Liquid Battery

Project Number: 62

Description: Assemble the liquid energy source using the instructions on page 4. Connect the red & black jumper wires between the meter and the electrodes, the "+" side of the meter goes to the copper one. Set the meter to the 5V setting. Fill the compartments with cola soda (other flavors also work). The meter should show a voltage of 3V. Switch the meter to the 0.5mA to measure the current produced. Move the copper electrode with the snap on it over to the next compartment, as shown ("A"). Use the 5V setting to measure the voltage and the 0.5mA setting to measure the current. The voltage should only be about 3/4 of what it was, since you have one less component. The current should be about the same. Now move the copper electrode with the snap to the next component, so only two are used ("B"). See how the voltage drops even more, but the current changes little. Now move the copper electrode with the snap to the next compartment, so you only have one cola cell ("C"). Measure the voltage and the current now.

Snappy: Cola-flavored soda is lightly acidic. The acid is similar to the material used in types of batteries, but not as strong. The acid in the cola reacts with the copper and zinc electrodes to make electricity, just like a battery. As some of the acid in the soda is used up, the current produced drops. Each of the compartments in the liquid energy source produces about 0.75V, though the current is low. When the four compartments are connected in series, their voltages add together to make about 3V total, but the current is the same. Each compartment is like the cell of a battery. Your B4 rechargeable battery actually contains three 1.2V "cells" in series, just like the "cells" of the liquid energy source. Soda can be used in this way to produce electricity, but it does not produce very much, so it is not widely used. However, biomass power plants, which burn decaying food, products, and yard waste, are increasingly being used. These plants produce electricity from garbage that would otherwise be filling up landfills, and they don't pollute the environment.