Energy and the Environment Activities: Division II

Activity 1: Lemon Battery

Integration Notes:
This activity discusses scientific concepts occurring in batteries and opens the possibility of alternative models for power sources.

Learner Outcomes:
Students will:

• See how the movement of ions can create an electrical current.

Materials:

• 1 large fresh lemon
• 2 alligator clips or pieces of copper wire, 20-22 gauge
• 1 galvanometer or Multi meter
• Sandpaper
• 1 zinc strip, 8 cm by 2 cm
• 1 piece of copper wire, 5 cm, or a copper strip the same size as the zinc

Introduction:
This activity reinforces the concepts of electrodes and electrolytes as introduced in Phase 1.

Activity Instructions:
1. Take the lemon and roll it on the table. You want to make it as 'soft' as possible without breaking the skin. You want to release as much of the juice as possible.

2. Use sandpaper to scrape the surface of both the zinc and copper electrodes. This will help to eliminate oxidation on the surface of the metals.

3. Insert the copper and zinc electrodes into the lemon. Make certain that they are not touching.

4. Attach wires to the electrodes (copper and zinc) and to a voltmeter or galvanometer.

5. Vary the distance between the electrodes to determine the amount of electric current produced by this battery.

The Science Behind the Activity
The copper electrons react with the acids in the lemon to form copper ions. These ions interact with the zinc electrode and steal electrons, forming zinc ions. This chemical reaction produces slightly over a volt of electricity. As the electrons move through the circuit, a weak magnetic field is produced.

Extension Ideas

• Students can utilize a variety of fruits (citrus or other) to test results.
• Can you put one electrode in one lemon and another in a second lemon and then connect the two lemons with a copper wire and get the same results?
• Are there other metals that work as well as copper and zinc? Have students find out the difference between an electron donor and electron acceptor.

References
Hixson, B.K. Edison Etc. Wild Goose Publications. 1994.
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Activity 2: Electroplating

Integration Notes:
This activity shows that the electrolyte's purpose is to allow for the movement of ions in a solution. If ions are already in the solution, the acidity and basic nature of the solution is not important.

Learner Outcomes:
At the end of the activity the students should be able to:

• construct an electroplating device.
• describe chemical changes that involve the transfer of electrons.
• describe the procedures used and the reactions occurring during the electroplating of a metal.

Materials:

• 300 ml beaker
• 6 volt battery
• Alligator Clips
• Copper sulphate solution (CuSO4)
• Copper Strip
• Spoon
• A variety of other metals (optional)
• Silver nitrate (optional)

Introduction:
Students will perform an electroplating experiment. In this activity, the reversibility of electrochemistry will be seen as a current causes a chemical reaction to take place. The reaction will occur when a copper strip and a paper clip are placed in copper nitrate 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. The current will result in the movement of copper ions.

Activity Instructions:
1. Pour 150ml of the copper sulphate solution in a 300 ml beaker.

2. Place the spoon and the copper strip in the solution. Caution: the spoon and the copper strip should not touch.

3. Attach one alligator clip to the spoon (the metal being reduced). Attach one alligator clip to the copper strip (the metal being oxidized.) IMPORTANT: Connect the spoon to the negative terminal of the battery and the copper strip to the positive terminal.

4. Wait approximately five to seven minutes for a reaction. The students should observe the color of the solution.

5. Disconnect the alligator clips, remove the spoon and copper strip from solution, observe end of copper strip that was attached to alligator clip and discuss observations.

The Science Behind the Activity
Electroplating is an example of an oxidation-reduction reaction. Copper metal is taken out of solution and plates onto the spoon. Concepts students should comprehend are that oxidation is a loss of electrons, reduction a gain of electrons. The battery supplied the extra electrons.

The (Cu) ions in the solution, which have a charge of 2+, combine with the extra electrons on the object to be plated. The copper strip becomes oxidized (loses electrons) and the spoon becomes reduced (gains electrons).

The loss of Cu 2+ ions in solution (those that are being plated out onto the spoon) can be observed, since the solution will begin to lose its blue color over time. The blue tint is due to the copper ions in solution, so as they are taken out of solution and plated onto the spoon, the solution loses its blue tinge.

Extension Ideas
Students could experiment with other metals and solutions. A solution of silver nitrate may be used instead of copper. Try different metals and see the results (try using zinc, copper, stainless steel, lead, etc.)

Safety
Students should avoid ingestion of copper sulphate solution.
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Activity 3: Planting Batteries

Integration Notes:
This activity looks at the social and scientific problems of batteries and allows students to reflect on the Phase 1 activity Electricity in our Daily Lives.

Learner Outcome:
Students will examine the environmental impact of batteries on plant life utilizing qualitative and quantitative measurements.

Materials:

• A variety of electrolytes
• Plants
• Ruler
• Graduated cylinder
• Student worksheet

Introduction:
Batteries help us maintain the lifestyle to which we have become accustomed, but at what price? This power source has direct short term benefits, but we often fail to consider the long term problems associated with batteries. Students should consider: What chemicals are contained within them? How should they be disposed of? Do they have any adverse effects on the environment?

The electrolytes used in batteries are often strong acids that easily allow for the transfer of ions. It is not practical to perform hands-on activities with strong electrolytes, but utilizing safer materials such as lemon juice or vinegar can simulate their impact on the environment.

Activity Instructions:
1. Obtain small fast growing plants or grow your own with hearty and economical seeds (such as beans).

2. Have students create a journal where they can record plant data (height, volume of water used, physical description, date taken).(See step 6)

3. Review the purpose of electrolytes in batteries and discuss their physical characteristics. Students can research the different electrolytes used today. Have students discuss the possible environmental effects of the improper disposal of batteries.

4. Select a different electrolyte to test for each plant. 'Water' each plant with the chosen electrolyte and record the daily changes that the electrolyte has on the plant.

5. Remember to keep one plant as a control. Continue to water it normally so that it can be compared with the other electrolytes used.

6. For the planting batteries journal, have students create a page for each electrolyte, recording: a) Electrolyte used; dates checked; Quantitative Data (such as ML of solution added, Height of plant (cm)); Qualitative Data (such as description of the physical characteristics of the plant)

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