Chemistry · May / June 2022 · Paper 12 · Question 27

The steps for the preparation of a pure sample of sodium nitrate are listed. 1 Titrate with dilute nitric acid until the end-point is seen. 2 Evaporate to concentrate the solution. 3 Rinse out the conical flask. 4 Add indicator. 5 Pipette a known volume of aqueous sodium hydroxide into a conical flask. 6 Cool and filter to remove crystals. 7 Repeat using the same volumes of aqueous sodium hydroxide and dilute nitric acid but no indicator. Which order of steps is correct?

1. A1 → 7 → 5 → 4 → 2 → 6 → 3
2. B3 → 5 → 7 → 1 → 2 → 4 → 6
3. C4 → 1 → 3 → 5 → 2 → 6 → 7
4. D5 → 4 → 1 → 3 → 7 → 2 → 6

As printed in the paper