clo2+H2O2+OH-GIVESCLO2- +O2+H2O balance with in ion electron method
Answers
The reaction is :
Cl2O7 → ClO2-
Balance Cl :
Cl2O7 2ClO2-
balance the O by adding H2O to the side which has less O
Cl2O7 2ClO2^- + 3H2O
balance the H by adding H+ to the other side
Cl2O7 + 6H+ ---> 2ClO2^- + 3H2O
Now, this has used acid to this point. convet to basic by adding the same number of OH- as you have H+ to each side of the arrow
Cl2O7 + 6H+ + 6OH- ---> 2ClO2^- + 3H2O + 6OH-
where there is H+ and OH- on the same side you will get H2O
Cl2O7 + 6H2O ---> 2ClO2^- + 3H2O + 6OH-
cancel out H2O that occurs on both sides
Cl2O7 + 3H2O ---> 2ClO2^- + 6OH-
Now, we need to work out how many electrons are transferred. To do this add up the total charge on both sides of the arrow. Then add as many electrons as needed to baalnce the charge to the side that has the most positive charge
LHS = 2 x ClO2^- + 6 x OH- = 8-
RHS = no charge
add 8 e to the LHS
Cl2O7 + 3H2O + 8e ------------> 2ClO2^- + 6OH
this is the balanced oxidation half equation
Reduction half equation, follow the same method
H2O2 -----> O2
H2O2 ----> O2 + 2H+
H2O2 + 2OH- ---> O2 + 2H+ + 2OH-
H2O2 + 2OH- ---> O2 + 2H2O
H2O2 + 2OH- ---> O2 + 2H2O + 2e
balanced reduction half equation
Now, add the two together. But first, the oxidation half equation transfers 8 electrons, wheras the reduction half equation transfers only 2. So you need 4 x the reduction half equation to balance the oxidation half equation
4 x (H2O2 + 2OH- ---> O2 + 2H2O + 2e)
gives
4H2O2 + 8OH- ----> 4O2 + 8H2O + 8e
Now
Cl2O7 + 3H2O + 8e ------------> 2ClO2^- + 6OH-
4H2O2 + 8OH- -----> 4O2 + 8H2O + 8e
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Cl2O7 + 3H2O + 4H2O2 + 8OH- + 8e ---> 2ClO2^- + 6OH- + 4O2 + 8H2O + 8e
cancel out the electons and anything else that occurs on both sides.
Cl2O7 + 4H2O2 + 2OH- ---> 2ClO2^- + 4O2 + 5H2O
balanced equation