Destroyer, balancing redox reaction

[SN1]

Cr2O7 2- + H+ + I- -----> Cr+3 + H2O + I3-

which coefficient would be needed to balance I- ?

the solution says

in Cr2O7 2- , chromium is reduced from +6 to +3 (I understand this part)

then it said
3I- ----> 2e + I3 -

was the iodide ion oxidized ? wtf? in the reactant the charge is -1 and the product also is -1 then how did they come up with 2 electrons being oxidized?

also are you supposed to multiply the number of atoms by the charge when comparing them to the reactant? I thought you only do this when you are figuring out that the charge of a compound must be zero or it must equal to the anion.

GOD I HATE THESE DESTROYER PROBLEMS.

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[premac]

Cr2O7 2- + H+ + I- -----> Cr+3 + H2O + I3-

which coefficient would be needed to balance I- ?

the solution says

in Cr2O7 2- , chromium is reduced from +6 to +3 (I understand this part)

then it said
3I- ----> 2e + I3 -

was the iodide ion oxidized ? wtf? in the reactant the charge is -1 and the product also is -1 then how did they come up with 2 electrons being oxidized?

also are you supposed to multiply the number of atoms by the charge when comparing them to the reactant? I thought you only do this when you are figuring out that the charge of a compound must be zero or it must equal to the anion.

GOD I HATE THESE DESTROYER PROBLEMS.

In the reactant side, 3I- has the charge of -3. I- has a charge of -1, and there are 3 of them. It's 3(-1) = -3. The product, however, just has -1 charge on I3, so you would need 2e- on the product side to balance it.

 

[SN1]

In the reactant side, 3I- has the charge of -3. I- has a charge of -1, and there are 3 of them. It's 3(-1) = -3. The product, however, just has -1 charge on I3, so you would need 2e- on the product side to balance it.

before you even put the 3 in front of the iodide of the reactant, aren't you supposed to see if it is reduced or oxidized? Based on the original question both of them have a negative one charge so wtf?

 

[SN1]

What I am trying to say is that BEFORE you even attempt to do anything, aren't you supposed to assign OXIDATION number on the product and reactant side? Looking at the problem don't both Iodide ions have -1 charge?

I have balanced many redox rxns but the **** is wrong with this one.

 

[SN1]

by the way the iodide on the product side is I3 with a negative 1 charge NOT an Iodide with negative 3 charge.

 

[premac]

Balancing the equation with electrons should be the LAST step.
First, you balance the coefficients of the ELEMENTS, then you add H2O to balance the amount of oxygen, followed by the balancing with H+.
You need to put 3 in front of the I- in order to match I3- (3 I's). Then, since you don't need to balance any oxygen, you simply balance the charge by adding electrons.
I hope this makes sense!

 

[SN1]

Balancing the equation with electrons should be the LAST step.
First, you balance the coefficients of the ELEMENTS, then you add H2O to balance the amount of oxygen, followed by the balancing with H+.
You need to put 3 in front of the I- in order to match I3- (3 I's). Then, since you don't need to balance any oxygen, you simply balance the charge by adding electrons.
I hope this makes sense!

Yeah. I just looked up some videos on youtube and your method is GOOD.

thanks.