Homework Help: Chemistry

Posted by Adeola on Sunday, June 13, 2010 at 2:38pm.

Balance the ewuation using thr oxidation number method

Here is what i did

Au+ + H20---> Au2O3 + Au + H+

Au+ losses 3e- to form Au2O3-->oxidation
Au+ gets reduced to for Au

therefore the balanced chemical equation is 3Au+ + 3H20---> Au2O3 +Au +6H+

Does it make sense?

Chemistry - DrBob222, Sunday, June 13, 2010 at 2:55pm
Yes and no.
The equation isn't balanced. (I know it looks balanced at first glance but it isn't.)
To be balanced, an equation must
1. have the same number of atoms on each side
2. have the same charge on each side.
3. electrons lost = electrons gained.
Your equation has 1 ok.
The charge doesn't balance (3+ on left and 6+ on right).
Electron change doesn't balance.

Here is the way I would do it.
Au^+ ==> Au2O3
First you make the Au atoms equal so we don't "split" charges.
2Au^+ ==> Au2O3
Oxidation state is +2 on left for 2 atoms and +6 on right for 2 atoms. We balance the change in state with electrons.
2Au^+ ==> Au2O3 + 4e
Count the charge on the left (+2) and right (-4) and balance with H^+.
2Au^+ ==> Au2O3 + 4e + 6H^+
Now add water to the other side to balance the H^+ added.
3H2O + 2Au^+ ==> Au2O3 + 4e + 6H^+

Next half cell.
Au^+ + e ==> Au

Now multiply the first equation by 1 and the second equation by 4 and add to obtain
3H2O + 6Au^+ ==> Au2O3 + 4Au + 6H^+
1. atoms balance 6H left and right. 3 O left and right. 6 Au left and right.
2. charge balances. +6 on left and right.
3.electron change balances. 2Au^+ on left move to Au2O3 where both Au atoms are +6. Loss of 4e. Other 4 Au^+ atoms move to 4Au on right. Gain of 4e.
Done.

Answer this Question

Related Questions

chemistry - Mg + Au+ -> Mg2+ + Au what is the oxidation and reduction ...
chemistry - Use the following steps to balance the redox reaction below: Mg + Au...
chemistry - write the oxidation and reduction half reactions for mg+au^+----&...
Chemistry - Au^3+ + 3e^- ---> Au Is this oxidation or reduction? Which ...
chemistry-balanced redox equations - Use the following steps to balance the ...
chemistry grade 12 - Question: Balance the following reactions by the oxidation ...
chemistry - Using the change-in-oxidation-number method, balance the redox ...
chemistry grade 12 - Question: Balance the following reactions by the oxidation ...
chemistry grade 12 - Question: Balance the following reactions by the oxidation ...
Chemistry - In which reaction does the oxidation number of oxygen increase? a. ...

For Further Reading

First Name:
School Subject:
Answer: