July 09, 2020, 03:47:58 PM
Forum Rules: Read This Before Posting


Topic: NO and NO[sub]2[/sub] simple gas test  (Read 3804 times)

0 Members and 1 Guest are viewing this topic.

Offline zeoblade

  • Regular Member
  • ***
  • Posts: 88
  • Mole Snacks: +1/-0
NO and NO[sub]2[/sub] simple gas test
« on: February 25, 2010, 07:16:42 PM »
I'm trying to figure out simple gas tests for the presence of nitrogen dioxide (NO2) and nitric oxide (NO) but I can't find any.

NO2 is a characteristic dark red-brown gas and soluble in water so I am wondering if I can suck it up in a pipette and bubble it through water to convert into ions and change the dark red-brown colour and use pH indicator to test for an acidic environment. But would this discriminate from other gases that might do the same thing? Maybe using an alkene that won't react with nitrate to discriminate it from bromine?

For NO, I was thinking using the glowing split to combust NO into NO2 and then precede as per procedure above, does anyone know of a better and simple method?

Offline JGK

  • Chemist
  • Full Member
  • *
  • Posts: 738
  • Mole Snacks: +66/-19
  • Gender: Male
Experience is something you don't get until just after you need it.

Offline skyjumper

  • 1,3,7-trimethylxanthine
  • Full Member
  • ****
  • Posts: 167
  • Mole Snacks: +3/-4
  • Gender: Male
  • Lab Aid
Re: NO and NO[sub]2[/sub] simple gas test
« Reply #2 on: February 26, 2010, 02:28:57 PM »
You don't really need the splint. NO reacts readily with air to make NO2
per: 2 NO + O2 → 2 NO2

Offline zeoblade

  • Regular Member
  • ***
  • Posts: 88
  • Mole Snacks: +1/-0
Re: NO and NO[sub]2[/sub] simple gas test
« Reply #3 on: February 26, 2010, 08:45:37 PM »
For NO2 you could use fluorescein paper. Bromine will turn the paper pink, NO2 doesn't.

http://books.google.ca/books?id=_tsm4ZXmGdwC&pg=PA136&lpg=PA136&dq=fluorescein+paper&source=bl&ots=v-a_r_y8tV&sig=XUhkM8k8Y2HERIjsoleUynfWEXc&hl=xx-elmer&ei=oAGIS7CFGY-oNpX1nNIO&sa=X&oi=book_result&ct=result&resnum=4&ved=0CA8Q6AEwAzgK#v=onepage&q=fluorescein%20paper&f=false

I forgot about fluorescein, thanks

Quote
You don't really need the splint. NO reacts readily with air to make NO2 per: 2 NO + O2 → 2 NO2

Then I could use the colour of NO and NO2 to resolve them and test for NO2 as with fluorescein as JGK mentioned. Or maybe bubble NO2 through an alkene and add AgNO3 because if the dark re-brown gas was Br2 instead of NO2, AgBr would precipitate whereas adding NO2 to an alkene won't precipitate AgNO3. A bit more complicated than JGK's suggestion but I wonder if it's valid?

Offline zeoblade

  • Regular Member
  • ***
  • Posts: 88
  • Mole Snacks: +1/-0
Re: NO and NO[sub]2[/sub] simple gas test
« Reply #4 on: February 27, 2010, 01:57:19 AM »
I was also wondering how to distinguish between these acid pairs:

(a) Hydrobromic or hydroiodic acid

Bubble Cl2(g) through a solution of HI(aq) and will evolve I2(g), which is purple in colour but through a solution if HBr(aq) will evolve Br2(g) , which is brown in colour and will also layer above I2(g) because it’s molecular weight is lighter. Test the pH because HI will have a stronger degree of dissociation than HBr because of its electronegativity

(b) Sulfuric or nitric acid

NH3(g) + HNO3(aq) --> NH4NO3(s)
Bubble NH3(g) through HNO3(aq) will give NH4NO3(s), which is an explosive.

NH3(g) + H2SO4(aq) --> (NH4)2SO4(s)
But bubble NH3(g) though H2SO4(aq) will give (NH4)2SO4(s), which is a flame retardant.

(c) Hydrochloric or acetic acid?

HCl(aq) +  AgNO3(aq) --> AgCl2(s) + HNO3(aq)
Mix with AgNO3(aq) to precipitate a metal salt, AgCl2(s), that can be heated to produce silver metal and pale yellow-green chlorine gas.

CH3COOH(aq) + AgNO3(aq) --> CH3COOAg(s) + HNO3(aq)
Mixing with AgNO3(aq) to precipitate a metal acetate, CH3COOAg(s), that won’t produce metallic silver or a pale yellow-green gas when heated but will give an offensive taste in the presence of cigarette smoke.

Sponsored Links