Under alkaline conditions , however , some of these reactions reverse ; for example , Mn2 + is oxidized to Mn4 + -LRB- as MnO2 -RRB- .

Under alkaline conditions , however , some of these reactions reverse ; Mn2 + is oxidized to Mn4 + -LRB- as MnO2 -RRB- , yet Fe3 + is reduced to Fe2 + .
