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Topic: Question -Balance - Re-dox  (Read 5133 times)

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Offline sinthreck

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Question -Balance - Re-dox
« on: October 15, 2010, 07:38:13 AM »
Quote
Ammonium metavanadate reacts with sulfur dioxide in acidic solution as follows (H+ ions and H2O were omitted from this equation):
x VO3- + y SO2  →  x VO2+ + y SO42-
The ratio x : y (Enter both stoichiometric coefficients)

I have 3 possible answers:
1) 2:1 (Answer Key)
2) 1:1 (People on yahoo answers - The question was asked over a year ago)
3) 2:3 (My calculated value)

My calculation:

SO2  + 2e- :rarrow:  SO42-   x 3
VO3- :rarrow: VO2+ +3e-  x 2

This equals:

3SO2  + 6e- :rarrow:  3SO42-   
2VO3- :rarrow: 2VO2+ +6e- 

Electrons cancel and you have:

2VO3- + 3SO2   :rarrow: 2VO2+ + 3SO42-

This is a ratio of 2:3

Please *delete me*


Offline sjb

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Re: Question -Balance - Re-dox
« Reply #1 on: October 15, 2010, 07:55:17 AM »
VO3-, or VO3-? The two are different beasts. One has 2 atoms, the other 4. Having said that, I can't see both VO3- and SO2 gaining oxygen unless you've missed out something - perhaps the acid is also involved in the reaction equation?

Offline sinthreck

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Re: Question -Balance - Re-dox
« Reply #2 on: October 15, 2010, 04:00:19 PM »
Hi, You're correct. I made a typo when stating the question. Unfortunately, I don't think I can edit my original post

The question should state the equation as follows:

Quote
x VO3- + y SO2  →  x VO2+ + y SO42-

My calculations were correct (at least no typos).

Offline sinthreck

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Re: Question -Balance - Re-dox
« Reply #3 on: October 15, 2010, 10:51:26 PM »
Actually, I have changed my answer now and I agree with the answer key

I added in the H+ and H2O and got the correct result.

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