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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: /// on November 21, 2006, 06:45:19 PM

Title: Balancing EQN w/ Oxidation Number Method
Post by: /// on November 21, 2006, 06:45:19 PM
Can anyone tell me if this is right?

AuCl3(aq) + Cd(s) > Au(s) + CdCl2(aq)


I got to the step with the ratio question
There should be 3 Cd atoms when there are 2 Au atoms
So,

2AuCl3(aq) + 3Cd(s) > Au(s) + CdCl2(aq)

2AuCl3(aq) + 3Cd(s) > 2Au(s) + 3CdCl2(aq)

Is that all right?

Also, the ratio thing was sort of confusing.
I found that the difference in electrons for Au was 3, and the diff for Cd was 2, so then do I reverse the numbers and then it should be that there must be 3 Cd atoms for every 2 Au atoms?

Confusing:/
Title: Re: Balancing EQN w/ Oxidation Number Method
Post by: Borek on November 21, 2006, 07:12:10 PM
Quote from: lankan_ice_405 on November 21, 2006, 06:45:19 PM
2AuCl3(aq) + 3Cd(s) > 2Au(s) + 3CdCl2(aq)

Just check if it is balanced - same number of atoms, same charge - so it must be OK :)

Quote
I found that the difference in electrons for Au was 3, and the diff for Cd was 2, so then do I reverse the numbers and then it should be that there must be 3 Cd atoms for every 2 Au atoms?

More or less that works, but don't treat it is a general method. For example 4:2 won't give correct result (remember that coefiicients have to be the lowest possible).
Title: Re: Balancing EQN w/ Oxidation Number Method
Post by: /// on November 21, 2006, 07:41:56 PM
Thank you So much =)
Title: Re: Balancing EQN w/ Oxidation Number Method
Post by: /// on November 21, 2006, 09:44:52 PM
How about this one:

NaI + HClO > NaIO3 + HCl
(Balance using Oxidation NUmber Method)

I got

2NaI + 6HClO > 2NaIO3 + 6HCl
Which reduces down to

NaI + 3HClO > NaIO3 + 3HCl

Correct?
Title: Re: Balancing EQN w/ Oxidation Number Method
Post by: DevaDevil on November 21, 2006, 09:47:11 PM
Quote from: lankan_ice_405 on November 21, 2006, 09:44:52 PM
Correct?

Yes
Title: Re: Balancing EQN w/ Oxidation Number Method
Post by: MCylla on December 06, 2006, 03:35:25 PM
Okay....I am having the worst time in my chemistry class and we are currently balancing chemical equations.....and i am soo confused There are a few problems on this work sheet that she handed out to us and my brain is putting up the help i'm lost signal.....any and all help is greatly appreciated..


Sn + HF  Produce  SNF2 + H2

SiO2 + C produce   SiC2 + CO



 ??? Dez
Title: Re: Balancing EQN w/ Oxidation Number Method
Post by: Borek on December 06, 2006, 05:07:14 PM
Start assigning oxidation numbers to all elements.

Hint: assume Si is always +4.