Please help me... Please. Oxidation state in redox reaction.
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Please help me... Please. Oxidation state in redox reaction.

[From: ] [author: ] [Date: 11-10-10] [Hit: ]
Add out the 6e- on both sides,Add out 6H+ on both sides, leaving 8H+ on the left side.And I think thats it.......
balancing acidic redox reaction, the oxidation of ethanol by dichromate ion in acidic solution, producing chromium (III) ion, and acetaldehyde (CH3CHO) as products: The breathalyzer test!)

C2H5OH + Cr2O7^2- ---> Cr^3+ + CH3CHO

I've been going through this for an hour and I think my issue is I'm probably balancing the oxidation states in the beginning incorrectly. Please help me. Please...

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Start with the ethanol-ethanal reaction.
Balance the O's by adding water, balance the H's by adding H+, balance the charge by adding e- and you get:

C2H5OH ----> CH3CHO + 2H+ + 2e-

Then same thing with the dichromate reaction
[Cr2O7]2- + 14H+ + 6e- ----> 2Cr3- + 7H2O
(Charge balance: (2-) + (14+) + (6-) = 2x(3+)

The ethanol reaction produces 2e-; the dichromate reaction requires 6e- so the ethanol reaction gets multiplied by 3.

3C2H5OH + [Cr2O7]2- + 14H+ + 6e- ----> 3CH3CHO + 6H+ + 6e- + 2Cr3- + 7H2O
Add out the 6e- on both sides,
Add out 6H+ on both sides, leaving 8H+ on the left side.
And I think that's it.

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Simplify cant help if we cant understand
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