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5. Crystals of copper sulfate are prepared by reacting copper oxide, a base, with dilute sulfuric acid - Edexcel - GCSE Chemistry Combined Science - Question 5 - 2023 - Paper 1
Question 5
5. Crystals of copper sulfate are prepared by reacting copper oxide, a base, with dilute sulfuric acid. (a) Name the other product of this reaction. (b) During the... show full transcript
Worked Solution & Example Answer:5. Crystals of copper sulfate are prepared by reacting copper oxide, a base, with dilute sulfuric acid - Edexcel - GCSE Chemistry Combined Science - Question 5 - 2023 - Paper 1
Step 1
Step 2
5(b) Explain how the student knows when to stop adding copper oxide.
Answer
The student knows to stop adding copper oxide when no more black powder remains in the solution after stirring. This indicates that all the sulfuric acid has reacted with the copper oxide, forming copper sulfate, and any additional copper oxide would not dissolve.
Step 3
Step 4
5(d) Describe how the arrangement and movement of the particles change as crystals are formed from a solution.
Answer
When crystals are formed from a solution, the particles that were previously free to move in the liquid become more closely packed together as the temperature decreases and the solution becomes saturated. They arrange in a specific lattice structure, and their movement becomes restricted, leading to solid crystal formation.
Step 5
5(e) Explain, in terms of electrons, whether the copper in copper oxide has been oxidised, has been reduced, or has not been oxidised or reduced.
Answer
In copper oxide (CuO), copper is in the +2 oxidation state. When it reacts to form copper sulfate (CuSO₄), the copper does not gain or lose electrons; therefore, it has not been oxidised or reduced. Its oxidation state remains consistent.
Step 6
5(f) Calculate the mass of copper sulfate dissolved in 0.300 dm³ of this solution.
Answer
To calculate the mass of copper sulfate (CuSO₄) dissolved in 0.300 dm³:
Given concentration = 39.875 g dm⁻³,
Mass = Concentration × Volume = 39.875 g dm⁻³ × 0.300 dm³ = 11.9625 g.
Therefore, the mass of copper sulfate dissolved is approximately 11.96 g.