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

Materials Required

• Hydrated copper sulfate (CuSO₄·5H₂O)
• Heating apparatus (Bunsen burner or hot plate)
• Heat-resistant container (e.g., crucible)
• Anhydrous copper sulfate (CuSO₄)
• Water
• Balance for measuring

Procedure

1. Measure and Heat: Measure a specific amount of hydrated copper sulfate (e.g., 5 grams) and place it in a heat-resistant container. Heat the container gently using a Bunsen burner or hot plate until the blue hydrated copper sulfate turns into a white anhydrous copper sulfate. This demonstrates the first part of the reversible reaction.

2. Cooling and Rehydrating: After obtaining the white anhydrous copper sulfate, allow it to cool. Once cooled, add a few drops of water to the container and observe the changes that occur. The white solid will gradually regain its blue color as it rehydrates, demonstrating that the reaction is indeed reversible.

Conclusion

By heating hydrated copper sulfate to remove water, it turns into anhydrous copper sulfate. Adding water back to anhydrous copper sulfate shows that it can revert to hydrated copper sulfate. This experiment clearly demonstrates the reversible nature of the reaction.