other chemical reactions with which they are familiar. Tell students to pay close attention to the video to learn more about chemical reactions.


Video Script 1. This beautiful scene occurs every fall in northern North America as the... 2. ...leaves on trees change from their summer-time color of dark green to brilliant

reds, oranges and yellows. 3. What is going on in these leaves to cause this change? 4. It’s amazing that this sticky, gooey batter... 5. ...when cooked can transform itself into something we can eat. 6. What is responsible for this change? 7. And, isn’t it remarkable that these cold, hard pieces of wood... 8. ... can release incredible amounts of heat energy when burned. Why do these

changes occur? 9. These changes are all the result of chemical reactions.10. What are chemical reactions?11. How they be detected?12. What are some of the different types of chemical reactions?13. And, how do they occur?14. During the next few minutes we are going to answer these questions and others as

we investigate chemical reactions.15. Graphic Transition – What are Chemical Reactions?16. Every time you fry an egg...17. ...eat food...18. ...or watch fi reworks you are experiencing chemical reactions.19. Chemical reactions are all around you even though you may not notice them.20. So, what exactly is a chemical reaction?21. A chemical reaction is a process in which substances undergo changes to produce

new materials with different properties.22. For example, when we burn a piece of paper, a chemical reaction occurs.23. You Compare! What does the paper look like after it is burned?24. Before the chemical reaction occurred, the paper was white, smooth, and shiny.25. But, following the chemical reaction the burned paper is black, crumbly, and fragile.26. The paper was transformed into a new substance referred to as ash. The ash has

new and very different properties from the original paper.27. Not only does the burned paper look physically different, but it is a new substance

chemically.28. Graphic Transition – Clues to Chemical Reactions29. Even though chemical reactions occur in many places, they’re not always easy to

detect.30. Let’s talk about some clues that may indicate the presence of chemical reactions.31. One of the major indicators of a chemical reaction is a change in color.32. For example, when a metal called iron reacts with oxygen in the air,...33. ... an orangish color develops over time indicating a chemical reaction has taken

place. This process involves the oxidation of iron, commonly called rusting.


Video Script34. The plants in this garden are also carrying out a very important chemical reaction

called photosynthesis.35. Photosynthesis is the process by which plants use light energy, carbon dioxide, and

water to produce simple sugars, and a gas called oxygen.36. Without the process of photosynthesis we wouldn’t have any fruits and vegetables to

eat, or oxygen to breathe.37. The formation of oxygen gas in photosynthesis is one clue that a chemical reaction

is occurring.38. These antacid pills produce a gas when mixed with water, indicating that a chemical

reaction is taking place.39. Another good indicator that a chemical reaction is occurring is a change in

temperature.40. For example, when the chemicals in this fl are are burned, heat energy is given off.41. This also occurs when wood burns.42. You Observe! What form of energy is this glow stick giving off?43. That’s right, the glow stick is giving off light energy. The emission of light energy is

another indicator of the presence of chemical reactions.44. Other forms of energy, such as electrical energy can also be released as a result

of chemical reactions. For instance, when the chemicals in a battery react, they produce electricity.

45. These are just a few of the many different clues to the presence of chemical reactions.

46. Graphic Transition – Describing Chemical Reactions47. There are two main types of substances in chemical reactions: reactants and

products. Reactants are substances that enter a reaction, and products are substances that are produced as the result of a reaction.

48. Let’s take a look at a simple chemical reaction between iron in this nail and oxygen in the surrounding air.

49. In this case the reactants are iron and oxygen.50. When combined, these reactants form a new substance which we commonly call

rust, or more specifi cally, iron oxide.51. The product in this reaction is the iron oxide which is a new substance that did not

exist before the chemical reaction took place. 52. If you’ve ever played music you know that these markings symbolize musical notes.53. Similarly in chemistry, chemical symbols are used to represent different elements

and compounds.54. You may be familiar with the symbol for hydrogen which is H, and the symbol for

oxygen which is O.55. And, chances are you’ve heard of the chemical formula for water – H

2O.

56. A chemical formula is a combination of symbols that represent the elements in a compound.


Video Script57. In the case of water, the 2 below the H is called a subscript. It indicates that there

are two atoms of hydrogen.58. Just as words are strung together to make meaningful sentences,...59. ...chemical formulas can be strung together to symbolize chemical reactions.60. For example, the chemical reaction between sodium and chlorine is symbolized by

the following equation that begins with... 61. ...2Na which stands for two molecules of sodium. The + sign means that sodium

reacts with the next reactant Cl2. The subscript 2 means there are two atoms of

chlorine.62. The arrow indicates the reaction produces or equals the products to the right.63. In this case, the product consists of two molecules of sodium chloride, a new

substance produced from the reaction.64. You Decide! Is this chemical equation for photosynthesis simpler, or more complex

than the previous equation?65. The chemical equation for photosynthesis is more complex than the reaction in

which sodium chloride is produced.66. Some chemical equations involve many reactants that produce many complex

products.67. It is important to note, that regardless of the complexity of a chemical reaction,

the change that occurs involves the rearrangement of atoms, not the destruction of matter.

68. In other words, all the atoms that were present in the beginning as reactants are also present at the end of the reaction in the products.

69. Graphic Transition – Types of Chemical Reactions70. There are thousands of known chemical reactions.71. To help scientists better organize and study them they are often classifi ed according

to their similarities.72. In a type of reaction called a synthesis reaction, two or more substances are

combined to make a more complex single substance.73. This occurs when carbon dioxide reacts with water to from carbonic acid – a more

complex single compound.74. This also occurs when magnesium metal burns and combines with oxygen to form a

more complex substance called magnesium oxide.75. Another group of reactions is called decomposition reactions. You are probably

familiar with the decomposition of leaves. 76. In a decomposition reaction a complex substance breaks down to form two or more

simpler substances. In a way, a decomposition reaction is the reverse of a synthesis reaction.

77. An example of a decomposition reaction occurs when hydrogen peroxide, a substance used to disinfect cuts, decomposes into water and oxygen gas.

78. Graphic Transition – Energy and Chemical Reactions79. In chemical reactions energy is either absorbed or released.


Video Script 80. You Decide! Is energy absorbed or released as wood burns? 81. When wood burns you can feel energy being released. This is called an exothermic

reaction. 82. In an exothermic reaction, energy is released. 83. Quite often in exothermic reactions light is also released. 84. The reverse, or opposite, of an exothermic reaction is an endothermic reaction. 85. In endothermic reactions energy is absorbed or taken in. 86. The chemicals in this cold pack are interacting to form an endothermic reaction. 87. It is important to note that not all chemical reactions occur at the same rate. 88. Some reactions, such as the explosion of fi reworks are very fast. 89. While others such as the rusting of metal are slower. 90. There are many factors that affect the speed at which reactions occur including the

concentration of reactants, the temperature, and the amount of surface area they have to name just a few.

91. Graphic Transition – Summing Up 92. During the past few minutes we have explored some of the fascinating

characteristics of chemical reactions. 93. Some of the clues, or indicators of the presence of chemical reactions were

highlighted including changes in color, temperature, and the production of gas to name just a few.

94. We then discussed how chemical reactions are explained through the use of chemical symbols and chemical equations.

95. Some of the types of chemical reactions were highlighted including synthesis and decomposition reactions.

96. Last we briefl y discussed how reactions can release or absorb energy. 97. So, the next time you warm yourself by a fi re,... 98. ... or cook some food... 99. ... think about some of the things we discussed during the past few minutes.100. You just might think about chemical reactions a little differently.101. Graphic Transition – Video AssessmentFill in the correct word to complete the sentence. Good luck and let’s get started.1. A chemical ____ is a process in which substances undergo changes to make new

substances.2. An indication of a chemical reaction is the production of ___.3. ____ are substances that enter a reaction.4. This is an example of a chemical _____.5. In an exothermic reaction energy is ___.


Answer Key to Student AssessmentsPre-Test (p. 14-15) Post-Test (p. 16-17)

Video Review (p. 18)

1. c - a chemical reaction 2. a - new materials 3. d - color 4. b - temperature 5. c - enter the reaction 6. a - product 7. d - chemical formula 8. c - combined 9. a - destroyed10. b - released11. true12. false13. true14. true15. false16. Possible indicators to the presence of chemical reactions include: color change, temperature change, gas production, or the emission of light.17. Products are the substances that are produced as the result of a chemical reaction.18. Examples of chemical formulas of common substances include: H

2O (water), CO

2 (carbon

dioxide), and NaCL (salt).19. Reactants are substances that enter a chemical reaction. Products are substances that are formed as a result of a chemical reaction. 20. The forming of rust, photosynthesis, and respiration are all examples of chemical reactions.

1. c - combined 2. c - enter the reaction 3. b - released 4. c - a chemical reaction 5. d - chemical formula 6. a - destroyed 7. a - new materials 8. b - temperature 9. a - product10. d - color11. true12. true13. true14. false15. false16. Reactants are substances that enter a chemical reaction. Products are substances that are formed as a result of a chemical reaction. 17. Examples of chemical formulas of common substances include: H

2O (water), CO

2 (carbon

dioxide), and NaCL (salt).18. Possible clues to the presence of chemical reactions include: color change, temperature change, gas products, or the emission of light.19. The forming of rust, photosynthesis, and respiration are all examples of chemical reactions. 20. Products are the substances that are produced as the result of a chemical reaction.

1. The paper is black, crumbly, and fragile after it has been burned.2. The glow stick is giving off light energy.3. The chemical equation for photosynthesis is more complex than the reaction in which sodium chloride is produced.4. Energy is being released when wood burns. This is called an exothermic reaction.

1. A chemical reaction is a process in which substances undergo changes to make new substances.2. An indication of a chemical reaction is the production of gas.3. Reactants are substances that enter a reaction.4. This is an example of a chemical equation.5. In an exothermic reaction energy is released.


Writing Activity (p. 20)

Vocabulary (p. 19 )

Answer Key to Student Activities

In Your Own Words (p. 20)

1. chemical reaction 2. color change 3. reactants 4. products 5. chemical symbols 6. chemical equation 7. synthesis reaction 8. decomposition reaction 9. exothermic reaction10. endothermic reaction

A chemical reaction is a process in which substances undergo changes to produce new materials with different properties. Chemical reactions are all around you even though you may not notice them. One of the major clues, or indicators, of a chemical reaction is a change in color. Another indicator that a chemical reaction is occurring, such as when wood is burned, is a change in temperature. There are two main types of substances in chemical reactions. Reactants are substances that enter a reaction. Products are substances that are produced as the result of a reaction. In expressing chemical reactions, chemical symbols are used to represent different elements and compounds. A chemical formula is a combination of symbols that represent the elements in a compound. For example, water is symbolized as follows: H

2O. Just as words are strung together to make

meaningful sentences, chemical formulas are strung together to symbolize chemical reactions. Regardless of the complexity of a chemical reaction, the change that occurs involves the rearrangement of matter, not the destruction of matter.

1. A chemical reaction is a process in which substances undergo changes to produce new materials with different properties.2. Examples of indicators of the presence of chemical reactions include: color change, temperature change, emission of light energy, and gas production.3. In an exothermic reaction energy is released. Examples of exothermic reactions include the burning of wood, an explosion, and the setting of cement.

Reactions Around Us (p. 21-22 )1. F2. C3. A4. G5. E6. B7. D

Chemical and Physical Changes (p. 23)A. This is an example of a physical change. The paper changed size and shape but did not chemically change.B. A chemical change occurred as the egg was cooked, turning white into a slightly different substance.C. This is an example of a physical change called a phase change. The liquid is still water.

Indicators of Chemical Reactions (p. 24-25 )Reactants How to Initiate the

Chemical ReactionObservation Chemical

Reaction Indicators

Baking Soda and Vinegar

Obtain a beaker, small amount of baking soda and small amount of vinegar. Put the baking soda in the beaker, slowly pour vinegar on top of baking soda.

The reactants bubbled and produced a gas.

Gas production

Glow Stick Follow the directions on the package to “light” glow stick.

When pressure was applied, the material inside the stick emitted light.

The emission of light is the indicator

Antacid or Cold Tablet and Water

Place some water in a beaker. Place the tablet in the water.

When the tablet was dropped in the water, it fi zzed.

Gas production

Foot/hand warmer

Follow the directions on the package to start the reaction.

When pressure was applied the packet became hot.

Temperature change

Match Under teacher supervision light a match and blow out after 5 seconds. If you do not feel comfortable lighting the match, have your teacher do it.

Match tip burned. Change in temperature and light given off

Ice Pack Follow the directions on the package to start the reaction.

As pressure was applied the packet became cold.

Temperature change

Pre-Test

4. When something burns, a good indicator that a chemical reaction has occurred is a change in:

5. In a chemical reaction, the reactants are substances that:

1. A burning piece of paper is an example of:

2. A chemical reaction is a process in which substances undergo changes to produce:

3. In the chemical reaction between iron and oxygen an orange substance referred to as rust is formed. The clue a chemical reaction has occurred is a change in:

Circle the best answer for each of the following questions.

6. When sodium and chlorine react, a substance called sodium chloride, also known as salt, is formed. In this reaction salt is referred to as a(n):

10. In an exothermic reaction, such as in the burning of wood, energy is:

7. The compound water is symbolized by H2O. This is referred to as a(n):

8. In a type of reaction called a synthesis reaction, two or more substances are:

9. In a chemical reaction, atoms are rearranged, but matter is not:

a. photosynthesis b. respiration c. a chemical d. an endothermic reaction reaction

a. new materials b. life c. plastics d. negative energy

a. temperature b. density b. density b. density c. energy c. energy c. energy d. color

a. are produced a. are produced a. are produced b. explode c. enter the d. stay the same reaction

a. phase b. temperature c. pH c. pH c. pH d. size

a. product a. product a. product b. reactant b. reactant b. reactant c. transition d. metal element

a. equation b. single c. atom d. chemical formula element

a. negated a. negated a. negated b. grown c. combined d. deleted

a. destroyed a. destroyed a. destroyed b. rearranged c. changed c. changed c. changed d. altered

a. absorbed a. absorbed a. absorbed b. released b. released b. released c. taken d. chilled

Visual Learning Company

Page

14Investigating Chemical ReactionsInvestigating Chemical ReactionsInvestigating Chemical

Name

Write a short answer for each of the following.

Pre-Test

16. State one clue that helps indicate a chemical reaction has occurred.

17. What are the products in a chemical reaction?

18. Write an example of a chemical formula of a common substance.

11.

12.

13.

14.

15.

Write true or false next to each statement.

19. What is the difference between reactants and products in a chemical reaction?

20. What is an example of a chemical reaction?

One of the major indicators of a chemical reaction is a change in color.

Reactants are substances that are produced as the result of a reaction.

A chemical formula is a combination of symbols that represent elements in a compound.

Regardless of the complexity of a chemical reaction, the change that occurs involves the rearrangement of atoms, not the destruction of matter.

There is just one main type of chemical reaction.


Page


Name

Circle the best answer for each of the following questions.

Post-Test

1. In a type of reaction called a synthesis reaction, two or more substances are:

a. negated a. negated a. negated b. grown c. combined d. deleted

2. In a chemical reaction, the reactants are substances that:

a. are produced a. are produced a. are produced b. explode c. enter the d. stay the same reaction

3. In an exothermic reaction, such as in the burning of wood, energy is:

a. absorbed a. absorbed a. absorbed b. released b. released b. released c. taken d. chilled

4. A burning piece of paper is an example of:

a. photosynthesis b. respiration c. a chemical d. an endothermic reaction reaction

5. The compound water is symbolized by H2O. This is referred to as a(n):

a. equation b. single c. atom d. chemical formula element

6. In a chemical reaction, atoms are rearranged, but matter is not:

a. destroyed a. destroyed a. destroyed b. rearranged c. changed d. altered

7. A chemical reaction is a process in which substances undergo changes to produce:

a. new materials b. life c. plastics d. negative energy

8. When something burns, a good indicator that a chemical reaction has occurred is a change in:

a. phase b. temperature c. pH c. pH c. pH d. size

9. When sodium and chlorine react, a substance called sodium chloride, also known as salt, is formed. In this reaction salt is referred to as a(n):

a. product a. product a. product b. reactant b. reactant b. reactant c. transition d. metal element

10. In the chemical reaction between iron and oxygen an orange substance referred to as rust is formed. The clue a chemical reaction has occurred is a change in:

a. temperature b. density b. density b. density c. energy c. energy c. energy d. color


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Name

Post-Test

Write a short answer for each of the following.

16. What is the difference between reactants and products in a chemical reaction?

17. Write an example of a chemical formula of a common substance.

18. List a clue that helps identify if a chemical reaction has occurred.

11.

12.

13.

14.

15.

Write true or false next to each statement.

19. What is an example of a chemical reaction?

20. What are products in chemical reactions?

Regardless of the complexity of a chemical reaction, the change that occurs involves the rearrangement of atoms, not the destruction of matter.

A chemical formula is a combination of symbols that represent elements in a compound.

One of the major indicators of a chemical reaction is a change in color.

There is just one main type of chemical reaction.

Reactants are substances that are produced as the result of a reaction.


Page


Name

1. A chemical _______________ is a process in which substances undergo changes to make new substances.

2. An indication of a chemical reaction is the production of _______________.

3. _______________ are substances that enter a reaction.

4. This is an example of a chemical _______________.

5. In an exothermic reaction energy is _______________.

After you watch the video, test your knowledge with these questions.

While you watch the video, answer these questions:

Video Review

1. What does the paper look like after it is burned?

2. What form of energy is this glow stick giving off?

3. Is this chemical equation for photosynthesis simpler, or more complex than the previous equation?

You Observe!

You Decide!

You Compare!

4. Is energy absorbed or released as wood burns?

You Decide!


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Name

VocabularyUse these words to fi ll in the blanks next to the sentences below.

1.

7.

2.

6.

8.

4.

5.

3.

9.

10.

Wo

rds

A process in which substances undergo changes to produce new materials with different properties.

One clue indicating the possible presence of a chemical reaction.

Substances that enter a reaction.

Substances that are produced as the result of a reaction.

Used to represent different elements or compounds.

A way to express the reactants and products in a chemical reaction.

A type of reaction in which two or more substances are combined to make a more complex substance.

A type of reaction in which a complex substance breaks down to form two or more simpler substances.

Energy is released in this type of reaction; wood burning is an example.

Energy is taken in or absorbed in this type of reaction.

chemical symbols synthesis reaction endothermic reaction reactants chemical symbols synthesis reaction endothermic reaction reactants

chemical equation products chemical reaction decomposition reaction color change exothermic reaction decomposition reaction color change exothermic reaction decomposition reaction color change exothermic reaction decomposition reaction color change exothermic reaction decomposition reaction color change exothermic reaction


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Name

2. List three indicators used to identify the presence of chemical reactions.

1. What is a chemical reaction?

Use the correct word from above to complete the sentences in the following paragraph.

Writing Activity

In Your Own Words

3. What is an exothermic reaction? Provide an example.

Wo

rds

indicators products chemical reactions properties symbolsindicators products chemical reactions properties symbols

changes formula reactants destruction temperature

A chemical reaction is a process in which substances undergo ______________ to produce new materials with different _______________. Chemical reactions are all around you even though you may not notice them. One of the major clues, or _______________ of a chemical reaction is a change in color. Another indicator that a chemical reaction is occurring, such as when wood is burned, is a change in _______________. There are two main types of substances in chemical reactions. _______________ are substances that enter a reaction. ________________ are substances that are produced as the result of a reaction. In expressing chemical reactions, chemical ____________ are used to represent different elements and compounds. A chemical _______________ is a combination of symbols that represent the elements in a compound. For example, water is symbolized as follows: H

2O. Just as words

are strung together to make meaningful sentences, chemical formulas are strung together to symbolize _______________ _______________. Regardless of the complexity of a chemical reaction, the change that occurs involves the rearrangement of matter, not the ______________of matter.


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Name

Reactions Around UsBackground: Every time you fry an egg, eat food, take a breath of air, or watch fi reworks, you are experiencing chemical reactions. Chemical reactions are all around you even though you may not notice them. What exactly is a chemical reaction? A chemical reaction is a process in which substances undergo changes to produce new materials with different properties. For example, when paper is burned it undergoes a chemical reaction. Before the chemical reaction occurred the paper was white, smooth, and shiny. But, following the chemical reaction the burned paper was black, crumply, and fragile. The paper was transformed into a new substance referred to as ash, with different properties. Not only does the paper look physically different, but it is a new substance chemically.

Directions: In this activity you are provided with a list of chemical reactions. Match the reaction to its description on the right. After completing the activity, create your own examples and descriptions on the next page. Test your classmates to see if they can fi nd the correct match.

______ 1. Respiration

______ 2. Photosynthesis

______ 3. Rust

______ 4. Match burning

A. Objects containing iron react with oxygen to produce this orangish substance.

B. In this reaction gasoline is combusted (burned) to create mechanical energy. Waste gases and heat are also given off.

C. In this chemical reaction plants take in carbon dioxide and water. With light from the sun they produce simple sugars and oxygen.

D. A chemical reaction between this substance high in the atmosphere and human-made complex compounds referred to as CFCs cause the layer to diminish, exposing us to harmful rays of the sun.


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______ 5. Tarnish on spoon

______ 6. Car engine using gasoline

______ 7. Destruction of ozone layer in atmosphere

______ 8. __________________

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______ 9. __________________

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______ 10. __________________

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Reactions Around Us

H. ______________________________________

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I. _______________________________________

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J. ______________________________________

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Directions: Create your own examples and descriptions in the blanks below.

E. This chemical reaction occurs between silver and hydrogen sulfi de in the air forming a residue called silver sulfi de and hydrogen gas.

F. In this process, cells in the body use oxygen and other materials to produce energy. Carbon dioxide is given off as a waste product.

G. In this chemical reaction fl ammable chemical compounds burn, releasing heat and light.


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Chemical and Physical ChangesBackground: If you break a piece of chalk in half, you have changed its original size and shape. But the two pieces are still chalk. This is an example of a physical change. A physical change is a change in size, shape or state of matter. When fi reworks explode, materials burn, or cars rust, new and different substances are formed. These are examples of chemical changes. A chemical change is a change of one substance in a material to a different substance. In this activity you will work with physical and chemical changes.

Directions: Read the following scenarios. Decide if the scenario describes a physical change or a chemical change. If you get confused about the difference between a physical change and a chemical change, reread the information in the Background. Explain your answer.

A. In this scenario a dog rips up the newspaper into small pieces so no one in the house can read it.

Describe the change:

B. You are hungry and decided to cook an egg for breakfast. You crack it into a frying pan and the outside of the egg turns white.

C. After accidently leaving some ice cubes on the counter for a few hours, you return to fi nd a puddle of water.

D. Write a scenario of your own and give it to your classmates:





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Indicators ofChemical ReactionsBackground: Even though chemical reactions occur in many places, they’re not always easy to detect. Let’s discuss some clues that may indicate the presence of chemical reactions. One of the major indicators of a chemical reaction is a change in color. For example, when a metal called iron reacts with oxygen in the air, an orangish color develops over time indicating a chemical reaction has taken place. This process involves the oxidation of iron, commonly called rusting.

Materials: safety goggles, beaker, baking soda, vinegar, glow stick, antacid tablet or cold tablet that fi zzes, match, hand/foot warmer, chemical-based ice pack

Directions:

1. Read the background and become familiar with the various indicators of chemical reactions.

2. Obtain the supplies listed in the Materials.

3. Before starting work, securely put on safety goggles. Wear the goggles throughout the entire activity.

4. On the following page is a chart listing several different chemical reactions. Follow the instructions on how to initiate each chemical reaction.

5. Record your observations. Also describe the indicators of the reaction.

The plants in a garden also carry out a very important chemical reaction called photosynthesis. Photosynthesis is the process by which plants use light energy, carbon dioxide, and water to produce simple sugars, water vapor, and a gas called oxygen. Without the process of photosynthesis we wouldn’t have any fruits and vegetables to eat, or oxygen to breathe. The formation of oxygen gas in photosynthesis is one clue that a chemical reaction is occurring. Antacid tablets also produce a gas when mixed with water, indicating that a chemical reaction is taking place.

Another good indicator of a chemical reaction is a change in temperature. For example, when the chemicals in a fl are are burned, heat energy is given off. This also occurs when wood burns. What form of energy does a glow stick give off? A glow stick gives off light energy. The emission of light energy is another indicator of the presence of chemical reactions. Other forms of energy, such as electrical energy can also be released as a result of chemical reactions. For instance, when the chemicals in a battery react, they produce electricity. These are just a few of the many different clues to the presence of chemical reactions.


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investigating chemicalreactions teacher's...

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