Mohr’s salt (ammoniumiron(II)sulfate) is a complex compound by the formula: (NH4)2SO4.FeSO4.6H2O.
During this experiment iron(II)-ions will react in acid environment with permanganate ions to form iron(III)-ions and manganese(II)-ions. To ensure the solution remains colourless, fosforic acid will be added to the solution. No indicator will be used during this titration, because an excess permanganate will colour the solution pink.
Chemical equation:
MnO4- + 5 Fe2+ + 8 H3O+ ------> Mn2+ + 5 Fe3+ + 12 H2O