Summary

The reactions of transition metal ions in aqueous solution provide a practical opportunity for students to show and to understand how transition metal ions can be identified by test-tube reactions in the laboratory.

Specification

3.2.6 Reactions of ions in aqueous solution

In aqueous solution, the following metal-aqua ions are formed:

[M(H2O)6]2+, limited to M = Fe and Cu

[M(H2O)6]3+, limited to M = Al and Fe

The acidity of [M(H2O)6]3+ is greater than that of [M(H2O)6]2+

Some metal hydroxides show amphoteric character by dissolving in both acids and bases (e.g. hydroxides of Al3+).

Students should be able to:

• explain, in terms of the charge/size ratio of the metal ion, why the acidity of [M(H2O)6]3+ is greater than that of [M(H2O)6]2+

• describe and explain the simple test-tube reactions of:

M2+(aq) ions, limited to M = Fe and Cu, and of M3+(aq) ions, limited to M = Al and Fe, with the bases OH–, NH3 and CO32–

Required practical 11

Carry out simple test-tube reactions to identify transition metal ions in aqueous solution

Notes