Silver --> NO2

[encipher]

Hi,

 

I placed two silver disks in a beaker and added excess nitric acid to it, all of this was done in the balcony. I had my hot plate out there too. So i mix it and leave quickly and shut the balcony door. After the mixture heats up, a ton of NO2 gas starts evolving. After I while I started smelling it through the closed window, so I gather together two big fans, wait till the NO2 gas production has decreased, and open the balcony door. I aim the fans outside and turn them on full speed. Then i hold my breath and run out quickly (with a mask on of course) and turn off the hot plate. Now when I go back in I start breathing and the air was contaminated with NO2... I was breathing it in for like a minute. I quickly isolate the area, open all the windows.. shut all the doors to the area. Stop air conditioning and go into my room to write this. Now I held up the beaker to take a look at what was inside. All the silver had dissolved, the solution was a deep green color. I thought a solution of silver nitrate was supposed to be clear? Anyone have any idea on what the green color is? and wether I should probably see a doctor or not?

 

Thanks

[[w00t]]

nah could be impurities in the silver disks tho, how much no2 gas evolved exaclly.

no you dont need to see the doctor, did you actually feel the no2 gas go in?

 

i highly doubt there would be a large no2 gas forming being enough to kill you. only worry if you have your face over gas and breathing everything in.

 

but it wont hurt to go to the doctor, i breathed in no2 gas before. i feel better then ever.

[encipher]

Could there be so much impurities that the solution turns dark green? Any idea what it might be?

[akcapr]

you shoodent have heated the beaker cuz that helped the no2 escape the solution.

[jdurg]

Silver is commonly mixed with copper and nickel which will give green nitrate solutions.

[encipher]

Ah, but the silver I bought was apparently 99.9% pure. Got it off united nuclear. Could it that .01% make that big of a difference. Or might it me much more impure?

[encipher]

Ok, I took a look at it now. I can see the white AgNO3 crystals and whats left of the liquid is a blue solution, probably copper. I'm going to leave it for a while, then take it out and filter it. Looks good

 

 

Oh yeah, and would anyone happen to know how to neutralize or get rid of NO2 in the bathroom...

 

thanks

[YT2095]

you could pour a small amount of ammonium hydroxide on a plate and leave it in there for a while.

[H2SO4]

refrsh my memory is ammonim hydroxide common ammonia solution?

[YT2095]

it is yes.

 

Ammonia on it`s own is a gas like HCl is.

[woelen]

The green color is due to dissolved NO2. I also did a similar experiment, by dissolving 99.999% Bi metal in reagent grade 68% HNO3. Bi(3+) ions are colorless, but the solution becomes a nice green.

 

What really happens is that quite some NO2 dissolves in the liquid. NO2 is brown. It partly disproporionates to form NO and HNO3 with the water in the liquid. NO in turn reacts with more NO2 to form the deep blue N2O3.

 

The mix of deep blue N2O3 and brown NO2 can have all colors ranging from nice green to brown/yellow, depending on the ratio of NO2/N2O3.

 

If you dilute your solution with water, then you'll see that its color quickly disappears and that it becomes colorless. All N2O3 then reacts with the water, forming HNO3 and NO, and NO2 also reacts with water, forming HNO3 and NO. The NO bubbles out of solution as a colorless gas.

 

If the green color persists on dilution, then your silver was impure, and indeed may contain nickel, chromium or copper. But I do not expect that to happen, just try it with a small amount from your solution.

 

====================================

 

Now a word of warning: NEVER do dissolve so much metal in HNO3 again, when you have no good way to get out of the NO2. Seriously, NO2 can kill you. It is particularly insidious, because it has a delayed effect. At first, it does not feel that bad, but 24 hours later, you can have serious edemia and it has happened before that people "drowned" in their own water, formed in the lungs, many hours after a serious NO2-exposure. Chemistry is fun, but don't play with your life!

 

If after 24 hours you still do not have any complaints, then there is no need to worry anymore. But next time, please be more careful. E.g. you could add acid in small portions. It takes some more patience. Another option might be to go out to a place in the free field and do the experiment over there, or wait until you have a really windy day and all gas is blown away immediately.

[encipher]

Yeah, I shouldnt have done that. Funny thing is that it had a delayed reaction. At first nothing was happening, I figured I hadn't added enough acid so I added some more. I then went to get a drink and then came back. I saw the thing smoking like crazy.

 

I found out that the bluish green stuff was dissolved NO2. I was pouring it down the sink and NO2 gas started coming out. Well, thanks and hopefully I'll still be alive 24 hours from now.