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Topic: Electronegativity N vs Cl  (Read 13790 times)

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Offline shalikadm

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Electronegativity N vs Cl
« on: December 02, 2012, 10:51:12 PM »
I've seen that we can't say which one is the most electronegative from Cl and N.I've seen that different scales gives different positions for N and Cl

And the one decimal Pauling scale given in our syllabus has N and Cl in the same position of 3.0

The question is whether NCl3 is a molecule having a center atom which has a negative oxidation number.

My tutor said:
Quote from: tutor
We can't say consistently which one is the most electronegative of N and Cl. We see it having the same place of 3.0 in Pauling scale. As Cl is a halogen we would say Cl is more electronegative than N.So in NCl3 N has a positive oxidation number and Cl has a negative one.


But according to Wikipedia it has a negative one and Cl has a positive one

Quote from: wikipedia
Despite the similarities of the Pauling electronegativities of nitrogen and chlorine, this molecule is very polar with negative charges residing on nitrogen. So the nitrogen in NCl3 is often considered to have the -3 oxidation state and the chlorine atoms are considered to be in the +1 oxidation state. Most of its reactivity is consistent with this description.

But I think that I must take what my tutor said.As he knows a lot about the paper we get.He knows what the idea of the professor about this who makes the exam paper.

But here's the hydrolysis of NCl3. It shows that N is more polar than Cl having a delta(-) residing on N.
Quote from: my book

And also I need to know whether the reaction of the hydrolysis of NCl3 is Redox or not ?
NCl3+3H2O :rarrow: 3HOCl+NH3
And also whether the oxidation number of Cl in HOCl is -1 or +1...
If its redox does N reduce from +3 to -3 and cl oxidize from -1 to +1 ?

Offline Hunter2

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Re: Electronegativity N vs Cl
« Reply #1 on: December 03, 2012, 01:29:30 AM »
Well Chlorine is more less equal to nitrogen, depending which scale is used, it is positive in NCl3 . In the hydrolysis there is no change in oxidation numbers.  In HOCl Chlorine is positive as well.

Offline Borek

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Re: Electronegativity N vs Cl
« Reply #2 on: December 03, 2012, 04:28:39 AM »
I don't like this question. Oxidation numbers don't have any real, measurable, physical property behind, they are just an artificial accounting device to keep track of electrons. Asking about "logic" behind border cases when the idea is lousy defined is a waste if time and only confuses students.

I would go with (N3+)(Cl-)3, but reality doesn't care about it.
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Offline shalikadm

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Re: Electronegativity N vs Cl
« Reply #3 on: December 04, 2012, 05:13:35 AM »
I would go with (N3+)(Cl-)3, but reality doesn't care about it.
According to your view, is hydrolysis of NCl3 a redox reaction?
As we see the oxidation number of N in NH3 is -3 and oxidation number of Cl in HOCl is +1 .
it is positive in NCl3 .
What you are saying is positive to wiki but negative to my tutor..
Who will I follow ?     :o

Offline Hunter2

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Re: Electronegativity N vs Cl
« Reply #4 on: December 04, 2012, 05:31:25 AM »
You follow your tutor to get a good grade.

Offline Borek

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Re: Electronegativity N vs Cl
« Reply #5 on: December 04, 2012, 10:43:48 AM »
According to your view, is hydrolysis of NCl3 a redox reaction?
As we see the oxidation number of N in NH3 is -3 and oxidation number of Cl in HOCl is +1

According to my view it doesn't matter. NCl3 doesn't care, it just reacts, regardless of how I classify the reaction.

Quote
What you are saying is positive to wiki but negative to my tutor..
Who will I follow ?     :o

As Hunter wrote - follow your tutor for the grade. Yes, it stinks. But it is not your fault that you are shown a grey paper and asked to classify it as white or black, without any intermediate possibilities. That's what happens when simplified ideas are forced onto real world.
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