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This question is about ion testing - AQA - A-Level Chemistry - Question 8 - 2017 - Paper 1
Question 8
This question is about ion testing. 08.1 Describe how a student could distinguish between aqueous solutions of potassium nitrate, KNO₃, and potassium sulfate, K₂SO₄... show full transcript
Worked Solution & Example Answer:This question is about ion testing - AQA - A-Level Chemistry - Question 8 - 2017 - Paper 1
Step 1
Describe how a student could distinguish between aqueous solutions of potassium nitrate, KNO₃, and potassium sulfate, K₂SO₄, using one simple test-tube reaction.
Answer
Reagent: Sodium hydroxide (NaOH)
Observation with KNO₃(aq): Add NaOH to the KNO₃ solution. No visible change occurs; the solution remains colorless.
Observation with K₂SO₄(aq): Add NaOH to the K₂SO₄ solution. A white precipitate of barium sulfate (BaSO₄) will form if barium ions are present, indicating the presence of K₂SO₄.
Step 2
Describe how a student could distinguish between aqueous solutions of magnesium chloride, MgCl₂, and aluminium chloride, AlCl₃, using one simple test-tube reaction.
Answer
Reagent: Sodium hydroxide (NaOH)
Observation with MgCl₂(aq): When NaOH is added to the MgCl₂ solution, a white precipitate of magnesium hydroxide (Mg(OH)₂) forms, indicating that magnesium ions are present.
Observation with AlCl₃(aq): Upon adding NaOH to the AlCl₃ solution, a white precipitate of aluminium hydroxide (Al(OH)₃) will form, which may dissolve in excess NaOH, differentiating it from MgCl₂.