ron(II) ions in solution are oxidized by the air to iron(III) ions.
The amounts of iron(II) and iron(III) ions in solution can be found by using titrations
with acidified potassium manganate(VII) which only reacts with the iron(II) ions.
portions of a solution A, containing a mixture of iron(II) and iron(III)
ions, were acidified and titrated with potassium manganate(VII) solution of
concentration 0.0195 mol
• The mean titre was 
• About 150 cm
of solution A was reacted with excess zinc, which reduced the
iron(III) ions to iron(II) ions. The excess zinc was filtered off.
portions of this reduced solution, which contained iron(II) ions but no
iron(III) ions were acidified and titrated with potassium manganate(VII) solution
of concentration 0.0195 mol dm
The mean titre was 18.20 cm
Calculate the mass of iron(II) ions and the mass of iron(III) ions in 500 cm
of the
original solution A.
