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Author Topic: testing for nitrogen dioxide?  (Read 8572 times)

Offline tazzems

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testing for nitrogen dioxide?
« on: 04/10/2007 15:30:25 »
Hi

Can you help a couple of oldies lost trying to do chemistry homework please?

we need to make nitrogen dioxide, which we know how to do, so assuming we have 3 small glass containers of the gas how do we test it to prove that it is nitrogen dioxide?

Thanks in advance.
Emma and Dawn
xx


 

Offline tazzems

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testing for nitrogen dioxide?
« Reply #1 on: 04/10/2007 15:48:07 »
Also what should happen with either a lighted or glowing splint if we add it to the nitrogen dioxide?
 

Offline eric l

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testing for nitrogen dioxide?
« Reply #2 on: 04/10/2007 15:51:46 »
Two major indications :
  • the colour (reddish brown)
  • the smell ("biting" - but don't inhale too much as it is very toxic)

As for the second question :  I'm not sure at all.  NO2 is not as strong an oxidizing agent as concentrated nitric acid, and surely less oxydizing than pure oxygen.
« Last Edit: 04/10/2007 15:57:52 by eric l »
 

Offline tazzems

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testing for nitrogen dioxide?
« Reply #3 on: 04/10/2007 16:10:18 »
Thankyou very much hun.

we will be testing with blue litmus paper too, which should turn red.

We are assuming that limewater will turn cloudy?

 

Offline lightarrow

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testing for nitrogen dioxide?
« Reply #4 on: 04/10/2007 19:41:41 »
We are assuming that limewater will turn cloudy?
Not at all; on the contrary, if limewater is initially slightly cloudy, NO2 will make it more clear.

If you want to know how exactly it looks NO2, you only have to drop a copper coin in HNO3.
« Last Edit: 04/10/2007 19:46:57 by lightarrow »
 

Offline DrDick

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testing for nitrogen dioxide?
« Reply #5 on: 05/10/2007 20:54:45 »
You could try cooling the gas down.  Two brown NO2 molecules will combine to form one colorless N2O4 molecule.  Cool it in ice and you will get a less intense color.  Cool it more and the color will go away.

Elemental bromine also has a reddish-brown vapor.  If you cool that, however, in order to get rid of the color, you have to condense it into a brown liquid.

Dick
 

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testing for nitrogen dioxide?
« Reply #5 on: 05/10/2007 20:54:45 »

 

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