The Daniell Cell

This demonstration shows how a Daniell cell generates electricity from chemical reactions between zinc and copper ions. A copper electrode in copper sulfate solution and a zinc electrode in zinc sulfate solution create a voltage that can be measured with a voltmeter or used to power a small device.

1. Fill one beaker with 1M copper sulfate solution and place a copper strip into it as the copper electrode.
2. Fill a second beaker with 1M zinc sulfate solution and place a zinc strip into it as the zinc electrode.
3. Prepare a salt bridge by soaking a strip of filter paper in a concentrated salt solution (such as potassium nitrate or sodium sulfate).
4. Place one end of the salt bridge into the copper sulfate beaker and the other end into the zinc sulfate beaker, ensuring good contact with the solutions.
5. Connect the copper and zinc electrodes with alligator clips.
6. Attach the clips to a digital voltmeter to measure the cell potential.

Electrochemical cell: The Daniell cell - C. Bettstetter:

📄 Daniell Cell - University of Washington: https://chem.washington.edu/lecture-demos/daniell-cell

• Replace the filter paper with a U-tube filled with salt solution as a salt bridge.
• Test different salt solutions in the bridge to see if the voltage output changes.
• Use alternative metals (such as iron or magnesium) and compare their voltages with copper.
• Connect the circuit to a small device (such as a piezo buzzer or LED) to demonstrate that the chemical reaction provides electrical energy.

• Wear safety goggles and gloves when handling copper sulfate and zinc sulfate solutions.
• Avoid skin contact with solutions.
• Dispose of solutions containing heavy metals properly according to hazardous waste regulations.
• Handle glass beakers and electrodes carefully to prevent breakage.

• Why is a salt bridge needed between the two beakers? (It completes the circuit by allowing ions to flow, maintaining charge balance.)
• What reaction occurs at the zinc electrode? (Zinc is oxidized to zinc ions, releasing electrons.)
• What reaction occurs at the copper electrode? (Copper ions are reduced and deposit as solid copper on the electrode.)
• How would the voltage change if you used a more reactive metal than zinc? (The voltage would increase because the difference in electrode potentials would be greater.)
• What role do electrons and ions play in maintaining the flow of current in the Daniell cell? (Electrons move through the wire, while ions migrate through the salt bridge to balance charges.)