In: Chemistry
In each of the following balanced oxidation-reduction equations, identify those elements that undergo changes in oxidation number and indicate the magnitude of the change in each case.
2MnO4−(aq)+3S2−(aq)+4H2O(l)→3S(s)+2MnO2(s)+8OH−(aq)
4H2O2(aq)+Cl2O7(g)+2OH−(aq)→2ClO2−(aq)+5H2O(l)+4O2(g)
Ba2+(aq)+2OH−(aq)+H2O2(aq)+2ClO2(aq)→Ba(ClO2)2(s)+2H2O(l)+O2(g)
1)
Mn(+7)O(-2)4- + S(-2)2- + H(+1)2O(-2)
S(0)
+ Mn(+4)O(-2)2 + O(-2)H(+1)-
Oxidation
Thus, oxidation state of Sulphur changes from -2 to 0 (Magnitude of change = 2)
Reduction
Oxidation state of Manganese changes from +7 to +4 (Magnitude of change = 3)
2)
H(+1)2O(-1)2 +
Cl(+7)2O(-2)7 + O(-2)H(+1)-
Cl(+3)O(-2)2-
+ H(+1)2O(-2) + O(0)2
Oxidation
Thus, oxidation state of Oxygen changes from -1 to 0 (Magnitude of change = 1)
Reduction
Oxidation state of Chlorine changes from +7 to +3 (Magnitude of change = 4)
3)
Ba(+2)2+ + O(-2)H(+1)- +
H(+1)2O(-1)2 + Cl(+4)O(-2)2
Ba(+2)(Cl(+3)O(-2)2)2
+ H(+1)2O(-2) + O(0)2
Oxidation
Thus, oxidation state of Oxygen changes from -1 to 0 (Magnitude of change = 1)
Reduction
Oxidation state of Chlorine changes from +4 to +3 (Magnitude of change = 1)