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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
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 ex... show full transcript
Worked Solution & Example Answer: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
Explain how the student knows when to stop adding copper oxide.
Answer
The student can tell to stop adding copper oxide when the black powder no longer dissolves in the solution. This is indicated by the appearance of unreacted copper oxide at the bottom of the beaker, signaling that the sulfuric acid has reacted fully with the maximum amount of copper oxide it can, thus forming a saturated solution of copper sulfate.
Step 2
Step 3
Describe how the arrangement and movement of the particles change as crystals are formed from a solution.
Answer
As water evaporates from the aqueous solution, the concentration of copper sulfate increases until saturation is reached. The dissolved particles begin to come together and form a solid structure as they lose energy. The particles arrange themselves in a fixed, orderly pattern, resulting in crystal formation. During crystallization, the particles are less mobile compared to their state in solution, as they are held tightly in a regular arrangement within the crystal lattice.
Step 4
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 the reaction, copper in copper oxide (CuO) has been reduced. This occurs because copper (II) ions (Cu²⁺) in the oxide gain electrons to form elemental copper (Cu). The process of gaining electrons is referred to as reduction, while losing electrons would be oxidation.
Step 5
Calculate the mass of copper sulfate dissolved in 0.300 dm³ of this solution.
Answer
To calculate the mass of copper sulfate (CuSO₄) in the solution, use the equation:
Substituting the values:
Thus, the mass of copper sulfate dissolved in 0.300 dm³ of the solution is approximately 11.96 g.