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

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?

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.

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

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

To determine the number of transferring electrons in a reaction, you need to consider the changes in oxidation states of the elements involved.

In the given reaction:

H2O2(aq) + 2ClO2(g) → O2(g) + 2HClO2(aq)

We assign oxidation states to each element:

H2O2(aq): H = +1, O = -1
ClO2(g): Cl = +4, O = -2
O2(g): O = 0
HClO2(aq): H = +1, Cl = +1, O = -2

Looking at the changes in oxidation states, we can see that O in H2O2 goes from -1 to 0, which means it gains two electrons to become O2(g). This indicates that 2 electrons are gained by the O atoms.

On the other hand, Cl in ClO2 goes from +4 to +1, which means it gains three electrons to become HClO2. There are two Cl atoms involved, so each Cl atom gains three electrons.

Therefore, for this reaction, a total of 2 electrons are being transferred, with each Cl atom gaining 3 electrons and each O atom gaining 2 electrons.

Now, you can substitute the number of transferring electrons (n = 2) into the equation G = -nFE to calculate the standard Gibbs free energy change (G).