Hydrated copper sulfate, CuSO₄·5H₂O, is a blue solid - Edexcel - GCSE Chemistry: Combined Science - Question 4 - 2019 - Paper 1

To demonstrate the reversibility of the reaction between hydrated copper sulfate and anhydrous copper sulfate, the following procedure can be followed:

Materials Needed:

• Hydrated copper sulfate (CuSO₄·5H₂O)
• A heating apparatus (Bunsen burner or hot plate)
• Heat-resistant test tube or beaker
• Anhydrous copper sulfate (CuSO₄)
• Water

Procedure:

1. Heating the Hydrated Copper Sulfate: Place a few crystals of hydrated copper sulfate in a heat-resistant test tube. Carefully heat the test tube using the Bunsen burner or hot plate. As the hydrated copper sulfate is heated, it will undergo a physical change, losing water molecules and turning into anhydrous copper sulfate, which appears as a white solid.

2. Observation: Record the color change as the blue hydrated copper sulfate turns white upon heating. This indicates the loss of water molecules.

3. Reversing the Reaction: To demonstrate that this is a reversible reaction, add a small amount of water to the anhydrous copper sulfate in a test tube. This will lead to the reformation of hydrated copper sulfate, which will turn the mixture back to blue.

4. Final Observation: Once water is added, observe the color change from white back to blue, confirming the reaction is reversible.

Conclusion:

By heating hydrated copper sulfate to produce anhydrous copper sulfate and then adding water to revert it back to its original form, the experiment clearly illustrates the reversibility of the process.