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 |
|---|---|
| caesium | blue |
| rubidium | violet |
| strontium | red |
| tantalum | blue |
Table 2 shows the results of three tests used to identify anions in solution.
Table 2
| Anion | Hydrochloric acid added | Magnesium chloride solution added | Methyl orange added |
|---|---|---|---|
| carbonate | effervescence | white precipitate forms | yellow |
| chloride | no change | no change | orange |
| hydrogencarbonate | effervescence | no change | yellow |
| hydrogensulfate | no change | no change | red |
| hydroxide | no change | white precipitate forms | yellow |
Use the information in the tables to answer these questions.
In the tests, compound A gives a violet flame and produces no change when magnesium chloride solution is added.
Suggest two possible identities for compound A.
In the tests, compound B gives a blue flame and produces a white precipitate when magnesium chloride solution is added.
A student concludes that compound B is caesium 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 hydroxide?
An aqueous solution contains either chloride ions or hydrogensulfate ions.
Using only information from the tables, explain how you could decide if the solution contains chloride or hydrogensulfate ions.
