An analytical chemist investigates an unknown ionic compound, A, to identify the two different ions present.
The table below shows the tests performed and the corresponding observations.
| Test | Observation | |
|---|---|---|
| Test 1 | Flame test | Yellow flame |
| Test 2 | Dilute nitric acid and a few drops of silver nitrate solution are added to an aqueous solution of A | Yellow precipitate |
Use the results of Test 1 and Test 2 to write the chemical formula of compound A.
Another ionic compound, B, also consists of a single cation and a single anion.
The chemist adds a few drops of sodium hydroxide solution to an aqueous solution of compound B.
A white precipitate is observed to form.
Explain why this observation alone is insufficient to identify the cation present in compound B.
To test for the anion, the chemist adds some dilute hydrochloric acid followed by a few drops of silver nitrate solution to a fresh sample of compound B in solution.
A white precipitate forms.
The chemist concludes that the anion in compound B must be a chloride ion, Cl−\text{Cl}^-Cl−.
Explain why this conclusion is not definitive.
Describe how the chemist could modify the test in part (ii) to reliably confirm whether the anion in compound B is indeed a chloride ion, Cl−\text{Cl}^-Cl−.
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.