Chemistry - Third Year
What It Takes To Change
Basic Education Assistance for Mindanao (BEAM) project. Prior approval must be
given by the author(s) or the BEAM Project Management Unit and the source must
be clearly acknowledged.
Mind Map
The Mind Map displays the organization and relationship between the concepts and activities in this Learning Guide in a visual form. It is included to provide visual clues on the structure of the guide and to provide an opportunity for you, the teacher, to
reorganize the guide to suit your particular context.
Stages of Learning
The following stages have been identified as optimal in this unit. It should be noted that the stages do not represent individual lessons. Rather, they are a series of stages over one or more lessons and indicate the suggested steps in the development of the targeted competencies and in the achievement of the stated objectives.
Assessment
All six Stages of Learning in this Learning Guide may include some advice on possible formative assessment ideas to assist you in determining the effectiveness of that stage on student learning. It can also provide information about whether the learning goals set for that stage have been achieved. Where possible, and if needed, teachers can use the formative assessment tasks for summative assessment purposes i.e as measures of student performance. It is important that your students know what they will be assessed on.
1. Activating Prior Learning
Background or purpose
Everything you see and touch has the ability to change. Sometimes substances change to form new substances. Other times, substances change but keep the same identity. In this activity, the students will determine as to what substances will result to new substances and which will retain their identity by performing the matching game cards.
Strategy
Matching Game Cards is a game where students will match similar cards. In this activity, students will match cards that will come up with three examples of physical and chemical changes respectively.
Materials
Student Activity Sheet 1, Mix 'N Match, masking tape, manila paper, marker, envelope
Activity 1: Mix 'N Match
1. A day prior to the activity divide the class into groups of five for you to be able to determine the number of cards to prepare.
2. Reproduce Student Activity Sheet 1, Mix 'N Match, page 15. Cut out the cards and place it inside the envelope. Provide each group with the envelope with cards inside it. 3. Inform them that they should mix and match the cards and come up with three
examples of physical change and three examples of chemical change.
4. Ask them to indicate which change resulted to the formation of a new substance and which change retained the substance' physical properties such as the size, shape, color, etc.
5. Let them paste their responses on a manila paper and post them on the board. 6. Check their work. Tell them that you will revisit this activity after the discussion.
Formative Assessment
Check their responses. Expected response: paper-scissor (Physical change); salt-water (physical change); milk-vinegar (chemical change); wood-fire (chemical change); paper-match (chemical change); water-ice (physical change)
Roundup
The students should have identified substances which, when subjected to a process, result to either physical and chemical change.
2. Setting the Context
This stage introduces the students to what will happen in the lessons. The teacher sets the objectives/expectations for the learning experience and an overview how the learning experience will fit into the larger scheme.
Background or purpose
To start the unit, the students will be given an activity where they will be exposed to one of the important products used by mankind which undergoes chemical change.
Strategy
observation. The students should take a few moments (probably not minutes) just to THINK about the question.
2) Pair. Using designated partners (such as with Clock Buddies), nearby neighbors, or a desk mate, students PAIR up to talk about the answer each cameup with. They compare their mental or written notes and identify the answers they think are best, most
convincing, or most unique.
3) Share. After students talk in pairs for a few moments (again, usually not minutes), the teacher calls for pairs to SHARE their thinking with the rest of the class. She can do this by going around in round-robin fashion, calling on each pair; or she can take answers as they are called out (or as hands are raised). Often, the teacher or a designated helper will record these responses on the board or on the overhead.
Activity 2: Vinegar Making
1. Have them think about vinegar. Tell them to list the benefits of vinegar, identify its components and describe how it is produced.
2. When done, just choose at least five pairs for the presentation.
3. In the discussion, emphasize the chemical changes involved and tell the students that this is just one of the products in industry where physical change or chemical change is used during its production. Tell them that in the next activity, they will learn more on the application of these changes in society which helps improve life. Inform them of the objectives as well.
Roundup
The students should have realized that the products they use in everyday life involve physical and chemical changes.
3. Learning Activity Sequence
This stage provides the information about the topic and the activities for the students. Students should be encouraged to discover their own information.
Background or purpose
Substances can change in two ways: physically or chemically. It all happens around you. The series of experiments to be performed by the students will enable them to
differentiate physical from chemical change.
Moreover, another activity is given where students will realize the importance of these changes in everyday activities and its application which help improve the quality of life.
Strategies
Learning Centers. The idea is that the center is a physical area where the child is equipped with the appropriate tools to facilitate and challenge learning. Tools can also include learning logs, comment books, sign in charts, time limits.
For learning centers to be effective, routines, procedures and expectations of learning center use will need to be clear.
Materials for Activity 3.1
Station 1:Station 2:
cup with water, film canister (for the teacher) 2 Alka-seltzer (for each group)
Station 3:
water, 50ml graduated cylinder (for the teacher) 35 grams cornstarch, plastic bowl (for each group) Station 4:
bubble solution (for the teacher)
plastic containers (e.g margarine), drinking straw (for each group) Station 5:
3 beakers, food color, water, bleach, 2 petri dish or similar containers (for the teacher) 2 cotton swabs (for each group)
Station 6:
sulfur, alcohol lamp or hot plate (if available) (for the teacher) old spoon (for each group)
Station 7:
a choice of fruit (apple, banana, potato, eggplant), knife, vitamin C Student Activity Sheet 3.1, It's A Matter Of Change
Teacher Resource Sheet 3, Changes In Matter, page 22
Activity 3.1: It's A Matter Of Change
1. Discuss physical and chemical change. Refer to Teacher Resource Sheet 3, Changes In Matter, page 22.
2. Set up the stations prior to the activity. Place station labels and instructions and the materials needed in each station. Refer to Teacher Resource Sheet 1, It's A Matter Of Change, page 18 for the station instructions and list of materials needed.
3. Organize the students into seven teams and distribute the Student Activity Sheet 3.1, It's A Matter Of Change, page 17.
4. Have a run through of the procedure in each station to ensure that they all understand the instructions given.
5. Tell students that they have to observe cleanliness in every station that they stop. Make sure that they empty bottles or containers for the next groups to use. Clean the mess with rags. Throw the solution or mixture into the sink. In other words let them observe laboratory procedures.
6. Instruct students to rotate through all the stations. Provide at least six minutes in every station. After completing all the stations, have students work in teams to decide whether each station showed physical or chemical changes. Point out to students that more than one change may have occurred in some stations.
1. Teacher develops an assignment that requires students to create a product that will appear on poster paper.
2. Students create the product on poster paper.
3. Products are posted around the room, hallways, gym or cafeteria.
4. Teacher develops a task for students to complete as they view the products. 5. Students are placed in small groups, directed toward one product, view it much
like they would in an art gallery then complete their tasks. Students then rotate to the next product until they've had a chance to view them all or complete the assignment given by the teacher.
6. Teacher debriefs in a whole group setting.
Materials for Activity 3.2
manila paper, paste, Student Activity Sheet 3.2.a – 3.2.e, What's My Use?
Activity 3.2: What's My Use?
1. Use the same groupings as in the previous activities.
2. Paste the pictures on manila paper. One picture per manila paper. Refer to Student Activity Sheet 3.2.a – 3.2.e, What's My Use, pages 24 - 28 for the pictures.
3. Post the manila paper on the wall around the room.
4. They will now do a gallery walk activity where each group will move from one picture to another just lie in their learning station activity. The only difference here is that they will no longer perform an experiment.
5. In this activity, students will identify whether the picture depicted a physical or chemical change. They will at the same time give their opinion as to what importance could it give to the society. Each group will bring along with them a marker.
6. Discuss the activity afterwards. After the discussion, let them reflect if what they had written was correct by letting them revisit their work.
Materials for Activity 3.3
Student Activity Sheet 3.3, Heat in Chemical Reaction, page 30
Activity 3.3: Heat in Chemical Reaction
1. Divide the students into groups of five. 2. Distribute the materials to each group.
3. Let them perform the activity on exothermic and endothermic reaction. Refer to Student Activity Sheet 3.3, Heat in Chemical Reaction, page 30.
4. Conduct a post – lab activity and discuss the two types of reaction. Below are the answers for the activity:
A. Exothermic Reaction
• The temperature rises.
• An exothermic chemical reaction is a reaction that yields heat. B. Endothermic Reaction
• The temperature drops.
Note:
1) Use a laboratory thermometer for the experiment. These experiments will yield more accurate temperature results if they are performed in a Styrofoam cup instead of a glass (the glass conducts heat), but the experiments are more effective as a learning tool when students can see exactly what is taking place. Perform the experiments the first time as they are written; then repeat them using Styrofoam cups and compare the results.
2) For Endothermic experiment; in the event where ammonium nitrate is unavailable, below is an optional activity which uses different materials but yields the same result. Use the same question in each procedure.
Note: An option would be to use the following materials:
baking soda, Styrofoam cup, thermometer, stirring rod, 25 ml citric acid solution. Procedure:
1) Pour the citric acid solution in a Styrofoam coffee cup. Use a thermometer or other temperature probe to record the initial temperature.
2) Stir in the baking soda (sodium bicarbonate). Track the change in temperature.
Materials:
Student Activity Sheet 3.4.1, Fizzy Balloon, page 31, Student Activity Sheet 3.4.2 – 3.4.5, Fizzy Fun, pages 32 - 36.
Activity 3.4: Fizzy Fun
1. The first part in these series of activities is just an introductory activity where students will play a game.
2. Divide the students into four groups. Distribute the materials to each group.
3. Tell them that everyone must use 50 ml of water in their Erlenmeyer flask. The aim of the game is to inflate the balloon using the gas evolved from the reaction of Alka-seltzer in the water. For the procedure, refer to Student Activity Sheet 3.4.1, Fizzy Balloon, page 31.
4. Given the materials, the students should think of a way to increase the rate of reaction at a given time frame which will lead to an increase volume of the balloon.
5. The winner will be the group that has made their reaction go the fastest over the two minute interval and which has the balloon with the largest volume wins.
6. The familiar fizzing you hear when you drop an Alka-Seltzer tablet into a glass of water is the result of a chemical reaction. It's also the perfect tool for demonstrating some very nifty science principles; like the factors affecting the rates of chemical reactions.
8. Tell them that each group will be doing a different task from the rest. For a bigger number of students, you may wish to divide them into eight groups. But two groups will be doing the same activity.
9. Assign each group an activity to do. Refer to Student Activity Sheet 3.4.2 – 3.4.5, Fizzy Fun, pages 32 - 36.
10.Stress that Activity 3.4.5 will no longer use an Alka-Seltzer but is considered as one of the factors that affects the rate of reaction.
11.Let each group present their result and observations.
12.After all the groups have reported, start the discussion by letting them enumerate and explain the factors affecting the rate of chemical reactions. Stress that each activity corresponds to one factor.
13.Explain the ideas behind each activity. Refer to the explanation given below.
In order for a chemical reaction to occur, the particles, atoms or ions, which are reactants, must physically come in contact with one another. Anything that
increases the frequency of these encounters will increase the rate at which products are formed.
➢ Activity 3.4.2
The rate of a chemical reaction can be increased by increasing the temperature of these reactants.
➢ Activity 3.4.3
The rate of a chemical reaction is affected by the physical size of the reactants. Decreasing the size of the particles which make up a given weight will increase the number of particles represented by the same weight. Smaller particle size results in an increase in the rate of reaction because the surface area of the reactant has been increased.
➢ Activity 3.4.4
If any of the products or reactants involved in a chemical reaction are gases, the rate of reaction will decrease as pressure on the system is increased.
➢ Activity 3.4.5 – Answers for questions 1-3 1. No reaction occurred.
2. A black precipitate formed.
3. The copper (II) sulfate solution acted as a catalyst to make the reaction happen quickly enough to notice.
Refer to Teacher Resource Sheet 5, Rate of Chemical Reaction, page 37 , for additional background information.
Formative Assessment
For Activity 3.1, check their activity sheet. Use a performance rubric for Activity 3.2.
Roundup
4. Check for Understanding of the Topic or Skill
This stage is for teachers to find out how much students have understood before they apply it to other learning experiences.
Background or purpose
The several tasks done by the students gave them a thorough/deeper understanding about physical and chemical change and its importance in our everyday life. The next activity aims to check how well they understood the topic.
Strategy
Think - Pair - Share
Materials
Student Activity Sheet 4.1, What A Day!, page39
Activity 4.1: What A Day!
1. Pair the students.
2. Give the Student Activity Sheet 4.1, What A Day!, page 39 to each pair. 3. Discuss to them the procedure.
4. When done check their answers together with the class.
Activity 4.2: Changes In My Life
1. After doing the “What A Day!” activity, using the same pair let them do the next
activity where they will show how well they understood the lesson on the application of physical and chemical changes to life.
2. Have them write their own stories that incorporate physical and chemical changes. Each story should include at least three examples of each type of change and its application that improved the quality of life or that have been useful to their homes, community and society. Have them swap stories to find the changes in each other's work.
3. Let each of them list the changes in a sheet of paper. 4. Check their output.
Activity 4.3: Think Aloud
1. You will now check students' understanding on the factors that affect the rate of reaction by using the numbered heads together strategy.
2. Group the students into four. Let them count off from 1-4.
3. Call-out a question. Refer to Teacher Resource Sheet 7, Questions – Rate of Chemical Reaction, page 40 for the questions.
4. Students in teams put their heads together to discuss the answer. They must make sure everyone on the team knows the answer.
5. Randomly call a number from 1-4 (use a spinner, draw a paper out of a cup, roll a die, etc.).
7. When all the teams are ready, have the designated student stand and hold up their paper to show their answer. Check the accuracy of answers.
Formative Assessment
Answers in the activity will be checked. Refer to Teacher Resource Sheet 8 – Answer Key – Rate of Chemical Reaction, page 41.
Roundup
The students should have been able to identify the physical and chemical changes mentioned in the story.
They should have been able to write their stories that incorporate physical and chemical changes.
They should have been able to answer the questions about rate of chemical reactions.
5. Practice and Application
In this stage, students consolidate their learning through independent or guided practice and transfer their learning to new or different situations.
Background or purpose
From the previous activity, students realized that physical and chemical changes are present whatever they do. They happen anywhere even in the kitchen. In this activity, students are going to prepare a dessert that is made from physical and chemical changes.
Strategy
Practical Work
Any teaching and learning activity which involves at some point the students in observing or manipulating real objects and materials.
This strategy helps students gain an understanding of as much of the established body of scientific knowledge that is appropriate to their needs, interests and capacities.
Materials
1 can condensed milk, 2/3 cup of peanut butter, chocolate chips, cups, whipped cream, vanilla wafer, bowl, large spoon, plastic spoon
Activity 5.1: Physical And Chemical Changes Menu
1. A day before the activity, group the students into six. Give them the list of ingredients needed.
2. Inform the students that they will prepare a dessert that is prepared from physical and chemical changes.
3. Tell them to boil the can of condensed milk at home. This will be done by removing the label from the condensed milk and placing the unopened can in a pot. Cover the can with water. Boil for 45 minutes.
4. On the day of the activity, you should do it all at once wherein you will be the one to dictate the instructions one by one while they will also do it simultaneously every after instruction.
5. Instruct them to take note the part of the preparation where physical and chemical changes have taken place.
• Open the can of the heated milk (caramel) and allow the students to list their observations on the changes that had occurred in the heated can of milk.
• Pour the caramel into a bowl.
• Add ½ (approximately) of a cup of smooth peanut butter to the caramel. Stir it with a spoon. Tell them to take note of the type of change that is taking place.
• Add one container of whipped cream. Stir it again.
• Add ½ cup of chocolate chips and continue stirring
• Have other students place the containers with a vanilla wafer in it on the table. Place a spoonful of your mixture in each container. Serve and eat.
6. Call out students to share their observation during your discussion.
7. Be sure to write the recipe on the board so students may share their science activity with the family members.
8. You can tell them to make a journal specifying the physical and chemical changes that during the process. This could be presented the following day.
Activity 5.2: My Product, My Change
1. Now that the students are already familiar with the practical application of physical and chemical changes in life, they can easily do the next activity.
2. Prior to the activity, draw a big illustration of a sample Tree Map on a manila paper. Refer to Teacher Resource Sheet 9, Sample Tree Map, page 42.
3. Group the students into four.
4. Provide each group with a manila paper, marker and masking tape. 5. Let them draw the tree map on the manila paper provided.
6. In their tree map, let the students think of a product they want to produce/invent to improve their health or improve something in their home/society. Let them write the name of the product in the upper box. Below the upper box are three small boxes where each box corresponds to a certain task. The first task is for them to think of the processes involved in the production of their product. Second task is for them to identify the changes (physical and chemical changes) involved in the process. And the third task is for them to explain how this product could improve the quality of human life.
7. When done, let them post and present their work.
Activity 5.3: Changing Banana!
1. This is a practical work wherein you have an option to let the students do this at home. 2. But if you choose to do this in school, let them work by three's and inform them a day
before that they should bring unripe banana and baking soda.
3. On the day of the activity, let them place a banana on a shelf at room temperature. Dissolve a spoonful of baking soda in a cup of water, and seal the cup and another banana in a sealable bag. After two days, let them check their bananas. As a class discussion, ask this question; Which ripens first? Why?
5. You may want to have a review on the factors that affects the rate of chemical reaction.
Formative Assessment
Performance rubric will be used to assess students' performance.
Roundup
The students should have applied their learning through the practical activity performed in this stage; identified the changes(physical or chemical) involved during the process of production.
6. Closure
This stage brings the series of lessons to a formal conclusion. Teachers may refocus the objectives and summarize the learning gained. Teachers can also foreshadow the next set of learning experiences and make the relevant links.
Background or purpose
Now that they are already equipped with knowledge on the changes of matter and its application in the society, they can now express their understanding of the topic.
Strategy
3-2-1 Journal is a strategy where students will write : 3 key terms from what they have just learned, 2 ideas they would like to learn more about, and 1 concept or skill they think they have just mastered.
Materials
Student Activity Sheet 6, Three-Two-One, page 43
Activity 6: Three-Two-One
1. Divide the students into groups of four.
2. Distribute Student Activity Sheet 6, Three-Two-One, page 43.
3. Instruct them to write three key terms and its definition from what they have just learned, two ideas they would like to learn more about, and one concept or skill they think they have just mastered.
4. Let them present their work.
Formative Assessment
Check the concepts written on their journal.
Roundup
Teacher Evaluation
(To be completed by the teacher using this Teacher’s Guide) The ways I will evaluate the success of my teaching this unit are: 1.
Student Activity Sheet 1
Mix 'N Match
PAPER
SCISSORS
SALT
WATER
MILK
VINEGAR
WOOD
FIRE
PAPER
MATCHES
Teacher Resource Sheet
Vinegar Making
Vinegar
is an alcoholic liquid that has been allowed to sour. It is primarily used to
flavor and preserve foods and as an ingredient in salad dressings and marinades.
Vinegar is also used as a cleaning agent. The word is from the French
vin
(wine)
and
aigre
(sour).
The world's oldest cooking ingredient may just be vinegar. According to The Vinegar
Institute, vinegar's history can be traced back over 10,000 years.
Vinegar is the result of a conversion by bacteria of alcoholic solutions in acetic
acid.
Coconut vinegar,made from fermented coconut
water, is used extensively in Southeast Asian
cuisine (particularly in the Philippines, a major
producer, where it is called suka ng niyog), as
well as in some cuisine of India. A cloudy white
liquid, it has a particularly sharp, acidic taste
with a slightly yeasty note.
Cane vinegar, made from sugar cane juice, is
most popular in the Philippines, in particular, the Ilocos Region of the northern
Philippines (where it is called sukang iloko), although it is produced in France and
the United States.
Production:
Vinegar is made from the oxidation of ethanol in wine, cider, beer, fermented fruit
juice, or nearly any other liquid containing alcohol. Commercial vinegars is
produced either by fast or slow fermentation processes. Slow methods are
generally used with traditional vinegars and fermentation proceeds slowly over the
course of weeks or months. The longer fermentation period allows for the
accumulation of a nontoxic slime composed of acetic acid bacteria and soluble
cellulose, known as the mother of vinegar.
Mother of Vinegar
A thick, gelatin substance containing bacteria that forms in vinegar most often
when the vinegar warms to temperatures between 60
0F to 85
0F. If present in
vinegar, the gummy Mother of Vinegar substance is not harmful and does not
indicate any spoilage in the vinegar solution. It has a natural occurrence that is
commonly used to assist the fermentation process when making wine or cider as
the bacteria turns the liquid into vinegar. The most notable bacteria that affects
the fermentation as Mother of Vinegar begins the process is known as Mycoderma
aceti.
http://en.wikipedia.org/wiki/Vinegar
http://www.madehow.com/Volume-7/Vinegar.html http://www.bellybytes.com/recipes/vinegar.shtml
Student Activity Sheet 3.1
It's A Matter Of Change
Procedure:
●
Read and perform the task being given in every station.
●
Wait for your teacher to give you the signal to move from one station to
another.
●
Fill in your data chart as you perform the task in each station.
Station Observations Type of Change (Chemical or Physical)
Evidence of Change
Station 1
Station 2
Station 3
Station 4
Station 5
Station 6
Teacher Resource Sheet 1
It's A Matter Of Change
These are instructions for the activity “It's A Matter Of Change” to be posted
in each station.
Also given here is the list of materials for the teacher to prepare and for each
group to bring.
Station Instructions:
Station 1- Baking Soda and Vinegar
Place some vinegar in a flask or coke bottle. Use the funnel to put some
baking soda into the balloon. Fasten the balloon over the mouth of the
flask or bottle. Lift the balloon up so that the baking soda falls into the
vinegar.
Station 2 – Alka-seltzer Rockets
Place an Alka – Seltzer tablet in a cup of water and observe the release of
carbon dioxide gas. Then, combine another tablet with some water in a
film canister, cap it tightly, step back at least one meter. Observe what
happens.
Station 3 – Cornstarch and Water
Mix approximately 35 grams cornstarch with 50 ml of water. Use your hand
to mix it. Squeeze the mixture in your hand. What happens? Now just hold
it in your hand. What happens?
Station 4 – Blowing Bubble
Place a semi - shallow plastic container on the table ( like one from a
margarine container). Pour 5 ml of bubble solution into it. Position a
drinking straw so that one end is in the bubble solution and touching the
lid. Gently blow air into the other end of the straw to make a large bubble
on the lid.
Station 5 – Disappearing Dye
Dip one cotton swab in food coloring and then stir it in the container of
water. What happens?
Dip the second cotton swab in food coloring and then stir it in the
container of bleach. What happens?
Continue to watch the container of bleach. What happens?
After five minutes, compare the two containers. What has happened?
Clean the petri dish for the next group to use.
Station 6 – Changing Sulfur
Heat the sulfur over the flame or hot plate. What begins to happen?
Continue heating. What happens?
Continue to add more heat to the sulfur and observe what happens.
Station 7 – Amazing Fruit
Cut the fruit (any o these choices; banana, apple, eggplant or potato) in
two sections. Put vitamin c on one section of the fruit.
Warning: NEVER PLAY WITH THE SHARP OBJECT
Observe for three minutes.
What happens to the two sections of the fruit after three minutes?
Experiments adapted from:
http://wow.osu.edu/experiments/chemistry/Chemical_and_Physical_Changes_R11
04.pdf
Teacher Resource Sheet 2
It's A Matter Of Change Answer Key
The answer key includes an explanation which could be used in the post laboratory
activity.
Station Observations Type of Change (Chemical or Physical)
Evidence for Change
Station 1 The balloon was inflated a bit.
Chemical Change The acetic acid from the vinegar and the baking soda, or sodium carbonate, react with with each other in an acid-base neutralization reaction.
The fizz that is observed is from the bubbles of carbon dioxide formed in the reaction.
Station 2 The lid of the film canister popped off.
Chemical Change Alka-seltzer is composed of sodium
bicarbonate and citric acid. When dissolved in water they react with each other to produce carbon dioxide and water. The carbon dioxide gas produced by the reaction builds up pressure in the closed fil canister, so much that eventually the lid can no longer fight the pressure, and is pushed off.
Station 3 When
squeezed, the mixture becomes more solid. It turned into a liquid matter when held in the hand.
Physical Change When mixed with water, cornstarch has properties not present when it is in powder form.
A mixture of cornstarch and water seems to behave like a liquid part of the time and like a solid part of the time. The surprising properties of this mixture are possible because cornstarch is made up of very long chains of molecules, or polymers. The polymers can move around and past each other, but they do so slowly. If poured slowly, the mixture will flow like a liquid. However if the mixture is forced to move more quickly than they can, they get so tangled up that they act more like a solid.
Station 4 Bubble is
Station 5 The water turns the color of the dye. At first the bleach colors slightly. Gradually the color
disappears and the color on the cotton swab also disappears.
Physical Change
Chemical Change
The water is colored, and the bleach is clear.
The dye is not gone. It has undergone a chemical change rendering it colorless.
Station 6 It first melts into a watery, straw colored liquid.
It now shifts to an orange color and then red color.
It becomes a slow flowing deep brown color. Continuous heating turns it brown, and it almost becomes solid and finally becomes liquid again.
Physical Change It change in color, shape and texture. But the end result was that the sulfur never really changed into anything else other than sulfur.
The color of an element such as sulfur depends on its temperature and also on the size of the unit mass of the element and the number of atoms in the molecule.
Station 7 One section of the fruit turned brown. But the section of the fruit with vitamin c retained its color.
Teacher Resource Sheet 3
Changes In Matter
Change in matter is the alteration in the form or composition of matter. It may be
of two types: physical or chemical.
A
Physical Change
is a change in matter that involves no chemical reaction. When
a substance undergoes a physical change, the composition of its molecules remains
unchanged and the substance does not lose its chemical identity. It is usually a
change which is reversible. By reversing the process, the original substance can be
obtained. Melting, evaporating, and freezing are three types of physical change.
For example, water is a liquid that freezes to form the solid ice, which may again
be melted into elements in the same proportions, the change from water to ice is a
physical change. Physical change includes any alteration in the shape and size of a
substance. For example cutting, grinding, crushing, annealing, dissolving, or
emulsifying produce physical changes. Still another physical change is sublimation,
the change from a solid to a gas.
Illustration 1: ice melting: is an example of physical change
A
Chemical Change
occurs whenever compounds are formed or decomposed.
During this reaction, there is rearrangement of atoms that makes or breaks
chemical bonds. This change is usually not reversible. In short, chemical change is
a change of one substance into another substance (i.e. A new substance is formed).
Chemical changes are happening very often. When wood burns it is a chemical
change. There are several different types of chemical change. These include
synthesis, decomposition, single displacement, double displacement,
neutralization, precipitation and redox.
An elementary example of a chemical change is the
combustion
of
methane
to
produce
carbon dioxide
and
water
:
Illustration 2: a nail rusting: an example of chemical change
Other examples of chemical changes are:
Burning a log of wood.
Mixing an acid with a base, producing water and a salt.
Photosynthesis, the food making process in plants in which carbon dioxide
and water are changed into sugars by plants.
Cracking heavy hydrocarbons to create lighter hydrocarbons (part of the
process of refining oil).
Cooking examples: popcorn, cake and eggs
oxidation examples: rust or tarnishing
The following can indicate that a chemical change took place, although this
evidence is not conclusive:
Change of color (for example, silver to reddish-brown when iron rusts).
Change in temperature or energy, such as the production (endothermic) or
loss (endothermic) of heat.
Change of form (for example, burning paper).
Light, heat, or sound is given off.
Formation of gases, often appearing as bubbles.
Formation of precipitate (insoluble particles).
The decomposition of organic matter (for example, rotting food).
Source:
Wikipedia, the free encyclopedia
http://www.encarta.msn.com
Student Activity Sheet 3.2.a
What's My Use?
Lipsticks
Most cosmetic products are mixtures of two or more liquids (e.g.
Perfumes), two or more solids (e.g powder, or a combination of liquids
and solids (e.g. Lipsticks). Mixing ingredients together does not by itself,
create a new substance or substances. Because the original ingredients
retain their chemical properties.
Like perfumes and powders, lipsticks and glosses are simple mixtures.
The ingredients used depend on the specifc properties they are meant to
exhibit, such as shininess, texture, durability, and color.
Student Activity Sheet 3.2.b
What's My Use?
Ceramics
Different types of ceramics are produced in ceramics manufacturing
starting with a raw material, and then adding other elements to create
desired properties. After this, the materials is prepped in ceramic
manufacturing for forming by adding water or another additive. The
resulting unfred ceramic material is known as greenware. Finally, the
object is fred in a kiln to become a rigid product, which can then be
glazed or further processed by polishing, cutting or machining for
advanced ceramics.
Ceramic products are usually divided into these sectors:
•
Structural, including bricks, pipes, foor and roof tiles.
•
Technical, is also known as Engineering, Advanced, Special and
Student Activity Sheet 3.2.c
What's My Use?
Fireworks
A frework is a device that uses combustion or explosion to produce a visual
and auditory effect.
Firecrackers consists of gunpowder wrapped in paper, with a fuse. The
materials will react with each other when enough heat is applied. Lighting the
fuse supplies the heat to light a frecracker. The charcoal or sugar is the fuel.
Potassium nitrate is the oxidizer, and sulfur moderates the reaction. Carbon
(from the charcoal or sugar) plus oxygen (from the air and potassium
nitrate) forms carbon dioxide and energy. Potassium nitrate, sulfur, and
carbon react to form nitrogen and carbon dioxide gases and potassium
sulfde. The pressure from the expanding nitrogen and carbon dioxide
explode the paper wrapper of a frecracker. The loud bang is the pop of the
wrapper being blown apart.
A frework is classifed as a low explosive pyrotechnic device used primarily
for aesthetic and entertainment purposes. Fireworks can also be used in
Student Activity Sheet 3.2.d
What's My Use?
Since most disease – causing organisms require a moist environment in which
to survive and multiply, drying is a natural technique for preventing spoilage.
Indeed, the act of simply leaving foods out in the sun and wind to dry is
probably one of the earliest forms of food preservation. Evidence for the
drying of meats, fsh, fruits and vegetables go back to the earliest recorded
human history.
Student Activity Sheet 3.2.e
What's My Use?
A glow stick is a single-use translucent plastic tube containing
isolated substances (hydrogen peroxide solution and a solution
containing a phenyl oxalate ester and a fuorescent dye) which when
combined are capable of producing light. Here's the sequence of
events when the two solutions are combined.
, ) The hydrogen peroxide oxidizes the phenyl oxalate ester, resulting in a
chemical called phenol and an unstable peroxyacid ester.
-) The unstable peroxyacid ester decomposes, resulting in additional
phenol and a cyclic peroxy compound.
. ) The cyclic peroxy compound decomposes to carbon dioxide. This
decomposition releases energy to the dye.
4) The electrons in the dye atoms jump to a higher level, then fall back down,
releasing energy in the form of light.
Glow sticks are used for many purposes. They are used as light
markers by military forces, campers and recreational divers. These are
also considered the only safe light source immediately after
earthquakes, hurricane and tornado and other emergency situations
because they do not use electricity to work and there is no danger of
Sources:
http://www.teachersdomain.org/resource/lsps07.sci.phys.matter.dfmakeup/
http://www.iqsdirectory.com/ceramic-manufacturing/
http://chemistry.about.com/od/howthingswork/a/fireworks.htm
http://en.wikipedia.org/wiki/Glowsticks
Student Activity Sheet 3.3
Heat in Chemical Reaction
A. Exothermic Reaction
Materials:
500 ml beaker, thermometer, powdered bleach, water
Procedure:
1) Fill the beaker half full of water. Dip the thermometer into the water. Let it
stay there for 2 minutes. What is the temperature of the water?
2) Add one tablespoon of powdered bleach. Take the temperature reading.
What happens?
3) You have just observed an exothermic reaction. In your own words, define
exothermic reaction.
B. Endothermic Reaction
Materials:
250 ml beaker, water, thermometer, ammonium nitrate
Procedure:
1) Pour 100 ml of water into the beaker. Dip the thermometer into the water.
What is the temperature?
2) Dump 15 grams (one level tablespoon) of ammonium nitrate into the water
all at once. Take the temperature reading. Describe what happens.
Student Activity Sheet 3.4.1
Fizzy Balloon
Materials:
a bowl of ice water
beaker of hot water
A balloon large enough to fit over a one-holed rubber stopper that has been
inserted into a 125 ml Erlenmeyer flask
one-holed rubber stopper
Alka-Seltzer tablets (approximately 3-5)
mortar and pestle
graduated cylinder
Procedure:
1.
Everyone must use 50 ml of water in their Erlenmeyer flask.
2.
Given the materials, think of a way to make the Alka-Seltzer react the
fastest at a given time frame and have the largest volume of balloon.
3.
The timing will begin from the time the Alka-Seltzer enters the flask and last
for exactly two minutes.
4.
At the end of the two minutes the balloon must be pinched off from the
flask and tied. ( A representative from the other group should be an observer
so people don't blow into their balloon to increase its volume.)
Student Activity Sheet 3.4.2
Fizzy Fun
A. The Effects of Temperature on the Rate of Reaction
Materials:
6 clear cups, measuring cup, thermometer ( -20
oC to 110
oC), graph paper
3 Alka – Seltzer tablets, stopwatch, mortar and pestle, hot water, ice cubes
Procedure:
A. Hot Water
1) Run water from the hot tap until it is as hot as possible. Fill a clear glass
with exactly 8 oz. of hot water.
2) Use the thermometer to take the temperature and record it on your data
sheet.
3) Remove 1 Alka-Seltzer tablet from its package. Drop it into the water.
Measure the time required for the tablet to fully dissolve. Be prepared to
start and stop on time. The reaction will take in less than 15 seconds. Record
the time.
B. Tap Water
1) Fill a clear glass with exactly 8 oz. of tap water.
2) Use the thermometer to take the temperature and record it on your data
sheet.
3) Drop 1 Alka-Seltzer tablet into the water. Measure the time required for the
reaction to be completed. Record the time.
C. Cold Water
1) Fill a clear glass with 4 oz of water and add enough ice to make it 8 oz. Stir
the iced water for about 15 seconds.
2) Take the temperature and record it on your data sheet. (Leave the ice cubes
in the water)
3) Drop 1 Alka-Seltzer tablet into the water. Measure the time required for the
reaction to be completed. Record the time.
Data Sheet
Water Temperature (0C) Time (sec)
Hot Water
Tap Water
Cold Water
Student Activity Sheet 3.4.3
Fizzy Fun
B. The Effect of Particle Size on Rate of Reaction
Materials:
3 clear glasses
3 Alka-Seltzer tablets
mortar and pestle
stopwatch
Procedure:
A. Whole Tablet
1) Fill a clear glass with exactly 8 oz of tap water.
2) Drop 1 whole Alka-Seltzer tablet into the water. Measure and record the
time to dissolve.
B. Tablet Broken into 8 pieces
1) Place 1 Alka-Seltzer tablet onto a sheet of paper and break into
approximately 8 pieces of about equal size.
2) Fill a clear glass with exactly 8 oz. of tap water.
3) Slide broken tablet into the water from the sheet. Measure and record the
time to dissolve.
C. Powdered Tablet
1) Place 1 Alka-Seltzer tablet into mortar and grind to a fine powder.
2) Transfer powder into a clear glass.(Note: It's important to have the powder
in the glass before adding water.
3) Add 8 oz of water to the glass. Measure and record the time to dissolve.
Date Sheet
Tablet Time
Whole Tablet
Broken into 8 pieces
Powder
Student Activity Sheet 3.4.4
Fizzy Fun
C. Effect of Pressure on the Rate of Chemical Reaction
Materials:
safety goggles, test tube 16x150 mm, cork stopper, 2 Alka-Seltzer tablets
baking soda, vinegar
Procedure:
A. Rate of Reaction at Normal Pressure
1) Fill a 16x150 mm test tube ½ full of water. The water should be at about
room temperature.
2) Break an Alka-Seltzer tablet in half and drop the pieces into the test tube.
3) Measure the time required for the reaction to be completed. Record the
time.
B. Rate of Reaction Under Increased Pressure
Put On Your Safety Goggles
1) Fill the 16x150 mm test tube ½ full of tap water.
2) Break an Alka-Seltzer tablet in half and drop the pieces into the test tube.
3) Immediately insert the cork stopper to the test tube to slow down the
escape of carbon dioxide gas. The pressure being exerted upon the reactants
inside the test tube is equal to the pressure you feel being exerted against a
cork.
Note: Do not try to stop all of the gas from escaping! If you try to do so, the
test tube will break. Just slow down the escaping gas as pressure builds up
inside of the test tube. That pressure acts upon the surface of the liquid.
The liquid moves in a direction that will relieve the pressure. The only
direction, without breaking the test tube, is upward and out. Avoid a total
“blow-out” of the liquid from the test tube by releasing enough pressure on
the cork from time to time to let gas and liquid “squeeze” its way past the
cork, in controlled amounts. This is a struggle, you against the gas pressure.
4) When gas bubbles are no longer visible in the liquid contained in the test
tube, consider the reaction to be over. Observe and record the time of the
reaction.
5) Release the pressure on the cork. Note that the reaction starts again.
Increase pressure on the cork and the reaction stops.
the test tube. As a result, the reaction stops. When you release the
pressure, the reaction is able to start again.
Student Activity Sheet 3.4.5
Fizzy Fun
D. Effect of Catalyst in the Rate of Chemical Reaction
Materials:
safety goggles
two 250-ml Erlenmeyer flasks
two hot plates
100 ml of distilled water
two 3.2 g samples of powdered copper
two 0.6 g samples powdered sulfur
100 ml of copper (II) sulfate solution
Procedure:
1.
With your safety goggles on, pour 100 ml of distilled water into one of the
flasks.
2.
Boil the water on the hot plate.
3.
Mix a sample of powdered copper and powdered sulfur together and stir the
powder mixture into the distilled water.
4.
Observe the results. Record your observations in your laboratory journal.
5.
Pour 100 ml of the copper (II) sulfate solution into the second flask.
6.
Slowly boil the solution on the hot plate.
7.
Mix a sample of powdered copper and powdered sulfur together, and stir the
powder mix into the copper (II) sulfate solution.
Questions:
1.
Explain what happened in the first flask.
2.
Explain what happened in the second flask.
Teacher Resource Sheet 5
Rate of Chemical Reaction
A
chemical reaction
is a process that always results in the interconversion of
chemical substances. The substance or substances initially involved in a chemical
reaction are called reactants. Chemical reactions are
usually characterized by a chemical change, and they
yield one or more products, which usually have
properties different from the reactants.
Chemical reactions are very important part of the food
we eat. The energy in all of our food can be traced to
photosynthesis, a chemical reaction that occurs in
plants. Ripening of fruits and vegetables involves many
chemical reactions, many
of them with oxygen as a
reactant. And the preservatives and flavorings in food
are all based on chemical reactions.
Understanding how fast chemical reactions happen is
important. For example, food chemists must know
how long a preservative is able to preserve a certain
food. The
reaction rate
is a measure of how rapidly a
reaction takes place. It is calculated by figuring out the amount or reactants that
remain after certain period of time.
Reaction rates vary widely. Some (such as burning) happen rapidly; others (such as
rusting) may take years. To understand the speed of chemical reaction, it is
necessary to understand the two condition that must exist before a reaction can
take place. First, the reactants particles must come in contact with each other.
Second, this contact must occur in such a way that a various particles can bond
with each other. Thus, changing the conditions can change the speed with which
the reactants contact each other and form a chemical bond. In other words,
changing the conditions can change the reaction rate. Five factors affect reaction
rates.
•
Temperature.
Often the easiest way to change the reaction rate is by
•
Surface Area.
Increasing the surface area (amount of exposed surface) of a
solid reactant increases the reaction rate. A reactant crushed or ground into
smaller fragments has more exposed surface area than one larger piece.
When more surface area is exposed, particles of the reactants come in
contact and bond with each other more frequently. For example, solid zinc
reacts with hydrochloric acid to form zinc chloride and hydrogen gas. Cubes
of zinc measuring a centimeter on each side have only 6 cm
2of zinc surface
area exposed to the acid. But grinding the zinc into powder exposes 10,000
times more surface area to the acid. The larger surface area greatly speeds
up the reaction rate.
•
Concentration of Reactants.
The reaction rate generally increases when the
concentration of the reactants is increased. This is because there are more
particles available to bond and the particles collide more often. For
example, substances such as coal burn much more rapidly in pure oxygen
than in air because air is composed of only 20 percent oxygen. Since the
combustion (burning) reaction requires oxygen, extra oxygen increases the
speed of the reaction. But sometimes increasing the concentration of a
reactant does not increase the reaction rate. Chemical reactions frequently
take place in a series of simple steps called a reaction pathway. The slowest
reaction along this pathway, called the rate determining step, determines
the speed of the entire reaction pathway. Adding more of a reactant to one
of the other pathway steps will not speed up the overall reaction. Picture
the rate determining step this way. Imagine you and your friends are making
sandwiches for a fund raiser. Three people are spreading mustard on the
bread, three people are putting meat and cheese on the bread, and one
person is wrapping the sandwiches in plastic wrap. Wrapping takes a long
time, and only one person is wrapping. So the person who is wrapping
determines the pace of the sandwich making. In other words, wrapping the
sandwiches is the determining step. Recruiting more people to spread
mustard or put meat and cheese on the bread will not speed up the overall
sandwich making process.
•
Catalyst.
Some chemical reactions happen
quite slowly and require the presence of
another substance to speed up the reaction
rate. A substance that increases the
reaction rate without being permanently
changed is called a
catalyst
. A catalyst is
not part of the final product of a reaction.
Sometimes chemists can even recover and reuse catalysts. Catalysts are
common in the human body, usually in the form of enzymes, which are
proteins. Enzymes can speed up chemical reactions in the human body by a
factor of 10,000. For example, an enzyme in human saliva, acting as a
catalyst, speeds up the conversion of starch into glucose so it can be
digested immediately instead of several weeks later!
Student Activity Sheet 4.1
What A Day!
Procedure:
Read the story below. Encircle the physical changes and underline the
chemical changes you see within it.
Hmmm. A brand new day. You go into the the kitchen and open the
refrigerator and pour a glass of fresh milk. Before you can even
drink it you can tell from the smell that the milk has soured. You
make a glass of ice water instead. After a while you find your kitchen
is slowly being filled with smoke coming from the window. You peep
outside and see your neighbor burning their garbage in their
backyard. You run outside and accidentally stepped on a rusty tuck.
You run to the medicine cabinet and grab an antiseptic. As you are
walking back to the kitchen, you noticed that some of the fruits are
already decaying.
You go back to get your iced water but find that the ice has melted.
You are so thirsty you don't care and drink it anyway. You suddenly
realize how hungry you are and take an apple from the table and bite
it. Suddenly you hear glass breaking. You run to see what has
happened and find that a baseball hit your window. It came from
nowhere.
What a day! And it's only just begun. You go back to eat your apple,
but it has turned brown. You decide to make some eggs and toast
instead. You first whip the eggs with fork and then cook them. You
popped a piece of bread in the toaster, which later turns nice and
brown.
You think about dyeing your hair brown but then remember how your
parents reacted when your sister did that. So instead you just
Teacher Resource Sheet 7
Questions- Rate Chemical Reaction
For questions 1-4, have students state which factor affects the rate of the
following chemical reactions.
1.
A reaction will not occur in the gas supply to a Bunsen Burner if it is turned
on without a match.
2.
The grain dispersed in the air in a grain elevator will explode or burn if a
spark or flame is present.
3.
Hospital rooms have “NO SMOKING” signs in the rooms of patients who are
receiving extra oxygen.
4.
Starch would not give us energy if our bodies do not contain many different
enzymes to first break up the large starch molecules.
5.
How does an increase in temperature affect the reaction rate?
6.
What is a catalyst?
Teacher Resource Sheet 8
Answer Key – Rate Of Chemical Reaction
For questions 1-4, have students state which factor affects the rate of the
following chemical reactions.
1.
A reaction will not occur in the gas supply to a Bunsen Burner if it is turned
on without a match.
Temperature
2.
The grain dispersed in the air in a grain elevator will explode or burn if a
spark or flame is present.
Surface Area
3.
Hospital rooms have “NO SMOKING” signs in the rooms of patients who are
receiving extra oxygen.
Concentration of Reactant
4.
Starch would not give us energy if our bodies do not contain many different
enzymes to first break up the large starch molecules.
Catalyst
5.
How does an increase in temperature affect the reaction rate?
The reaction rate is generally increased because heat causes the particles to
move faster, creating more collisions.
6.
What is a catalyst?
A substance that increases the rate of reaction without being permanently
changed.
7.
Name the five factors that affect the rate of chemical reaction.
Teacher Resource Sheet 9
Sample Tree Map
Product you want to
produce/invent
Processes
involved:
Changes involved:
How the product
could improve the
Student Activity Sheet 6
Three-Two-One
Procedure:
Write three key terms from what you have just learned in the first column,
two ideas you would like to learn more about in the second column, and one
concept or skill you have mastered in the third column.
What you have learned Ideas you want to learn more about
For the Teacher:
Translate the information in this Learning Guide into the following matrix to help you prepare your lesson plans.
Stage
1.
Activating Prior
Learning
2.
Setting the
Context
3.
Learning
Activity Sequence
4.
Check for
Understanding
5.
Practice and
Application
6.
Closure
Strategies
Activities from the Learning Guide
Extra activities you may wish to include
Materials and planning needed
Estimated time for this Stage
