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Author: Subject: Silver / Copper Nitride
hodges
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[*] posted on 15-4-2004 at 14:47
Silver / Copper Nitride


I have read that silver nitride (Ag3N) is about as easy to make as nitrogen tri-iodide and just as sensitive. Has anyone made it? I'm curious as to why we don't hear more about it. It seems most people would have an easier time getting silver compounds than iodine.

What about copper nitride - is it easily made and is it explosive?
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[*] posted on 15-4-2004 at 17:36


I know that the silver was briefly discussed as an off-topic discussion somewhere here. It is made by the heating of silver oxide in concentrated ammonia.

Here is some info on the preparation of nitrides by Blaster:

Quote:

They are easily made from the metal oxide and conc. ammonia soln - heat gently until most of the water has evaporated then allow to air dry.
When making the metal nitrides, you should be safe, even with a bunsen, as long as you don't let it boil dry - the water and ammonia evaporation keeps it below 100'C and therefore below the detonation temperature.
You do need to heat for some time - just boiling briefly isn't enough. My first attempts with the Silver compound failed cos I just boiled it dry with a bunsen within a few seconds. Just as well really!!!
For best results, heat the metal oxide and ammonia on a temperature controlled hot plate at a low heat and add extra ammonia soln two or three times but don't let it dry out between additions!
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[*] posted on 17-4-2004 at 12:03
Ag3N - No Success


I precipitated some Ag2O from a AgNO3 solution using excess NaOH. I put a small amount (miligrams) of this on a flat surface and added 2.5M NH4OH. Although the precipitate did seem to darken from brown to a rather black color, it was not explosive when dry. I scraped and hit it with a broom handle and even tried to ignite it with a barbecue lighter and it did nothing. I got the same results both when leaving the excess NaOH in the precipitate, and when washing it first before adding the NH4OH.
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[*] posted on 17-4-2004 at 12:09


Did you do any heating or did you just add the amomoia and filter again? How long did you keep it in the ammonia solution?
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[*] posted on 17-4-2004 at 17:45


I think that I remember reading somewhere that it explodes readily even in solution. I would say that would make it a bit more sensitive then nitrogen triiodide.



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[*] posted on 17-4-2004 at 17:59


Quote:
Originally posted by rogue chemist
Did you do any heating or did you just add the amomoia and filter again? How long did you keep it in the ammonia solution?


I left a small amount of the solution with the precipitate in a test tube. With an eye dropper, I picked up some of the precipitate/solution and placed it on a flat surface. I added NH4OH to this with another eye dropper.

The precipitate that I washed first dried completely. The precipitate with excess NaOH never did dry completely due to the hygroscopic nature of NaOH.

I know 2.5M is not very strong for NH4OH. I have made NI3 quite successfully with this strength before though.

Does anyone have an equation for the reaction that is supposed to occur (fulminating silver)? I searched the net for articles containing Ag2O and AgN3 and didn't find any matches. I have read that the danger during silvering is when the pH of the solution is very high. I think that would imply a reduction, but Ag is +1 in both Ag2O and AgN3 I believe.

[Edited on 4/18/04 by hodges]
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[*] posted on 17-4-2004 at 18:50


If I was to be making this(I will when I can get ahold of concentrated ammonia) I would be using a bit larger scale in the procedure. It is possible that the way you did it that there simply was not enough ammonia present.
This what I am planning on doing.
1. .1-.5g Ag2O in a 100mL beaker with ammonia
2. boil till about 20-30 mL of solution is left
3. add more ammonia to the beaker.
4. Repeat steps 2-3 till I'm sick of it :D
5. filter

[Edited on 18-4-2004 by rogue chemist]
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[*] posted on 19-4-2004 at 13:22


<blockquote>quote:<hr><i>Originally posted by hodges</i><br>Does anyone have an equation for the reaction that is supposed to occur (fulminating silver)? I searched the net for articles containing Ag2O and AgN3 and didn't find any matches...<hr></blockquote>AgN<sub>3</sub> is silver azide, silver nitride is Ag<sub>3</sub>N, equation:
3Ag<sub>2</sub>O + 2NH<sub>3</sub> <s>&nbsp;&nbsp;&nbsp;></s> 2Ag<sub>3</sub>N + 3H<sub>2</sub>O




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[*] posted on 19-4-2004 at 13:29


Taken from the Comprehensive Inorganic Chemistry series:
Quote:

Silver Nitride

Ag3N

Potassium hydroxide pellets are added to a solution of AgCl in conc. ammonia until the effervescence, caused by the evolving NH3, stops. The mixture is diluted with distilled water, filtered through filter paper, and washed with water until the filtrate is neutral. The moist product is transferred from the filter paper to a porcelain dish, where it may be stored under water for some time.
The product contains small amounts of AgCl and Ag, bus is free of Ag2O.

Alternate Methods: a) A solution of Ag2O in conc. aqueous ammonia is allowed to stand in air or heated on a water bath. The same may be achieved by precipitation with alcohol. The product is impure, with a variable content of Ag2O and Ag [F. Raschig, Liebigs Ann. 233, 93 (1886)].
b) Solid AgF*2NH3 is stored for several days over H2SO4 in a desiccator. The product is free of Ag2O and rich in Ag; the yield is small [L. J. Olmer and Dervin, Bull. Soc. Chim. France (4) 35, 152 (1924)]

SYNONYM:
(Berthollet's) fulminating or detonating silver.

Properties:
Formula weight 337.65. Black flakes, sometimes shining black; crystalline appearance (when prepared according to Raschig, see above). Insoluble in H2O, soluble in dilute mineral acids, explosive reaction with conc. acids. Both the dry and the moist product may be stored in air at room temperature for a long time. Slowly decomposes at 25C. Decomposes at room temperature in vacuum. Decomposes explosively in air at about 165C. Very sensitive (explodes) when touched with objects of great relative hardness, even when moist. Extremely sensitive when dry, but relatively easy to handle when moist. Explodes readily when prepared by Raschig's method. d1/4 9.0. Crystal structure: cubic. Heat of formation (25C): +61.0 kcal./mol.

REFERENCE:
H. Hahn and E. Gilbert. Z. anorg. Chem. 258, 77 (1949).




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[*] posted on 19-4-2004 at 16:48


Thanks, Kaboom and BromicAcid, for the detailed information. Yeah, I meant to type Ag3N not AgN3, it was a typo.

I tried a couple more experiments. I made a more concentrated NH4OH solution using NH4Cl and NaOH. In the first experiment, I had two solutions - one AgNO3 in water and the other NaOH + NH4Cl in water. I made the second solution by adding an excess of NaOH to the water and then adding NH4Cl. Considerable NH3 gas was evolved, and bubbling continued for quite a while. I mixed this with the AgNO3 solution. I got a black precipitate as expected. I left it sit, but it would not dry because of the excess NaOH. So I washed it with a bit of water and let it dry in several small piles (probably around 0.01g each) on a flat surface. Once dry, when touched with the butane flame of a barbecue lighter, there were a few small "rice crispy" pops.

In the second experiment, I mixed NaOH solution with AgNO3 solution and got a black precipitate. I then added NH4Cl. There was only a small amount of bubbling, and it seemed that some of the Ag2O dissolved when I added the NH4Cl. I added more NaOH and got some more bubbling, but I could tell that there was brown Ag2O present in addition to anything else. I let some of this dry and got no reaction whatsoever to a flame.

I'm thinking that Ag3N only forms if it precipitates as it forms. If solid Ag2O is present, maybe it does not react (possibly due to low soluability).

I wonder why the preferred synthesis method calls for AgCl instead of AgNO3. I wonder if there is a reason, or whether AgCl was just thought to be more common.
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[*] posted on 22-4-2004 at 15:02
Success!


I was successful, even without a source of concentrated NH4OH. I took 0.25 grams of AgNO3 and 1g of NH4NO3. I added a small amount of water - just slightly more than required to dissolve the two salts. I used a paper cup. I then slowly, a few grains at a time, added NaOH over a period of an hour or so. Once adding NaOH was no longer giving much NH3 gas, I let it sit for another half hour. I then filled the cup the rest of the way with water. I saw plenty of dark black flakes, some of them appearing to have a bit of silver on them as well. I let this settle for a few minutes, then poured off most of the water. I repeated the washing several times. After the last washing, I left a small amount of water in the cup with the precipitate. Using a plastic dropper, I pulled precipitate/water from the bottom of the cup and deposited it in about a dozen equal amounts on a flat surface.

After drying, each spot gives a loud SNAP! when ignited with a barbecue lighter, blowing out the lighter and leaving only a black mark behind. I also tried setting one off with a piece of string that had been previously soaked in KNO3 solution. With a loud SNAP! (though not much flame that I could see), the wick was thrown several feet into the air. I also tried setting these off by hitting with a broom handle. Most of them could not be set off this way, although two were.

Given the amount of materials I started with and the fact that I lost some during washing, I would estimate each pile had 0.01g of Ag3N in it. The explosions were not as loud as a fircracker, but much louder than toy caps or snappers.
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[*] posted on 1-5-2004 at 13:45


I did some more experiments with this substance. What I have found is that it (at least when made with my above method, which may not be too pure) the substance is similar in sensitivity and power to the substance in toy caps (which is Armstrong's mixture I believe).

I made about 0.15 grams of Ag3N, and kept it under water after washing the precipitate. With a plastic dropper, I pick up small (several miligram) amounts and place the wet drops on a flat surface to dry. Once dry, I can scratch the surface with a wooden stick without it detonating. Hitting it with a piece of metal, however, causes it to detonate just somewhat more loudly than a toy cap gun (do they still make these things?). There is no visible flame - it appears that the substance just dissapears when struck. I even tried measuing the temperature of the surface after detonation with an infrared thermometer. Results varied from no change to a 1 degree C rise in termperature.

If instead of placing the drops of precipitate on a flat surface I place them on a piece of paper towel and then ignite the paper towel when dry, each drop goes off with a bang (again, about as loud as a cap gun) as the flame reaches it.

I took a few pictures and will post later when I've got Windows booted up again (running linux at the moment).
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[*] posted on 2-5-2004 at 15:04


Here is about 150 mg of Ag3N (the black precipitate), sitting under water in a paper cup after preparation and washing:


Here are small spots of Ag3N, placed from the water solution with a plastic dropper. Each spot is several miligrams. The one on the right is nearly dry.


Here is the same shot after detonating the right spot of Ag3N. Very little residue.
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sad.gif posted on 15-5-2004 at 13:27
Copper nitride synth. failed


I've tried the procedure described in the document extracted from a book, that says to add KOH to an ammoniacal solution of AgCl.
Well, I've added some CuCl in NH4OH and then, added some NaOH.
The dark blue precipitate, when dry, doesn't explode.

Please tell me the correct procedure for making copper nitride.

Thanx at all for the collaboration.
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[*] posted on 16-5-2004 at 12:53
Copper Nitride


I just checked and CRC lists copper nitride as Cu3N, a dark green powder that decomposes in water and in air at 300C. Nothing about it being explosive. Anyway, since it decomposes in water it could not be made in water solution.
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[*] posted on 25-8-2004 at 10:38


I've done silver nitride and the only thing I can say is "TAKE CARE" !

I did 0,05g of it by adding silver nitrate to a drop of NaOH 30% and then adding NH3(aq) 12%. After a few days it became dark and I filtered it. I let it dried and when I touched the crystals with a plastic spoon to collect them : BANG !

So be careful if you try to make it, it's fucking dangerous...

you can also make these (I don't know if they work, I haven't tested it yet but I'm planning to) :

Fulminating Gold : First add as much NH4Cl as you can to HNO3 70% and then add the gold. Wait 10 days and add potassium carbonate, fulminating gold should precipitate

Fulminating Mercury : Add 0,6g of red mercury oxide to 10ml conc NH3(aq) in a sealed tube for 10days, it should turn gray or white.

Fulminating Copper : Add metalic copper to fulminating silver or gold and add a few drops of water.

I've also seen listed as explosives fulminating platinum and other metals but I don't have much more informations...
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[*] posted on 25-8-2004 at 13:22


Are you talking about nitrides or azides? The latter would be much more explosive.

BTW "Fulminates" are supposed to be isocyanates, derivatives of the unknown acid HONC, so you cannot have been making these. (Cyanic acid is HOCN)

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[*] posted on 26-8-2004 at 09:28


just to say that I've tested the fulminating mercury and it works :)
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[*] posted on 30-8-2004 at 14:28


Quote:
Originally posted by JohnWW
BTW "Fulminates" are supposed to be isocyanates

fulminates differ from isocyanates see CNO- ion
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[*] posted on 4-9-2004 at 09:38


Kinda off topic, but since we're on the topic on nitrides.... How come lithium nitride doesn't explode?



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[*] posted on 4-9-2004 at 10:34
Alternate way to mercury nitride...


Found this, production of what looks like an allotrope of nitrogen prepared electrically in a similar way to ozone that produces mercury nitride directly in one step from the Hg metal itself.

http://lateralscience.co.uk/activen/index.html

The rest of the site is pretty amusing too, especially the fictional Glitch chronicles:D




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[*] posted on 4-9-2004 at 16:36


Saerynide:Li<sub>3</sub>N is more stable than Ag<sub>3</sub>N because Li is much more reactive than Ag, liberating that pesky octet-preventing electron very easily while Ag prefers to hold onto it. Another reason is no doubt that the covalent radius of silver is so large, while that of nitrogen is so small. This is why NI<sub>3</sub> is so unstable.

Quote:
from Encarta
Nitrogen... is converted to an active form by passing through an electric discharge at low pressure. The nitrogen so produced is very active, combining with alkali metals to form azides; with the vapor of zinc, mercury cadmium, and arsenic to form nitrides; and with many hydrocarbons to form hydrocyanic acid and cyanides, also known as nitriles. Activated nitrogen returns to ordinary nitrogen in about one minute.


Oooh...azides from alkali metals in one easy step... :D
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[*] posted on 17-3-2006 at 15:06
A Slight Mishap


Just got around to posting these. About a month ago I made some silver nitride. When I started to add water to the AgNO3/NH4NO3/KOH following the synthesis, the mixture exploded, splattering all over the ceiling and walls (as well as my shirt and arm).

I suspect that some of the Ag3N had dried on the surface, since I used a minimal amount of water and had let the reaction sit for an hour or so to ensure it was complete. When the first drop of water hit, it exploded. The exploson was not very loud - sounded more like a cork popping out of a bottle than a loud bang. I noted that most of the mixture remained in the plastic cup, which was unharmed.

I quickly washed the mixture off of me since KOH is not particularly good for the skin. After cleaning myself up I wiped the mess off the ceiling and walls. However, it left stains due to the silver. I was later able to remove these completely with dilute HNO3 (which surprisingly did not harm the paint). I washed the Ag3N that remained in the cup and found it to still be explosive upon drying.

Here are some pictures (around 650kB each), taken with a Kodak EasyShare camera:

http://www.sciencemadness.org/scipics/Ag3N_0118.JPG
http://www.sciencemadness.org/scipics/Ag3N_0119.JPG

The black substance in the cup under the water faucet is the Ag3N which exploded. Another cup is visible in one of the pictures; this was from an unrelated experment.

What I was testing is what happens to Ag3N over time. I kept a sample of it under water, and I noted that small bubbles were visible in it for a couple of weeks. After this the bubbles stopped, and I found that the compound is no longer explosive. It also now has a gritty character which the Ag3N did not. I suspect it is now a harmless mixture of Ag and Ag2O.
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[*] posted on 18-3-2006 at 13:11


Hodges, you are talking about Ag3N, but isn't this fulminating silver? (not to be confused with silver fulminate).

If you prepare Tollen's reagent (ammoniacal silver solution), then you always read warnings about the possible formation of so-called fulminating silver. A crystalline crust can form, when an ammoniacal silver solution is allowed to stand for some time. When this crust is cracked, then it explodes. This is why ammoniacal silver solutions should be prepared, just before they are needed, and any solution, left over should be destroyed by acidifying it.




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[*] posted on 18-3-2006 at 13:29


Fulminating silver is just another name for silver nitride, Ag3N.



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