This laboratory used a piece of citrus fruit as a voltaic
cell to determine the relative positions of a series of different
metals in a series of electromotive forces by a qualitative
comparison. A quantitative comparison was also determined by
using voltages emitted by the various metals to calculate
1. The grapefruit was rolled between the hand and a hard surface to increase the electrolytes available in the solution of juice inside the fruit.
2. All the metal strips were cleaned by rubbing them briefly with fine emery paper to scratch them through the oxidized coating. The carbon rod was not cleaned.
3. Two parallel slits were made in the fruit, 2-4 cm apart, to insert the metals into without them touching each other.
4. The positive and negative leads were connected to the multimeter.
5. The multimeter switch was set to the V (volts) area of measurement.
1. The copper and magnesium strips were inserted into the fruit, making sure they did not come in contact with each other.
2. One lead was clipped to each of the metals.
3. If necessary, the leads were switched so that the multimeter read positive.
4. A record was made of which metal exhibited the greater reduction potential, and the numerical value for the volts generated was recorded in the data table.
5. One metal was removed and a new one inserted, and the procedure repeated.
6. This step was repeated until all possible pairs had been measured.
1. Ranking of relative reduction potentials for the metals used: