You are Here: Home

# electrode potentials question pls help watch

1. what is the answer to (ii)?

2. Which do you think it is? and why?
3. When two things react the one with the more negative (if they're both positive this means closest to 0) electrode potential will be the on that goes backwards and the other one will go forwards.
This means that if you want to oxidise chromium(II) to chromium(III) you want that reaction to go backwards so you want something less negative than -0.41.
In case you hadn't realised, the oxidation state of the chromium in (Cr2O7)2- is chromium(VI) and based on the questions you don't want this reaction to go backwards so you want something more negative than +1.33.
This means that you want something from the table with an electrode potential between -0.41 and +1.33 so the answer is iodine and bromine.
I'm very sorry if this is incorrect, I only wrapped my head around this topic myself very recently.
4. (Original post by Pigster)
Which do you think it is? and why?
I've figured it out. Thanks a lot!!
5. (Original post by LaM19)
When two things react the one with the more negative (if they're both positive this means closest to 0) electrode potential will be the on that goes backwards and the other one will go forwards.
This means that if you want to oxidise chromium(II) to chromium(III) you want that reaction to go backwards so you want something less negative than -0.41.
In case you hadn't realised, the oxidation state of the chromium in (Cr2O7)2- is chromium(VI) and based on the questions you don't want this reaction to go backwards so you want something more negative than +1.33.
This means that you want something from the table with an electrode potential between -0.41 and +1.33 so the answer is iodine and bromine.
I'm very sorry if this is incorrect, I only wrapped my head around this topic myself very recently.
Ahh thank you loads!! Yes you are correct.

### Related university courses

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: February 15, 2018
Today on TSR

### He lied about his age

Thought he was 19... really he's 14

### University open days

Wed, 25 Jul '18
2. University of Buckingham
Wed, 25 Jul '18
3. Bournemouth University