Volanschemia
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Magnesium and Silver(I) Nitrate
I just did the Magnesium and Silver Nitrate deflagration the other day. Such a great reaction, and it's produced the brightest flash out of all my
combustion reactions (besides thermite perhaps).
It's also leaves a fantastic black mark behind. Am I right in thinking that's tiny silver particles?
I set up my own dripping apparatus out of a bottle, some vinyl tubing and an inline tap as I don't have a burette (and if I did it wouldn't be sitting
over an explosion site). I will post some pictures soon.
Sources: File Attached (Found on the Internet)
Stoichiometry: I used 0.5g of 500 mesh Magnesium Powder and 1.2g of Silver Nitrate that was ground in a mortar and pestle and then thoroughly dried in
an oven.
The reaction: 2AgNO3 + Mg = Mg(NO3)2 + 2Ag
PS. As a side note, how many people on here have worked with silver compounds and gotten silver stains on your hands? They seem to be very hard to
avoid. I was wearing gloves and I still somehow got some small black dots on my hands!
PPS. Just noticed that spell check doesn't recognize 'Deflagration', 'Thermite', or 'Burette'.
Attachment: Displacement of magnesium with silver nitrate.doc (71kB)
This file has been downloaded 5259 times
[Edited on 30-1-2015 by TheAustralianScientist]
"The chemists are a strange class of mortals, impelled by an almost insane impulse to seek their pleasures amid smoke and
vapor, soot and flame, poisons and poverty; yet among all these evils I seem to live so sweetly that may I die if I were to change places with the
Persian king" - Johann Joachim Becher, 1635 to 1682.
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Dornier 335A
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I have tried it. I used freshly milled 20 µm magnesium powder and mixed it very well with silver nitrate just before use. I must say that I was
scared of premature ignition because I didn't actively dry the silver nitrate beforehand. Nothing bad happened though and the mixture exploded with a
deep POOF when touched with a wet stick. I did not experience it as particularly bright, but that might be due to it's incredible burn speed. It was
faster than most other flash powders I've made. The tests can be found here: https://www.youtube.com/watch?v=RcflI_gQMYA
I too got those small black dots on my hands...
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simply RED
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Excuse me, Dornier, it is not on the topic, but you present a graphic in one of your videos (lost link) that you made flash powder with energy content
12 MJ/kg. May you post the composition and how you calculated this?
When logic and proportion have fallen sloppy dead...
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Dornier 335A
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I suppose you're referring to my report compositions video? That would be Mg/NaNO3 flash powder. I used 55% Mg and 45% NaNO3,
the ratio I've found to burn the fastest. I can't remember how I calculated it in the video so I'll do it again.
2 NaNO3 + 8 Mg → Na2O + 5 MgO + N2 + 3 Mg(g)
3 Mg(g) + 1.5 O2 → 3 MgO
The total molar weight of the reactants is 279.44 g.
The ∆H of the first one is: 5*(-601.8)+(-416)-(2*(-467)) = -2491 kJ
And for the full reaction including the secondary combustion:
8*(-601.8)+(-416)-(2*(-467)) = -4296.4 kJ
2.491 MJ/mol / 0.27944 kg/mol = 8.9 MJ/kg
4.2964 MJ/mol / 0.27944 kg/mol = 15.4 MJ/kg
In a detonation only the first reaction would have mattered but in this case (testing report compositions) the secondary, thermobaric reaction adds to
the sound and is relevant.
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simply RED
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Indeed, it can't be without using oxygen from the air. Thanx.
When logic and proportion have fallen sloppy dead...
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Bert
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Thread Moved
30-1-2015 at 09:24 |
Bert
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OP: Edit to show your sources of information, give stoichiometry, generally try to describe experiment more precisely.
Then this can go back into EM.
(Edit)
THANKS! back to EM-
Yes, it can go off before you're expecting. Keep quantities SMALL.
[Edited on 31-1-2015 by Bert]
Rapopart’s Rules for critical commentary:
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Anatol Rapoport was a Russian-born American mathematical psychologist (1911-2007).
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Fulmen
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Silver nitrate is also a simple qualitative test for pure/alloyed Mg. It will instantly produce a black spot on pure Mg but not on any of the common
alloys.
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Bert
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Yes-
A quick, cheap test for high % Mg presence in alloy: Just file or sand a small area clean, then brush on common white vinegar (5% acetic acid). High
Mg alloys will quickly bubble, Al won't.
Rapopart’s Rules for critical commentary:
1. Attempt to re-express your target’s position so clearly, vividly and fairly that your target says: “Thanks, I wish I’d thought of putting it
that way.”
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3. Mention anything you have learned from your target.
4. Only then are you permitted to say so much as a word of rebuttal or criticism.
Anatol Rapoport was a Russian-born American mathematical psychologist (1911-2007).
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blogfast25
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The reduction of Na2O with Mg is also thermodynamically favourable:
Na2O + Mg === > 2 Na + MgO
∆H<sub>reaction</sub> = - 602 -(- 418) = - 184 kJ/mol (NIST values for ∆H<sub>formation</sub> of the reagents)
This reaction has also been carried out in practice and reported here, but using NaOH instead of Na2O.
[Edited on 30-1-2015 by blogfast25]
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Bert
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Thread Moved
30-1-2015 at 16:07 |
Bert
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Fine unoxidized Mg powder is so much fun, it just lends itself to the more spectacular chemistry demos... There was a time it was included in kid's
hobby chemistry sets. No more, at least in USA.
Try not to lose any fingers, and wear safety glasses that stop UV light. I made the mistake of looking at such reactions from way too close without
proper eye protection as a teen.
A mixture of Mg and finely powdered PTFE (Teflon) is energetic, and a bit safer on a humid day- POOF!
Rapopart’s Rules for critical commentary:
1. Attempt to re-express your target’s position so clearly, vividly and fairly that your target says: “Thanks, I wish I’d thought of putting it
that way.”
2. List any points of agreement (especially if they are not matters of general or widespread agreement).
3. Mention anything you have learned from your target.
4. Only then are you permitted to say so much as a word of rebuttal or criticism.
Anatol Rapoport was a Russian-born American mathematical psychologist (1911-2007).
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Volanschemia
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Quote: Originally posted by Bert  | Fine unoxidized Mg powder is so much fun, it just lends itself to the more spectacular chemistry demos... There was a time it was included in kid's
hobby chemistry sets. No more, at least in USA.
Try not to lose any fingers, and wear safety glasses that stop UV light. I made the mistake of looking at such reactions from way too close without
proper eye protection as a teen.
A mixture of Mg and finely powdered PTFE (Teflon) is energetic, and a bit safer on a humid day- POOF!
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Thankyou.
New to the forum so still some learning to be done. 
I might have a look at PTFE/Mg flash powder. Looks pretty fun!
Yes, it's a shame about the demise of the chemistry set. Most of them now proudly proclaim "NO CHEMICALS". 
[Edited on 31-1-2015 by TheAustralianScientist]
"The chemists are a strange class of mortals, impelled by an almost insane impulse to seek their pleasures amid smoke and
vapor, soot and flame, poisons and poverty; yet among all these evils I seem to live so sweetly that may I die if I were to change places with the
Persian king" - Johann Joachim Becher, 1635 to 1682.
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PHILOU Zrealone
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During the explosion, due to the heat of reaction, Mg(NO3)2 isn't present anymore
So
2AgNO3 + Mg ==> Mg(NO3)2 + 2Ag
becomes
2AgNO3 + Mg ==> MgO +N2 + NxOy + N2 + 2 Ag
(and maybe some Mg3N2)
[Edited on 31-1-2015 by PHILOU Zrealone]
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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Molecular Manipulations
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Why not:
2 Ag(NO3) + 6 Mg → 2 Ag + 6 MgO + N2
Magnesium can easily reduce any nitrogen oxide, so only if silver nitrate is in great excess will any nitrogen oxides form.
[Edited on 31-1-2015 by Molecular Manipulations]
-The manipulator
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Volanschemia
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Photos
As promised, here are some photos of my dripping setup.
I have a desk three levels. There is a soft drink bottle with some water in it and a pipe glued in the bottom with Araldite. The pipe goes through a
hole in the top level and is attached to an inline tap glued into position so it lets a drop of water through every 15 seconds. Some more pipe is
attached to the other end of the inline tap and dangles over the spot where the mix will be placed. While setting up, the bottle is on the middle
level so water cannot get to the tap. When I am ready for the reaction, I move the bottle up onto the top level on top of a bucket and a dog food tin
and the water runs through the pipe to the tap. 15 seconds later: POOF! 
     
"The chemists are a strange class of mortals, impelled by an almost insane impulse to seek their pleasures amid smoke and
vapor, soot and flame, poisons and poverty; yet among all these evils I seem to live so sweetly that may I die if I were to change places with the
Persian king" - Johann Joachim Becher, 1635 to 1682.
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Trotsky
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Is this blend shock sensitive? I've seen lots of videos over the years of water being used to initiate the reaction, but I've always wondered if
hitting it with a hammer would do. I assume so, but I've not seen it done.
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Fulmen
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Any composition containing magnesium metal should be considered highly sensitive to shock ,friction, heat, insults and foul language.
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Wizzard
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Maybe anecdotal, but I avoid silver stains by keeping out of the sun / UV light sources, and soaking with a very mild base (milk works OK, heavy soap
also works). Usually comes off enough that the stain (still present) is hardly visible.
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