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Topic: Redox Half Reaction Method  (Read 14839 times)

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Offline theguy

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Redox Half Reaction Method
« on: February 20, 2012, 12:28:19 PM »
I'm having trouble balancing a redox equation.
Specifically the half reaction method.

The equation is NH3 + NO2-  :rarrow: N2 + H2O

No matter how many times I attempt this, I can never seem to get a reasonable answer.

« Last Edit: February 20, 2012, 12:57:18 PM by theguy »

Offline Borek

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Re: Redox Half Reaction Method
« Reply #1 on: February 20, 2012, 12:50:55 PM »
If there is no negative charge between products, you won't be able to balance this equation.

Are you sure it is not NH4NO2 decomposition?
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Offline theguy

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Re: Redox Half Reaction Method
« Reply #2 on: February 20, 2012, 12:56:19 PM »
Okay, I misread the equation. There is no negative charge. It was just a stray mark on my paper. Nonetheless, I've worked it without the negative and still can't get an answer that makes sense.

Offline Borek

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Re: Redox Half Reaction Method
« Reply #3 on: February 20, 2012, 01:22:21 PM »
Not every reaction can be balanced. What you wrote is one of these cases without an answer. Compare http://www.chembuddy.com/?left=balancing-stoichiometry&right=balancing-failure

As I suggested earlier, most likely it should be NH4NO2, not NH3NO2.
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Offline theguy

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Re: Redox Half Reaction Method
« Reply #4 on: February 20, 2012, 06:41:00 PM »
Not every reaction can be balanced. What you wrote is one of these cases without an answer. Compare http://www.chembuddy.com/?left=balancing-stoichiometry&right=balancing-failure

As I suggested earlier, most likely it should be NH4NO2, not NH3NO2.

The reactants aren't supposed to be combined. It's NH3 + NO2.

Offline Vidya

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Re: Redox Half Reaction Method
« Reply #5 on: February 20, 2012, 11:49:08 PM »
Ok
check these two balanced half reactions for the reaction given by you
2NH3---> N2 + 6e- + 6H+
8H+ + 6e- + 2NO2-    --------.> N2 + 4H2O
FINAL EQUATIONS IS
2NH3+ 2H+   +  2NO2-    ---> 2N2 +  4H2O

Offline Hunter2

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Re: Redox Half Reaction Method
« Reply #6 on: February 21, 2012, 01:02:51 AM »
No
FINAL EQUATIONS IS

NH3 + H+   +  NO2-    ---> N2 +  4 H2O

But above it was written there was no negative Charge on NO2

So the reduction would be

2 NO2 + 8 H+ + 8 e- => N2 + 4 H2O

8 NH3 => 4 N2 + 24 e- + 24 H+

6 NO2 + 24 H+ + 24 e- =>  3 N2 + 12 H2O

Final would be:

8 NH3 + 6 NO2  => 7 N2 + 12 H2O


Offline Vidya

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Re: Redox Half Reaction Method
« Reply #7 on: February 21, 2012, 01:06:13 AM »
No
FINAL EQUATIONS IS

NH3 + H+   +  NO2-   ---> N2 +  4 H2O

But above it was written there was no negative Charge on NO2

So the reduction would be

2 NO2 + 8 H+ + 8 e- => N2 + 4 H2O

8 NH3 => 4 N2 + 24 e- + 24 H+

6 NO2 + 24 H+ + 24 e- =>  3 N2 + 12 H2O

Final would be:

8 NH3 + 6 NO2  => 7 N2 + 12 H2O


I balanced this equation -
 NH3 + NO2- ----> N2 + H2O
in this equation NO2 has  -ve charge

Offline Hunter2

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Re: Redox Half Reaction Method
« Reply #8 on: February 21, 2012, 02:34:21 AM »
In the third post it was written:

Quote
Okay, I misread the equation. There is no negative charge. It was just a stray mark on my paper

Offline Borek

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Re: Redox Half Reaction Method
« Reply #9 on: February 21, 2012, 06:40:13 AM »
8 NH3 + 6 NO2  => 7 N2 + 12 H2O

Apparently I did something wrong before, as this is the correct answer.
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Offline neobenzene

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Re: Redox Half Reaction Method
« Reply #10 on: March 02, 2012, 01:23:17 AM »
I'm not sure if I'm right, but I got

8NH3 + 14NO2 + 32H+ -> 11N2 + 28H2O

Offline AWK

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Re: Redox Half Reaction Method
« Reply #11 on: March 02, 2012, 02:32:21 AM »
I'm not sure if I'm right, but I got

8NH3 + 14NO2 + 32H+ -> 11N2 + 28H2O
Charges are unbalances
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