Question 2

An aqueous solution contains a mixture of two different metal-aqua ions, chosen from $[Al(H2O)6]3+[\text{Al}(\text{H}_2\text{O})_6]^{3+}$ , $[Fe(H2O)6]3+[\text{Fe}(\text{H}_2\text{O})_6]^{3+}$ , $[Fe(H2O)6]2+[\text{Fe}(\text{H}_2\text{O})_6]^{2+}$ , and $[Cu(H2O)6]2+[\text{Cu}(\text{H}_2\text{O})_6]^{2+}$ .

To identify the ions, two tests are carried out on separate samples of the mixture:

Test 1: Addition of a small volume of aqueous sodium carbonate, $Na2CO3(aq)\text{Na}_2\text{CO}_3(\text{aq})$ , results in the formation of a white precipitate and a blue-green precipitate, accompanied by the evolution of a colourless gas.
Test 2: Addition of excess aqueous ammonia, $NH3(aq)\text{NH}_3(\text{aq})$ , results in a mixture containing a white precipitate suspended in a deep-blue solution.

Which two metal-aqua ions are present in the mixture?

$[Al(H2O)6]3+[\text{Al}(\text{H}_2\text{O})_6]^{3+}$ and $[Cu(H2O)6]2+[\text{Cu}(\text{H}_2\text{O})_6]^{2+}$

$[Fe(H2O)6]3+[\text{Fe}(\text{H}_2\text{O})_6]^{3+}$ and $[Cu(H2O)6]2+[\text{Cu}(\text{H}_2\text{O})_6]^{2+}$

$[Al(H2O)6]3+[\text{Al}(\text{H}_2\text{O})_6]^{3+}$ and $[Fe(H2O)6]2+[\text{Fe}(\text{H}_2\text{O})_6]^{2+}$

$[Fe(H2O)6]3+[\text{Fe}(\text{H}_2\text{O})_6]^{3+}$ and $[Fe(H2O)6]2+[\text{Fe}(\text{H}_2\text{O})_6]^{2+}$