for the reaction, determine the number of transferring electrons so then i can pug into G=-nFE

Question

I'm assigning charges to each of the elements

H2O2(aq) + 2ClO2(g) → O2(g) + 2HClO2(aq)
(+1,-1) + (+4,-2) (0) (+1,+1,-2)

since O changes from -1 to 0, so it lost one electron but Cl gains 3 electrons, so I'm confused is it a total of 3 electrons that are being transferred?

Answer 1

Check me out to see that I do this correctly.
H2O2 ==> O2 + 2H^+ + 2e
(Both O on left = -2 and zero on right so both O change by 2e. Atoms balance, charge balances, electron change balances.)
ClO2 + e + H^+ ==> HClO2
(Cl changes from +4 to +3 for 1e change. Atoms balance, electron change balances, charge balances )
Multiply equation 2 by 2 and add.

H2O2 + 2ClO2 + 2e + 2H^+ ==> O2 + 2H^+ + 2e + 2HClO2
(2e cancel, 2H^+ cancel, leaving
H2O2 + 2ClO2 ==>O2 + 2HClO2
So total change in electrons is 2.

The easier way is to look at the equation you started with of
H2O2 + 2ClO2 ==> 2HClO2 + O2

O2 in H2O2 is the only O changing so both O goes from -2 on left to zero on right for change of 2e.
Both Cl on left are +8 and both Cl on right are +6 making change of 2e.

Answer 2

i see thanks, this helps alot, so do i say that H2O2 is the reducing agent and ClO2 is the oxidizing agent or just oxygen and chlorin only

Answer 3

You can say oxygen in H2O2 is the reducing agent or that H2O2 is the reducing agent. ClO2 is the oxidizing agent.