Zinc Plated Penny Lesson Plan

Definitions

• Cation: A positively charged ion
• Oxidation: Loss of electrons
• Reduction: Gain of electrons
• Electrode: An electrical conductor that makes contact with the metallic part of a circuit. 
• Electrochemical Cell: A device that derives electrical energy from a chemical reaction (galvanic) or uses electrical energy to drive a chemical reaction (electrolytic)
• Galvanic Cell: Spontaneous chemical reactions take place at electrodes, converting chemical energy into electrical energy
• Electrolytic cell:  Electricity is used to drive a chemical reaction that does not occur spontaneously
• Electroplating: Uses electrical current to reduce dissolved metal cations so that they form a metal coating on an electrode.

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Materials

• 2 Clean  Pennies (You  can  clean  pennies  in  a  warm  water  bath  with  soap.  Use  a  brush  to  remove   major  deposits.  Then  rinse  with  vinegar)
• 250 mL  Beaker
• 20g  Zinc Sulfate (If  you  don't  have  zinc  sulfate  or  can't  make  it,  you  can  also  use  zinc  chloride.  This   can  be  made  by  simply  mixing  hydrochloric  acid  with  zinc  metal  and  waiting  until  the  fizzing   stops.)
• 3  Pieces  Solid  Zinc  Metal
• Hot  Plate
• Metal  Tongs
• 100  mL  beaker  filled  with  water
• Safety  Glasses and  gloves
• Metal  Tweezers
• Stop Watch

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Procedure

1. Weigh  each  penny (using  weigh  boat) and  record  the  weight  on  the  next  page.  Remember  to  keep   track  of  which  penny  is  what  weight.
2. EXPERIMENT  1-­‐ Place  250  mL  beaker  on  a  hot  plate
3. Add  two  pieces  of  solid  zinc  metal  (lay  horizontally  across  the  bottom  of  the  beaker)
4. Put  20  grams  of  Zinc  Sulfate  in  the  beaker
5. Pour  80 mL  of  water  into  the  beaker
6. Turn  hot  plate  on  and  bring  water  to  a  boil
7.  Once  boiling,  use  your  tweezers  to  place  penny  1  directly  on  top  of  the  zinc  metal  (the  penny  and   zinc  metal  must  be  touching  for  the  reaction  to  take  place)
8. Cover  the  250  mL  beaker  with  the  glass  cover
9. Wait  about  15  minutes  for  the  reaction  to  take  place
10. Once  you  have  observed  that  the  penny  changed  color  you  may  take  it  out  with  the  metal  tongs,   rinse  with  water,  dry  it  and  then place  it  in  the  weigh  boat
    1. Weigh and record penny 1's weight
    2. Describe the appearance of the penny
11. Before the next step, describe what you think will happen by placing your  zinc-­‐plated penny on a hot plate.
12. Using your  tongs , now  place  the  penny  directly  on  the  hot  plate  and  observe  what  happens
13. Once you observe a change, use your tongs to remove the penny from the hot plate and weigh and record its weight.  (Be  careful, the penny  will be HOT)
    1. Describe what happened when you placed the zinc-plated penny on the hot plate. Why do you think that this happened?
14. 14. Turn off your hot plate.
15. EXPERIMENT  2-­‐ For the next portion of the experiment, you will use the same solution that was prepared for the first part.
16. Connect one end of the red wire to the long zinc bar and the other end to the positive (+) terminal of the battery
17. Connect one end of the black wire to penny 2 and one end to the negative (-) terminal of the battery Once you have hooked them up, do not touch the ends together; keep your fingers on the plastic/rubber and not the metal
18. Place the long zinc bar in the solution
19. Place penny 2 in the solution while observing it very closely. Be careful to only submerge the penny and not the alligator clip.
20. Leave the penny submerged for 5 minutes.
21. After 3 minutes, take the penny out a. Weigh and record penny 2. b. Describe the appearance of the penny.