A forensic investigator is analyzing two unlabeled containers, A and B, recovered from a disused laboratory.
The investigator conducts a series of chemical tests on solid A and an aqueous solution of B. The tests and observations are recorded in the table below:
| Test | Observation |
|---|---|
| Add solid A to deionised water and stir | The solid dissolves completely to form a colourless solution |
| Add universal indicator to the solution of A | The indicator solution turns blue/violet |
| Perform a flame test on solid A | A lilac flame is observed |
| Appearance of the aqueous solution of B | Colourless liquid |
| Add universal indicator to the solution of B | The indicator solution turns orange |
| Add a small piece of calcium metal to the solution of B | Effervescence is observed; the gas produced burns with a squeaky pop, and the calcium metal dissolves |
| Add a spatula measure of solid A to the solution of B | Rapid fizzing is observed; the gas produced turns limewater cloudy, and solid A dissolves completely |
Identify A and B, using the information in the table. Fully explain your reasoning by linking each test and observation to your chemical deductions.
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.
