A student investigates an ionic compound, A, to identify the two different ions in the compound.
The table shows the results of the tests that the student does.
| Test | Result | |
|---|---|---|
| Test 1 | flame test | lilac flame |
| Test 2 | dilute nitric acid and a few drops of silver nitrate solution are added to an aqueous solution of A | cream precipitate |
Use the results of tests 1 and 2 to write the formula of compound A.
Another ionic compound, B, also contains two ions.
The student adds a few drops of sodium hydroxide solution to a solution of compound B.
A white precipitate forms.
Explain why this result does not identify the cation in compound B.
The student adds some dilute sulfuric acid and a few drops of barium chloride solution to a fresh solution of compound B.
A white precipitate forms.
The student concludes that the anion in compound B is a sulfate ion, SO42−\text{SO}_4^{2-}SO42−.
Explain why the student cannot be certain that compound B contains sulfate ions.
Describe how the student could improve the test in part (ii) to confirm that the anion in compound B is a sulfate ion, SO42−\text{SO}_4^{2-}SO42−.
41 exam-style questions on OCR GCSE Chemistry Identifying the products of chemical reactions. Each one has a worked solution and a mark scheme showing where the marks go.