Complete and balance the following chemical equation :
MnO−4+H2O+I−→
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Solution
The complete, unbalanced chemical equation is :
MnO−4+H2O+I−→MnO2+IO−3
I atoms and Mn atoms are balanced. The oxidation number of iodine increases from −1 (in I−) to +5 (in IO−3). Total increase in oxidation number for iodine is +5−(−1)=6. The oxidation number of Mn decreases from +7 (in MnO−4) to +4 (in MnO2). Total decrease in oxidation number for Mn is 7−4=3. To balance the total increase in oxidation number with the total decrease in oxidation number, add coefficient 2 to Mn species.
2MnO−4+H2O+I−→2MnO2+IO−3
Balance O atoms by adding 2 water molecules to the products side.
2MnO−4+H2O+I−→2MnO2+IO−3+2H2O
One water molecule cancels on each side.
2MnO−4+I−→2MnO2+IO−3+H2O Balance H atoms by adding 2 protons to the reactants side.