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when iron(2) reacts with permanganate in acidic solution: in 3rd step why we mul

ID: 687132 • Letter: W

Question

when iron(2) reacts with permanganate in acidic solution: in 3rd step why we multiply oxidation halfreaction:{Fe(aq)____Fe(aq)+e}by 5. in 3rd step why we multiply oxidation halfreaction:{Fe(aq)____Fe(aq)+e}by 5.

Explanation / Answer

Reduction halfreaction:                                            MnO4--------->Mn2+                           oxidation no .of Mn in MnO4- is +7 oxidation no .of Mn in Mn2+ is +2 So change in Oxdn. no. is 5 So MnO4- +5e--------->Mn2+ Oxidation half reaction: Fe2+----------->Fe3+ Change in Oxdn. no. =1 So Fe2+ - e------------>Fe3+ But no of electrons lost in oxdn. = no of electrons gained inreduction So Oxdn. reaction is multiplied by 5 to give: 5Fe2+ - 5e------------>5Fe3+ MnO4- +5e--------->Mn2+ 5Fe2+ - 5e------------>5Fe3+ Net reaction is : MnO4- +5Fe2+------------>Mn2+ +5Fe3+