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Excess dilute sulfuric acid is added to a solid sample of a copper compound - Edexcel - GCSE Chemistry - Question 4 - 2017 - Paper 1
Question 4
Excess dilute sulfuric acid is added to a solid sample of a copper compound. A gas is given off and a blue solution is formed. (i) The gas turns limewater cloudy. E... show full transcript
Worked Solution & Example Answer:Excess dilute sulfuric acid is added to a solid sample of a copper compound - Edexcel - GCSE Chemistry - Question 4 - 2017 - Paper 1
Step 1
Explain how this result is used to identify the anion in the copper compound.
Answer
The gas released during the reaction with dilute sulfuric acid is likely carbon dioxide (CO₂). When CO₂ is bubbled through limewater (a dilute solution of calcium hydroxide), it reacts to form calcium carbonate, which is insoluble and appears as a cloudy precipitate. Therefore, the resulting cloudiness of limewater indicates that carbonates are present in the original copper compound, confirming the presence of carbonate ions (CO₃²⁻).
Step 2
Step 3
Write the ionic equation, including state symbols, for this reaction.
Answer
The ionic equation for the reaction between barium chloride and sulfate ions is:
ightarrow ext{BaSO}_4(s)$$ In this equation, barium ions (Ba²⁺) and sulfate ions (SO₄²⁻) react to form solid barium sulfate (BaSO₄), which precipitates out of solution.