Electrolysis of Copper Sulfate

Quantitative electrolysis with copper electrodes

Electrochemistry Intermediate (High School) 50 min ~$12.00

Objective

Perform quantitative electrolysis of copper sulfate solution using copper electrodes and verify Faraday's first law of electrolysis.

Background

When copper sulfate solution is electrolyzed with copper electrodes, copper is deposited at the cathode and dissolved from the anode. By measuring mass changes and current, Faraday's law can be verified: the mass of substance deposited is proportional to the charge passed.

Safety Warnings

  • Copper sulfate is toxic if ingested
  • Wear gloves when handling solutions
  • Handle electrical connections with dry hands

Required PPE

goggles gloves lab_coat

Materials

  • Copper(II) sulfate (CuSO₄) (200 mL)
    1M solution
  • Copper strips (2) (2 pieces)
    Similar size, sanded clean

Equipment

DC power supply (1-5V) Ammeter Beaker (400 mL) Wires Analytical balance Timer Sandpaper

Procedure

1

Sand both copper strips until shiny. Wash with distilled water and dry. Weigh each strip accurately on the analytical balance.

5 min
2

Pour 200 mL of 1M CuSO₄ into the beaker.

2 min Wear gloves
3

Connect the circuit: power supply → ammeter → anode (Cu strip) → solution → cathode (Cu strip) → power supply.

5 min
4

Set the power supply to give a steady current of about 0.5 A. Record the exact current.

2 min
5

Run the electrolysis for exactly 20 minutes, monitoring the current.

20 min
6

Turn off the power supply. Carefully remove both electrodes, rinse with distilled water, dry, and reweigh.

5 min
7

Calculate the charge passed (Q = I x t). Calculate theoretical mass deposited using Faraday's law: m = (M x Q) / (n x F). Compare with actual mass change.

8 min

Expected Results

The cathode should gain mass and the anode should lose approximately the same mass. At 0.5 A for 20 min: Q = 600 C, theoretical mass = (63.55 x 600) / (2 x 96485) = 0.197 g. Measured value should be within 10%.

Cleanup

Dispose of copper sulfate solution in heavy metal waste. Rinse and store copper strips. Clean the beaker and equipment.

Details

Category
Electrochemistry
Difficulty
Intermediate (High School)
Duration
50 min
Est. Cost
$12.00
Steps
7
Materials
2

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Frequently Asked Questions

What is the objective of Electrolysis of Copper Sulfate?
Perform quantitative electrolysis of copper sulfate solution using copper electrodes and verify Faraday's first law of electrolysis.
How difficult is Electrolysis of Copper Sulfate?
This experiment is rated as Intermediate (High School). It takes approximately 50 minutes to complete.
What safety precautions are needed for Electrolysis of Copper Sulfate?
Key safety precautions include: Copper sulfate is toxic if ingested; Wear gloves when handling solutions; Handle electrical connections with dry hands.
What materials are needed for Electrolysis of Copper Sulfate?
The main materials required are: Copper(II) sulfate (CuSO₄), Copper strips (2).
What results should I expect from Electrolysis of Copper Sulfate?
The cathode should gain mass and the anode should lose approximately the same mass. At 0.5 A for 20 min: Q = 600 C, theoretical mass = (63.55 x 600) / (2 x 96485) = 0.197 g. Measured value should be within 10%.