Bruce Kitsuse Peirce School
1423 W. Bryn Mawr Avenue
Chicago IL 60640
(312) 534-2440

Objectives: Students understand that electricity causes chemical reactions and chemical reactions can cause electricity. Materials needed: This list of materials is for three groups consisting of four members per group. 1. 1 Molar Copper Nitrate Solution 2. 1 Molar Zinc Nitrate Solution 3. 1 Molar Ammonium Nitrate Solution 4. 10 pieces of zinc metal 5. 10 pieces of copper metal 6. alligator clips 7. ten 300 ml glass beakers 8. masking tape 9. six stainless steel electrodes 10. box of epsom salt 11. six 6-volt batteries 12. insulated copper wire and wire stripper 13. six micro scale test tubes 14. matches and wood splints 15. paper clips 16. glass U-tube 17. cotton 18. voltmeter 19. buckets Strategy: Students will attain the objective by verifying the definition of electrochemical cell through experimentation in a quiet, calm atmosphere. Discipline will be achieved through a set of rules with consequences for misbehavior. The necessity of verification will be demonstrated through the use of newspaper and magazine articles which are subjective as opposed to factual. These articles will show that not everything we read is necessarily factual. It will set up the need to verify the definition of electrochemistry and electrochemical cell. "Electrochemical Cell" will be defined as an "apparatus that utilizes an electrolyte and electrodes in such a way that a chemical reaction will produce a current sent through an external circuit." Part of verifying the entire definition will be to define some of the words. Electrolyte is a liquid conductor that utilizes dissolved particles to conduct electricity. Students will make copper nitrate and zinc nitrate by combining measured amounts of copper nitrate and zinc nitrate crystals with water. Prior to combining, they will test the conductivity of the solid crystals with a voltmeter. After making an aqueous solution, they will test the conductivity of the solution. Students will return to their seats to discuss their observations. The electrolytic solutions will remain at their stations for use in further activities. Redox reaction will be defined as a gain and loss of electrons (oxidation and reduction). The example of table salt formed from the ionic transfer of electrons from sodium and chlorine will be used as an example of spontaneous gain and loss of electrons. Students will then verify that redox reactions exist by placing a strip of zinc metal into copper nitrate solution. They should observe the formation of copper and the corrosion of zinc metal. (Beakers of copper nitrate, alligator clips, and zinc strips will be passed out to three groups of four members each by teacher assistants. Discussion will occur in these groups. Discussion will focus in what redox reaction has occurred. The formula will be placed on the board before and during the activity. Students will be asked to explain the formula and their observations.) Students will then create a current by a redox chemical reaction by placing a zinc strip into zinc nitrate and a copper strip into copper nitrate. They will place one voltmeter electrode into the zinc nitrate solution and the other voltmeter electrode into the copper nitrate and note that no current was produced. A U-shaped tube will then connect the electrolytic solutions in the two beakers. The zinc and metal strips will be connected by alligator clips to the voltmeter and a current will flow. Overhead transparencies will be used to demonstrate the directions. The formula for the chemical reaction will be placed on board prior to and during the activity. At the end of 5 or 10 minutes, students will return to their seats and discuss their observations and explain the formula. Next, students will do electroplating. In this activity, the reversibility of electrochemistry will be seen because a current will cause a chemical reaction. The reaction will be that a copper strip is placed in copper nitrate solution and a paper clip is placed in the same solution. Both the copper strip and paper clip will be attached to wires which are hooked to the positive and negative electrodes of a battery (these instructions will be shown on an overhead projector.) The formula of the reaction will be shown prior to and during the activity. Students will be asked to explain both the formula and their observations upon completion of the activity. Finally, students will perform the electrolysis of water with a similar evaluation method. Performance Assessment: For most activities a formula of the expected reaction will be written on the overhead projector prior to and left there during the activity. The students comprehension of the activity will evaluated orally through their ability to explain both the formula and their observations. Conclusions: Students should understand that electricity can be produced by chemical reactions and chemical reactions can produce electricity because they have seen this happen in the activities they performed. They should also understand that in each case a redox reaction has occurred. Evaluation: Activities occurring in a science laboratory should be conducted under safe, calm conditions. The learning atmosphere will be evaluated and monitored constantly by the instructor. Movement of students from lab stations to normal seating will be especially scrutinized. A worksheet with written comprehension questions which should be filled out during the activities will help to assess student learning. Discussion of observations will provide the most direct information as to what was understood. References: Dorin, Chemistry, The Study of Matter, Allyn and Bacon

Williams, Chemistry Research Activities, Grolier Educational Corporation
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