You will need to carry out the following steps and make and record appropriate observations. Use the table at the bottom to identify the oxidation state of vanadium.
Place 1 spatula measure of ammonium metavanadate(V) in a conical flask and add about 25 ml of dilute sulphuric acid. Carefully add about 5 cm3 of concentrated sulphuric acid and swirl the flask until you obtain a clear yellow solution of vanadium(V) solution.
Pour about 2 ml of this vanadium(V) solution into two test tubes ready for later tests (steps 6 and 7).
To the conical flask from step 1 add 1 spatula measure of zinc powder, a little at each time. Swirl the flask at intervals. Record.
When the solution has become violet (you may need to heat the flask for this final change), filter about 2 ml into two test tubes for steps 5 and 6.
To one test tube in step 4 add, a little each time, an excess of acidified potassium manganate(VII) solution, shaking after each addition, until no further change is observed. Record.
To one of the test tubes containing vanadium(V) (from step 2) add a little sodium sulphite and shake. Filter if cloudy. Now boil carefully (at a fume cupboard) to remove excess sulphur dioxide and add about the same volume of the vanadium(II) solution from step 4. Record.
To the second of the tubes containing vanadium(V) (from step 2), add about 2 ml potassium iodide solution and mix. Then add about 2 ml of sodium thiosulphate solution. Record.