$2\mathop {MnO_4^ - }\limits_1 + \mathop {5F{e^{2 + }}}\limits_5 + 8{H^ + } \to M{n^{2 + }} + 5F{e^{3 + }} + 4{H_2}O$
${H_2}O\,\, + \,\,\,B{r_2}\,\,\,\, \to \,\,\,HOBr\,\,\, + \,\,\,HBr$