Chemical Reactions & Electricity

Transcription

1 THE TEAK PROJECT: TRAVELING ENGINEERING ACTIVITY KITS Chemical Reactions & Electricity Partial support for this project was provided by the National Science Foundation's Course, Curriculum, and Laboratory Improvement (CCLI) program under Award No Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. Partial support for this project was provided by the American Society for Heating, Refrigeration, and Air-Conditioning Engineering (ASHRAE) through a Senior Projects grant. Any opinions findings and conclusions or recommendations expressed here are those of the author(s) and do not necessarily reflect the views of ASHRAE

2 TEAK Chemical Reactions & Electricity Lesson Plan Page 2 ACTIVITY OVERVIEW Chemical Reactions & Electricity Kit Overview Students who complete this kit will learn about chemistry, batteries, and using fruit to turn on the lights. Engineers are working on ways to improve the efficiency of batteries, such as those found in cell phones, laptops, and electric cars. They are also working to develop batteries that could be smaller than a human hair, designed for use in the medical and aerospace industries. This kit is designed to give students a better understanding of how chemical energy is used to create electrical energy, using the chemical energy stored fruit as an example. Activity Time Description Fruit Battery Activity 60 min This experiment demonstrates how chemical energy can be transformed into electrical energy, like a battery. Student teams will create their own fruit battery used to run a digital clock and experiment with different kinds of fruit (electrolytes). Learning Objectives By the end of this lesson, students should be able to Explain how energy can be transformed Recognize a chemical reaction Understand basic principles behind chemical energy Explain how batteries work NYS Learning Standards Standard 3: Matter is made up of particles whose properties determine the observable characteristics of matter and its reactivity. Observe and describe properties of materials using appropriate tools. Describe chemical and physical changes, including changes in states of matter. Standard 4: Energy exists in many forms, and when these forms change energy is conserved. Describe a variety of forms of energy (e.g., heat, chemical, light) and the changes that occur in objects when they interact with those forms of energy. Observe the way one form of energy can be transformed into another form of energy present in common situations (e.g., mechanical to heat energy, mechanical to electrical energy, chemical to heat energy).

3 TEAK Chemical Reactions & Electricity Lesson Plan Page 3 TABLE OF CONTENTS Instructor Preparation Guide... 4 Definitions... 4 Pointers for Chemical Reactions & Electricity Kit... 4 Additional Materials Required... 4 Chemical Reactions Activity Introduction... 6 Background Information... 6 Chemical Energy Group Discussion... 6 Learning Objectives... 7 Materials for Each Group... 7 Procedure... 8 Expected Results Activity Extenders Concluding Discussion Trouble-Shooting Guide Fruit Battery Activity Challenge 1: Fruit Energy Challenge 2: Fruit Battery Challenge 1 & 2 Answeres Image Sources Extended Resources Revisions Signifies Group Discussion Signifies Activity

4 TEAK Chemical Reactions & Electricity Lesson Plan Page 4 INSTRUCTOR PREPARATION GUIDE Definitions Chemical Reaction A process that transforms a substance into a new substance with a different chemical identity. A chemical reaction takes place when electrons are transferred between substances, thus forming and creating chemical bonds. When these bonds are broken or formed, stored energy is released. Chemical Energy The energy that is stored within the bonds of chemical compounds. Chemical energy is released during a chemical reaction. Pointers for Chemical Reactions & Electricity Kit 1. The orange bag is awesome and reusable for when you go get fruit. 2. You ll have to gauge how much the students already know about chemical energy and atoms. Some have not heard of atoms yet. It is usually easier to tell them what chemical energy is, rather than ask them. 3. Try to have a balance of questions and lecture too many questions can intimidate the students and too much lecture can be really boring. 4. Ask about chemical reactions they may already know and then give them examples to cover all of the examples of how you can tell a chemical reaction is occurring. 5. Use the slideshow to show them what is inside a battery (you can go to the link on the last slide to see what each part of the battery means). 6. If you have a computer hooked up, you can use an excel sheet to compare the data from Challenge 1 and find the average to see which fruit really did work the best (this is much faster than using the overhead). 7. If you do use the overhead, ask each group what their numbers were (if you let them come up to fill it out, it takes too long) Additional Materials Required Fruit o Lemon, Lime, Kiwi, Grapefruit, Orange, Potato Paper Towels

5 TEAK Chemical Reactions & Electricity Lesson Plan Page 5 Chemical Reactions & Electricity DURATION 60 Minutes CONCEPTS Energy Transformation Chemical Reactions Chemical Energy Batteries

6 TEAK Chemical Reactions & Electricity Lesson Plan Page 6 CHEMICAL REACTIONS ACTIVITY INTRODUCTION Background Information Chemical engineering is the application of chemistry in a scientific and technical atmosphere. Chemical engineers use their knowledge of chemistry to develop products from raw material and to devise ways to convert one material into another useful form. Due to their broad set of skills, chemical engineers are frequently referred to as universal engineers. Using principles of chemical reactions, chemical engineers are able to convert chemical energy into usable electrical energy. Chemical Energy Group Discussion (Pose the following questions to the group and let the discussion flow naturally try to give positive feedback to each child that contributes to the conversation.) Q: What are some forms of energy? Kinetic Potential Electrical Chemical Mechanical Heat/Thermal Electromagnetic Nuclear Q: What happens to energy when we use it? Energy is neither created nor destroyed The total amount of energy stays the same it only changes from one form to another. Q: Do you know what an electron is? It is the negatively charged subatomic particle that is found in a cloud around the center of an atom. Q: How do atoms combine? Atoms combine by sharing or lending electrons. This is called a chemical bond. Q: What is Chemical Energy? It is the energy stored in the bonds of atoms and molecules. A chemical reaction takes place when these bonds are broken or formed which releases the stored energy. Q: What are some ways you can tell a chemical reaction is occurring? Gives off heat instant heat pack Becomes colder instant cold pack A gas is produced baking soda and vinegar A solid is produced rust There is a color change Light is produced glow stick

7 TEAK Chemical Reactions & Electricity Lesson Plan Page 7 Q: Where is chemical energy found? Batteries chemical to electrical Gasoline chemical to mechanical/kinetic Digestion chemical to thermal/kinetic Burning chemical to thermal/light Rust chemical reaction: substance Q: How does a battery relate to chemical energy? Batteries are used to store chemical energy. When a battery is used, it is an example of converting chemical energy into electrical energy. Q: Have you ever wondered how a battery works or what s inside one? There are two metal plates or posts called electrodes which react with the acid in the battery. This results in a chemical reaction that produces electrons. When the two electrodes are connected by a wire, the electrons are able to move through it. This movement of electrons is known as electricity. Q: Have you ever seen the little number on a battery that has the letter V next to it? Do you know what the V stands for? Volts You can find out the number of volts a battery produces by using a multi-meter, which you ll do today Did you know when you mix zinc with the acid found in fruit, a chemical reaction occurs? A very small amount of hydrogen gas is produced. The acid found in fruit actually reacts with several kinds of metals. Using this knowledge, you are going to create your own battery out of fruit. Chemical Reactions & Electricity Activity 60 Minutes Learning Objectives By the end of this exercise, students should be able to Students should become aware that energy can be found in unexpected places. Students should learn the value of teamwork when doing experiments and finding solutions. Materials for Each Group 5 different pieces of fruit (Lemon, Lime, Kiwi, Grapefruit, Orange, Potato ) 7 Alligator Clips 1 Multi-meter 1 Clock Assembly 7 Copper Nails (positive charge) 7 Zinc Nails (negative charge) Paper Towels

8 TEAK Chemical Reactions & Electricity Lesson Plan Page 8 Procedure 1. Pass out a kit and an activity handout to each group. Tell them not to open the kit. 2. Read through the Challenge 1 questions on the top of the handout with the students. As a group, have them decide what they think and write down their answers on the lines for hypothesis. 3. Go over what they re responses are. Explain that the copper nail is the positive side of the battery and the zinc nail is the negative side of the battery. Tell the students that different kinds of fruit will be tested in the activities. a. It may be helpful to write down that copper=positive and zinc=negative on the board. 4. Instruct the students that the activities are going to be done step by step, and that all students should raise their hands when their group is done with a step. a. The instructor should walk around to each group while they are working and make sure that they have set up the activity/are using the multi-meter correctly. 5. It s important that the copper nail is connected to the positive side of the alarm clock. For the remainder of the procedure, roles will be defined in order to complete the activity. Below is a table that defines the responsibilities for each role. Students will assume a role throughout the remainder of the activity. Role Description Your main task is to carefully insert the nails into the fruit. If the nails are not CE Chemical Engineer inserted properly, the fruit battery will not work. You are also responsible for making sure the nails remain in the fruit throughout the experiment. Your main task is to connect the wires to the nails. If the wires are not connected EE Electrical Engineer properly, the fruit battery will not work. You are also responsible for making sure that the wires do not get tangled during the experiment. Your main task is to use the multi-meter to test the voltage produced by each fruit. TE Test Engineer You need to be careful not to move any of the nails or wires while taking your measurements. Your main task is to collect all the data gathered by your team. Using your best handwriting, you will need to write down all the data on the activity handout. DE Data Engineer Also, you will be responsible for interacting with other data engineers to compare voltages.

9 TEAK Chemical Reactions & Electricity Lesson Plan Page 9 ALL - Open the kit and take out the bag of engineering roles. Place them face down on the desk. (This can also be done by facilitator). Each student should take a role tag and read what their engineering job will be. CE - TE - Take out a piece of fruit, a zinc nail, and a copper nail. Put the nails into the fruit. Make sure that they are almost all the way in, but leave room for attaching wires to them. Take out the multi-meter, test probes, and laminated multi-meter card. Make sure that the leads are in the position shown on the card. Turn the dial to the 20V position. Place the red end of the multi-meter on the copper nail and the black end on the zinc nail. Read the voltage off the multi-meter display screen. **Remind the test engineers to hold the test probes by the plastic and not the metal ends. DE - Record the type of fruit and the voltage produced in the chart on the activity handout. **The CE, TE, and DE should repeat the previous 3 steps for the other 4 pieces of fruit** DE - Have all the DEs pair up to compare voltage data. They should record the data from the other teams in the second table on the handout. ALL - Answer the questions on the bottom of the handout. After everyone is finished, go over the questions/answers with the class. Have the students flip their handout over. Read the Challenge 2 question on the top of the handout with the students. As a group, have them decide what they think and write down their answer on the line for hypothesis. Go over what they re responses are. EE - EE - DE - EE - TE - DE - Take out 2 test leads and attach one to each wire coming out of the clock. Now attach the clip on the red wire to the copper nail and the clip on the black wire to the zinc nail. Did the clock light? If the clock didn t light, keep adding fruit until it does. Use the diagrams on the handout to help you connect the fruit correctly. Once the clock lights, stop adding fruit. In the table on the handout, write down the types of fruit used to light the clock in column 1. Then use the voltages you measured from Challenge 1 to fill out column 2. Add up the voltages. Disconnect the clock from the nails. Place the test probes of the multi-meter on the nails where the clock was attached. Read the voltage off the multi-meter display screen. Record the voltage on the activity handout under actual voltage. ALL - Answer the questions on the bottom of the handout. After everyone is finished, go over the questions/answers with the class.

10 TEAK Chemical Reactions & Electricity Lesson Plan Page 10 EE - CE - Unhook all wires from the fruit battery and put them back in the kit. Remove all nails from the fruit and put away. ALL - Make sure all parts are back in the kit container and hand the container to the instructor. End Chemical Reactions & Electriciy Activity Expected Results The students should come to realize that different kinds of fruit produce different voltages. They should find that it takes several pieces of fruit to start the clock. They should also come to the conclusion that fruit is not a good alternative to batteries. If groups try to set an alarm, it will not work. Explain that the alarm relies on current as well as voltage coming from the fruit, and the fruit can t produce enough current to set off the alarm. Activity Extenders Have the students form the largest chain of fruit they can. Attach the multi-meter so they can measure the total voltage and/or current.

11 TEAK Chemical Reactions & Electricity Lesson Plan Page 11 CONCLUDING DISCUSSION (Pick and choose depending on student questions/responses to activity) Q: Is a fruit battery a good alternative for batteries? Not really Each piece of fruit only produces a very small voltage. They also produce an extremely small current that will not work in most applications. To replace even a small battery you need several pieces of fruit which takes up a lot of space. If you tried to set the alarm during the activity, you would have noticed the fruit did not produce enough power for it to go off. The fruit also rots. Q: What does a fruit battery have to do with engineering? Engineers are researching how to improve batteries. They are trying to make the rechargeable batteries we use in things like cell phones, laptops, and electric cars last longer. They are also working on extremely small batteries (smaller than the width of a human hair) that can be used in the medical and aerospace industries. Engineers need to know the properties of materials they are working with. If you were an engineer designing and building a fruit juice processing facility, you really would not want to use any materials that are going to react to the fruit s acid. Q: What other types of fruit/food do you think would work in this activity? Lemon, Lime, Kiwi, Grapefruit, and/or Potato Q: What difficulties did you have constructing the fruit battery? Open ended question Q: Why do you think the fruit battery works? Zinc is an active metal and will react readily with acid found in fruit. A transfer of electrons takes place between the zinc and acid. o The zinc is oxidized (loss of an electron) and the acid is reduced (gain of an electron) to hydrogen gas. o This happens whether or not a copper nail is present. The copper nail helps draw power from the fruit and channel electrons through an external circuit. Q: What is the difference between zinc and copper that allows the fruit battery to work? Because of its atomic structure Zinc wants to give away 2 electrons and the copper wants to gain an extra electron. This imbalance creates electron flow, which creates electricity.

12 TEAK Chemical Reactions & Electricity Lesson Plan Page 12 TROUBLE-SHOOTING GUIDE Fruit Battery Activity Problem: Unable to light the alarm clock. Solution: Check that enough voltage is being generated by the circuit (~1.5 V) using the multi-meter. Try putting the zinc and copper nails closer to one another. Ensure the copper nail is attached to the (+) red wire and the zinc nail is attached to the black (-) negative wire. Try pushing the zinc and copper nails into the flesh of the fruit, as opposed to the rind. Try adding one more piece of fruit and/or squeezing the fruit. Try moving the wires coming from the clock. Try a different clock assembly. Push the nails into the fruit, and then pull them out a little so that the juices are on the nails when the multi-meter or alligator clips are connected Problem: Unable to produce more than 0.5 V Solution: Ensure the pieces of fruit are connected in series. Ensure that each zinc nail is connected to a copper nail.

13 Name(s) Group # TEAK Chemical Reactions & Electricity Lesson Plan Page 13 CHALLENGE 1: FRUIT ENERGY Observation: Zinc will chemically react with acid found in fruit (producing hydrogen gas). Questions: Can a battery be created using fruit, zinc and copper? Does the kind of fruit matter? If it does, which kind of fruit would work the best? What is your hypothesis? (What is your best guess?) Test your hypothesis: Place one zinc nail and one copper nail in a piece of fruit. To test if there are any volts being produced, place the red end of the multi-meter on the copper nail and the black end on the zinc nail. Type of Fruit Voltage (V) Analyze the Results: Have one person from your group collect data from at least one other group. Then compare the results. Type of Fruit Voltage (V) Voltage (V) Voltage (V) Voltage (V) Voltage (V) Group 1 Group 2 Group 3 Group 4 Group 5 1. Energy is being stored in the fruit. 2. Which fruit produced the most voltage overall? 3. Did the same type of fruit always produce the same amount of voltage? Yes or No 4. What do you think could cause the same type of fruit to produce different amounts of voltage? 5. Can you think of any other kinds of fruit that would work?

14 Name(s) Group # TEAK Chemical Reactions & Electricity Lesson Plan Page 14 CHALLENGE 2: FRUIT BATTERY Observation: Fruit can be used to store chemical energy like a battery. Question: Can a fruit battery also be used to convert the stored chemical energy into electrical energy? What is your hypothesis? (What is your best guess?) Test your hypothesis: If fruit is going to be used as a battery, it needs to have a positive and negative side just like a normal battery. The copper nail is the positive (+) end and the zinc nail is the negative (-) end. Start by connecting one fruit to the clock to see if it lights. Keep adding one more fruit until it lights. Use the following diagrams as a guide. ***When connecting the fruit to the clock, the copper nail must be connected to the red wire and the zinc nail must be connected to the black wire*** More testing: Check to see how many volts it took to start the clock. Add the individual voltages for each fruit you used from what you found in Challenge 1. Now test the actual voltage by connecting the multi-meter instead of the clock in the above diagrams. Experiment with other fruit combinations if you have time. Type of fruit used to light the clock Estimated Voltage Measured Voltage from Challenge 1 Analyze the Results: + + Actual Voltage Total = 1. energy is being converted into energy. 2. How many pieces of fruit did you use to start the clock? 3. How many volts did it take to start the clock? Do they match? Yes No 4. Did more than one combination of fruit start the clock? 5. Do you think a fruit battery is a good alternative for a regular battery?

15 TEAK Chemical Reactions & Electricity Lesson Plan Page 15 CHALLENGE 1 & 2 ANSWERS Challenge 1: 1. Chemical energy is being stored in the fruit. 2. Which fruit produced the most voltage overall? Will be whatever they measured 3. Did the same type of fruit always produce the same amount of voltage? Yes or No 4. What do you think could cause the same type of fruit to produce different amounts of voltage? How far the nails are pushed in, how juicy the fruit is, has one been squeezed? 5. Can you think of any other kinds of fruit that would work? Pretty much any kind of fruit will work, however the more acidic the fruit the better it works Challenge 2: 1. Chemical energy is being converted into Electrical energy. 2. How many pieces of fruit did you use to start the clock? Will be whatever they used 3. How many volts did it take to start the clock? ~1.5V 4. Did more than one combination of fruit start the clock? Will be whatever they tested 5. Do you think a fruit battery is a good alternative for a regular battery? See Concluding Discussion

16 TEAK Chemical Reactions & Electricity Lesson Plan Page 16 IMAGE SOURCES [1] Lents. The Nature of Power JPEG file. EXTENDED RESOURCES NMSEA Curriculum Listing MadSci Network Teach Engineering Resources Exploring Science and Technology REVISIONS Date Changes Made Changes Made By 4/1/2013 Edited for grammar and syntax issues. Reorganized the format. Todd Jackson