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Topic: Help with Oxidation Number Calculation  (Read 2880 times)

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Offline decapitatedomar

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Help with Oxidation Number Calculation
« on: October 25, 2012, 07:34:21 AM »
Hi, I've been facing some trouble with Oxidation Number, so I've got some questions to ask, as well as a problem I'd like to inquire about, here it goes;
1- When calculating the O.N, do you take in consideration the number of Moles? For instance, how would you calculate the O.N of Nitrogen in the following chemical formula: 2HNO3? Do you do (2*1 + N + 3*-2) or neglect the '2' in the beginning?

2- In which of the following reactions is Nitric acid an oxidizing agent:
4HNO3 + Cu ------> Cu(NO3)2 + 2H2O + 2NO2
or
2HNO3 + Na2CO3 ------> 2NaNO3 + H2O + CO2

And it would be much appreciated if you told me how you had calculated it. Hope that's not too much to ask. Thanks. :)



Offline Borek

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Re: Help with Oxidation Number Calculation
« Reply #1 on: October 25, 2012, 08:27:36 AM »
Hi, I've been facing some trouble with Oxidation Number, so I've got some questions to ask, as well as a problem I'd like to inquire about, here it goes;
1- When calculating the O.N, do you take in consideration the number of Moles? For instance, how would you calculate the O.N of Nitrogen in the following chemical formula: 2HNO3? Do you do (2*1 + N + 3*-2) or neglect the '2' in the beginning?

Oxidation number is a property of an atom in a single molecule, so the stoichiometric coefficient is irrelevant. Besides, what you wrote makes no sense - 2HNO3 means 2(HNO3), not 2H + NO3 what you seem to be suggesting.

Question 2 - assign oxidation numbers to nitrogen both before and after the reaction, it will answer your question.
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Offline decapitatedomar

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Re: Help with Oxidation Number Calculation
« Reply #2 on: October 25, 2012, 08:59:10 AM »
Hi, I've been facing some trouble with Oxidation Number, so I've got some questions to ask, as well as a problem I'd like to inquire about, here it goes;
1- When calculating the O.N, do you take in consideration the number of Moles? For instance, how would you calculate the O.N of Nitrogen in the following chemical formula: 2HNO3? Do you do (2*1 + N + 3*-2) or neglect the '2' in the beginning?

Oxidation number is a property of an atom in a single molecule, so the stoichiometric coefficient is irrelevant. Besides, what you wrote makes no sense - 2HNO3 means 2(HNO3), not 2H + NO3 what you seem to be suggesting.

Question 2 - assign oxidation numbers to nitrogen both before and after the reaction, it will answer your question.

Okay, thanks for pointing that out, but after the reaction, which compound should I be looking at? Because Nitrogen is in two compounds; 2NO2 and Cu(NO3)2. Thanks, and I'm sorry I'm taking up too much of your time.

Offline Borek

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Re: Help with Oxidation Number Calculation
« Reply #3 on: October 25, 2012, 09:45:19 AM »
Okay, thanks for pointing that out, but after the reaction, which compound should I be looking at? Because Nitrogen is in two compounds; 2NO2 and Cu(NO3)2.

Write net ionic reaction then.
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