The ions present in ionic compounds can be identified using simple tests.
Table 1 shows the flame test colours for four cations.
Table 1
| Cation | Flame test colour |
|---|---|
| potassium | lilac |
| sodium | yellow |
| barium | green |
| boron | green |
Table 2 shows the results of three tests used to identify anions in solution.
Table 2
| Anion | Silver nitrate solution added | Barium chloride solution added | Limewater test |
|---|---|---|---|
| carbonate | white precipitate forms | white precipitate forms | turns cloudy |
| chloride | white precipitate forms | no change | no change |
| iodide | yellow precipitate forms | no change | no change |
| sulfate | no change | white precipitate forms | no change |
| sulfite | white precipitate forms | white precipitate forms | no change |
Use the information in the tables to answer these questions.
In the tests, compound A gives a lilac flame and produces no change when barium chloride solution is added.
Suggest two possible identities for compound A.
In the tests, compound B gives a green flame and produces a white precipitate when barium chloride solution is added.
A student concludes that compound B is barium carbonate.
Give two reasons why this conclusion may not be correct.
Which additional test from Table 2 would show whether the anion in compound B is carbonate or sulfite?
An aqueous solution contains either chloride ions or iodide ions.
Using only information from the tables, explain how you could decide if the solution contains chloride or iodide ions.
