# Lemon Battery

Introduction

Batteries convert chemical energy into electrical energy. They have two electrodes called a cathode and an anode where chemical reactions that either use or produce electrons take place. The electrodes are connected by a solution called an electrolyte, through which ions can move and complete an electrical circuit. To generate electrical energy, a battery relies on oxidation at the anode (releases electrons), and a reduction at the cathode (uses electrons). Potential difference, volts (V), is measured between the two electrodes (cathode – anode) with a voltmeter.

Materials

• 1.0M citric acid
• 2 sets alligator clips
• beaker
• metal strip, aluminum (Al)
• metal strip, copper (Cu)
• metal strip, iron (Fe)
• metal strip, lead (Pb)
• metal strip, tin (Sn)
• metal strip, zinc (Zn)
• multimeter with test leads

Procedures

1. Set the multimeter so that it is measuring DCV (direct current voltage), use the “20” setting. (read the number as a decimal)
2. Connect one end of an alligator clips to the red lead of the multimeter and the other end to the Al metal strip/electrode.
3. Connect one end of the second alligator clips to the black lead of the multimeter and the other end to the Cu metal strip/electrode.
4. Place the two (2) electrodes (metal strips) in the beaker with 100 mL of citric acid.
5. Measure the potential difference (voltage) between Al and Cu.
6. If the voltage is negative, switch the alligator clips on the electrodes.
7. Repeat experiment with different combinations of electrodes (metal strips).

Data

 aluminum (Al) copper (Cu) iron (Fe) lead (Pb) tin (Sn) measured expected measured expected measured expected measured expected measured expected copper (Cu) iron (Fe) lead (Pb) tin (Sn) zinc (Zn)

Analysis

1. Which combination gives the most voltage? ???
2. Which combination gives the least voltage? ???
3. Identify the reducing and oxidizing agent for each combination. ???
4. Calculate the expected voltage for each combination. (pg. 674) ???
5. Compare and explain the measured voltage with the expected voltage. ???
*Honors extension
6. Write the balanced voltaic cell reaction equation for each combination. ???

How to do this assignment?

Chemistry in March