Standard Zinc/Copper Cell
A standard cell comprising zinc strip in 1.0 M ZnSO4 solution, a copper strip in a 1.0 M CuSO4 solution, and a connecting salt bridge are connected to a voltage probe. The voltage can be projected using the Vernier LabPro interface.
This is a great demo to introduce the concept of electrochemical cells. It can be preceded by the "Reaction of Zinc and Copper II Ion" demo to show how an electrochemical cell separates a redox reaction into reduction and oxidation half-reactions.
- 2 ea. 400 mL beakers, one containing a strip of zinc metal partially immersed in a 1.0 M ZnSO4 solution, the other containing a strip of copper metal partially immersed in a 1.0 M CuSO4 solution.
- a salt bridge comprising a u-tube filled with 1 M KNO3 solution. The ends of the u-tube should be tightly plugged with cotton that has been saturated in the KNO3 solution.
- a Vernier voltage probe.
- a Vernier "Go Link" interface.
- an empty 250 mL beaker to hold the salt bridge upright when not in use.
- a computer with the Vernier "Logger Lite" program that is capable of projecting the screen image.
- Place the two beakers side by side.
- Connect the probe leads to the metal strips where they stick up above the surface of the solutions.
- Place the salt bridge upside down so that one arm is in each of the solutions.
- Students should note that no voltage registers until the salt bridge is inserted into the solutions.
- Always wear goggles when performing chemistry demonstrations.
- Gloves should be worn to protect your hands from the solutions.