A student analyses three unknown ionic compounds, A, B, and C, by performing two qualitative tests on aqueous solutions of each compound.
The student's observations and their subsequent conclusions are recorded in the table below:
| Ionic substance | Test 1 | Test 2 | Student's conclusion |
|---|---|---|---|
| A | white precipitate | brown precipitate | iron(III) chloride |
| B | yellow precipitate | white precipitate | calcium iodide |
| C | no precipitate | white precipitate which dissolves in excess sodium hydroxide | aluminium sulfate |
None of the student's conclusions are fully justified by these tests alone.
Explain which part of each conclusion is justified, why the remaining part is not fully justified, and describe the further experimental work required to fully confirm the identity of each substance.
Practise Edexcel GCSE Chemistry Qualitative analysis: tests for ions with exam-style questions for Foundation and Higher tier. 127 questions, matched to the Edexcel GCSE Chemistry (1CH0) specification and written in Paper 1 and Paper 2 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.
