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PHILOU Zrealone
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[*] posted on 5-9-2009 at 10:08


Quote: Originally posted by hodges  
Quote: Originally posted by PHILOU Zrealone  

-You can make 3 variety of silver acetylide:
1°) the neutral process, via bubbling C2H2 into silver acetate solution
2°) the basic process, via bubbling C2H2 into AgOH solution into ammonia water
3°) the acidic process, via bubbling C2H2 into AgN03 solution

The sequence of stability is 3>1>>2 and the sequence of power and VOD is 3>>1=2!



I have a small amount of silver acetylide, made using method #2, that has been stored under water for over 3 years. It started out white and has now darkened to dark gray. Just tested some recently and seems to act the same as before.

Hodges

:( I'm sorry it is my fault: by stability, I meant sensitivity (-> to shock/friction/heat). Stability of course refers as you stated to storage stability.

The number 2 contains some Ag3N, Ag2NH and AgNH2 nightmare of mirror makers...reason of its higher sensitivity than its neutral or acidic homologs.




PH Z (PHILOU Zrealone)

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nitro-genes
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[*] posted on 6-9-2009 at 07:21



I've gone through most of the possible influential factors by process of elimination, including temperature of the AgNO3 solution, HNO3 concentration (Although not necessary below 10% AgNO3 solutions), speed by which acteylene was bubbled through, washing with different solvents to decrease drying time, influence of performing the reaction in the complete dark, etc etc.

At the end, I came to the conclusion that the most important factor that determines the quality of the complex must be the purity of the acetylene. Use of calcium carbide generators has been associated with dark coloured complexes, which is no suprise since calcium carbide involves a reasonably aspecific reaction at higher temperatures, producing numerous by products:

http://www.absoluteastronomy.com/topics/Acetylene -->

Impurities in acetylene are easily detectable by smell. Pure acetylene is a colorless and odorless gas. The characteristic garlic-like odor of technical grade acetylene is attributable to contamination by impurities. Impurities which may be present include: divinyl sulfide, ammonia, oxygen, nitrogen, phosphine, arsine, methane, carbon dioxide, carbon monoxide, hydrogen sulfide, vinylacetylene, divinyl acetylene, diacetylene, propadiene, hexadiene, butadienyl acetylene, and methyl acetylene.

The last 7 would be hard to exclude from the acetylene generated and could have impairing effects on the formation of the complex, perhaps by forming an unstable complex with Ag2C2 or AgNO3 themselves. Since with some batches of calcium carbide the complex turns brown/grey from the first bubble of acetylene, some impurities might reduce AgNO3 directly thus introducing metallic silver. Use of pressurized acetylene, which needs to be chemically pure due to safety regulations, could provide an answer...

[Edited on 6-9-2009 by nitro-genes]
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watson.fawkes
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[*] posted on 6-9-2009 at 08:04


Quote: Originally posted by nitro-genes  
At the end, I came to the conclusion that the most important factor that determines the quality of the complex must be the purity of the acetylene.
Here's what Purification of Laboratory Chemicals has to say on the subject:
Quote:
Acetylene [74-86-21] M 26.0, m -80.8°, b -84°, pK -25. If very impure it should be purified by
successive passage through spiral wash bottles containing, in this order, satd aq NaHSO4, H20, 0.2M iodine in
aq KI (two bottles), sodium thiosulfate soln (two bottles), alkaline sodium hydrosulfite with sodium
anthraquinone-2-sulfonate as indicator (two bottles), and 10% aqueous KOH soln (two bottles). The gas was
then passed through a Dry-ice trap and two drying tubes, the first containing CaCl2, and the second, Dehydrite
[Mg(C104)2] [Conn, Kistiakowsky and Smith J Am Chem Soc 61 1868 1939]. Acetone vapour can be
removed from acetylene by passage through H2O, then concd H2S04, or by passage through two gas traps at
-65° and -80°, concd H2SO4 and a soda lime tower, a tower of 1-mesh Al2O3 then into H2SO4 [Org Synth Coll
Vol 1 229 1941,3 853 1955; 4 793 1963]. Sometimes it contains acetone and air. These can be removed by
a series of bulb-to-bulb distns, e.g. a train consisting of a conc H2SO4 trap and a cold EtOH trap (-73° ), or
passage through H2O and H2SO4, then over KOH and CaCl2. [See Brandsma Preparative Acetylenic Chemistry,
1st Edn Elsevier 1971, for pK p15, ISBN 0444409475; 2nd Edn Elsevier 1988, ISBN 0444429603, and Chapter
5 for sodium acetylide.] It is also available commercially as 10ppm in helium, and several concentrations in N2
for instrument calibration.
Note: OCR errors may remain.
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hodges
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[*] posted on 6-9-2009 at 15:57


Quote: Originally posted by PHILOU Zrealone  
by stability, I meant sensitivity (-> to shock/friction/heat). Stability of course refers as you stated to storage stability.

The number 2 contains some Ag3N, Ag2NH and AgNH2 nightmare of mirror makers...reason of its higher sensitivity than its neutral or acidic homologs.


I played around with this some. I made some #3, and allowed a small amount to dry in several places on my cement patio. I also took some of the #2 I had left over from 3 years ago and allowed this to dry in several spots on the patio as well.

I found #2 to be more sensitive, but only slightly. Both #2 and #3 required a pretty good hit with a hammer to get them to detonate. For a friction test, I tried scratching the cement with a metal screwdriver. I had to press hard and scrape fast to get either to detonate. Perhaps the sensitivity for #2 decreases with age.

Hodges
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edmo
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[*] posted on 16-9-2009 at 03:59


All acids will eat through a lot more than you expect. I only trust LDPE and even not that far now.

I would not trust anything with a peroxide+.
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[*] posted on 22-9-2009 at 11:38


LDPE isn't all that great - HDPE, PTFE, Acrylic also I think should be very chemically resistant. However HNO3 will turn even HDPE bottles brittle over a sustained period of storage.

I still have the acid marks on my desk from one particular accident of this nature...
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prometheus1970
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[*] posted on 28-1-2011 at 12:41


If dissolving pure silver in HNO3 how many grams AG, how many ml HNO3? Then add a little distilled water before H2C2 addition or bubble gas through acid/AG soln.?

[Edited on 1-28-2011 by prometheus1970]




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Dr.Bob
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[*] posted on 2-2-2011 at 20:35


Reading up about accidents reminds me of a few "Doh" moments. Many are 20+ years old during my younger years as a chemist.

A friend tried to make TNT once in high school in a sink by mixing the toluene, H2SO4, and nitric acid in a polystyrene coffee cup while the teacher was out for a while. Not too good. The toluene ate through the cup within seconds. So he tried to wash it down the drain a little. The acid corroded the drain pipe, and then leaked on the supply pipe. A short while later, the pipe suddenly burst, shooting hot water all over, especially on my friend and his stuff who was sitting next to it. Fortunately, the teacher did not find out what he was up to. The maintenance guy was complaining about how corroded the pipes had gotten.

Another guy I knew in college made a reactive mixture, played with it some and then went off to college after a while. He left the excess material in a glass jar under his bed... His family called after the house caught fire, and the fire Chief was asking about the "accellerant" in the bedroom. I think he claimed that he had some fuel for a RC car or plane and eventually was not charged. But his bedroom was burned badly.

I tried to make acetylene as a kid and succeeded, only to find that when I burned it, it created thick black smoke that stuck to the white curtains in the bathroom. <y mother was VERY unhappy, and all new experiments went outside...

Fortunately, as next I was playing with sodium peroxide (it used to be easy to purchase really hazardous chemicals 30 years ago...) and my reactor, a paper cup, burst into flames spontaneously on a humid summer day. After that I found that you could pour a bit on a paper towel, roll it up, spit on one end and start a fire easily, even with wet wood. Even better with wet wood... I had some boy scout friends really amazed.

Tried to make some rocket motors with Zn and sulfur. Worked a few times, biggest one just blew up in an enormous cloud of smoke. Neighbor thought that their house was on fire.

Best one was making a "model" volcano for school project. It was 2' by 2', with a 16 oz tin can as the top opening. I had filled it with 1/4 layers of thermite, flask powder, smoke mix, Ammonium dichromate, etc to the top. The teacher must have assumed I was going to mix NaHCO3 and vinegar, but I suggested that it would be better to demonstrate outside. It shot flames 3 feet high and created a smoke cloud a block wide. Some teachers saw it and thought the school was on fire. But the kids in my class were amazed, and I think I got an "A". But the teacher suggested that I keep my chemicals at home. Now I would be a terrorist.

Another time, I asked the teacher what would happen if we mixed KMnO4 and glyerol. She didn't know, she we tried. Yet another large flaming beaker, fortunately small scale and on a soaprock bench. Thankfully, also not under a sprinkler head.

Perhaps you see a trend here. Some of my friends somehow got the impression that I was a pyromanic or something. Looking back, I wonder how I didn't catch my house on fire, burn myself or get arrested. But now I am a productive member of society (who happens to still like fire, but is more careful).

Bob
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prometheus1970
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[*] posted on 3-2-2011 at 07:12


I appreciate the anecdotes (I have several of my own). I've learned to be more respectful of primaries. Once again, though, It was not carelessness that caused my mishap, it was poor judgement. I apologize if you already understand this, but everyone seems to think I was just smoking around a pile of explosives like a dumbshit when it went off. However, that was not the case. I was testing a tiny piece of Ag2C2 for dryness/ viability by holding a lit cigarette to it without properly shielding the remainder of the batch from possible flashover. I do appreciate your reminding me of the potential dire consequences of this hobby. I just want to be sure everyone understands it was not a case of blatant carelessness, but one of a lack of foresight.



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[*] posted on 3-2-2011 at 08:24


Don't use a PET plastic bottles to hold 70% nitric acid!!!
i just used one to hold 1 liter of this stuff, and its eat the plastic and eat all my wood lab closet ! make all my wood yellow, and almost react with the sodium hydroxide inside my wood closet !
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prometheus1970
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[*] posted on 3-2-2011 at 10:21


I don't use plastic bottles to hold HNO3. I mentioned using an LDPE bottle in my Ag2C2.AgNO3 synthesis, but that was just the gas generator part.

p.s. what is "PET"?

[Edited on 2-3-2011 by prometheus1970]




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[*] posted on 3-2-2011 at 10:33


PET is plastic with the number 1 in the triangle. Use #2, 4 and 5 (HDPE, LDPE and PP) for HNO3. I've used these without a problem.
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[*] posted on 3-2-2011 at 10:41


Polyethylene terephthalate, being an ester it is not surprising that it reacts with nitric acid.

http://en.wikipedia.org/wiki/Polyethylene_terephthalate
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peach
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[*] posted on 4-2-2011 at 19:12


PET is not a good choice for storing strong acids. I would be cautious storing anything but relatively inert stuff in it.

HDPE is about the best resistance gets in terms of plastics before you switch to fluoropolymers. It is usually more resistant than PP as well. Every bottle or container of chemical I've ever got in plastic has been in HDPE. HDPE is transparent, but things are added to it to make it white and more solid looking. With regards to resistance and extractables (which contaminate the contents), the transparent stuff is likely better.

Ultra high molecular weight polyethylene is used in bullet proof shields. Another useful property of UHMW-PE is that it's co-efficient of friction is not far off PTFE's, but PE is thermoformable whereas PTFE is not. PE is also used for permanent plastic traffic bollards. And, everyone's favourite, shopping bags.

I have painted the surface I do chemistry experiments on with polyurethane floor paint. It's not perfect, but it is more resistant than most other finishes and can be scrubbed clean again. I spilt concentrated sulphuric all over it just recently, when the rubber seal on a valve I was testing fell apart. I've had extremely concentrated base solutions on there as well, and solvents. The surface is certainly marked, the worst being from iodine, but it's not peeling off or blistering.

A dish would be a good idea, but I'm not too bothered about the surface getting mucky. If you're doing chemistry inside, over carpets, some method of containing things is far more important, when a carpet alone can cost hundreds of pounds.

In terms of faulty electrical equipment, my hotplate's controls stopped functioning properly quite early on it's life. I had suspected something fishy was afoot for a long, long time, as the stir bar control would seem to not cause any change in some regions. One day I remembered that my pH meter, which also has a temperature probe, came with a CD and that I could use it for data logging. I installed it on a really old, unused laptop and decided to put that on the surface with my chemistry experiments, so I can read the forum and references as I watch something going beside me.

I was heating a flask of water on the plate and stuck the thermometer in, then decided to see how linear the temperature control on the front was. Plotting the graph and seeing it appear in front of me, I was quite surprised to find not only regions where the temperature wasn't rising as I increased the setting, but FALLING.

The only thing I can attribute this to is reactive gas getting behind the controls, into the pots and onto the tracks inside.

It's not a major issue though. I can try giving them a clean or simply replace them. Pots are not expensive and just need a few minutes with a soldering iron.




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[*] posted on 4-2-2011 at 19:41


I had a small accident the other day that could have been worse then it really was...

I was testing my new homemade mini kiln when I wanted to see how it performed in a reduction firing. Last minute on cool down in this type you supply some sort of fuel being carbonous material like newspaper or something like Methanol. I chose methanol for its smoothness. So there I am dripping drop by drop as each flares up as it enters the kiln, nothing exciting hence the issue. For about 30 minutes I did this and after a while I just started to drip it from overhead streight from the bottle which went well for a while until I got overzelous with a big splash and it ignited the bottle of Heet in hand.

LMAO, it shot the remaining Methanol out of the bottle with such force it didn't have time to ignite it, thank god, and recoiled the bottle out of my hand backwards. Nice little woosh sound and I lost more then likely 5 years off my life but in the end no harm no foul(ok a little foul but alls well).





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[*] posted on 4-2-2011 at 20:50


When do we get to see photos of the kiln?

I'm getting all excited by the constant teasing.




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[*] posted on 4-2-2011 at 22:50


Soon enough, Not much to look at honestly, just what looks like a little mud beehive from the outside but effective non the lest, Im just praying that the element holds up long enough since I really didn't implement a means of changing it:D. I started small but after a couple little test runs ended up adding about 2" more of insulation and as of right now the lid has not been fully reinsulated but progress is there no doubt. I ran a test tonight to gage the temperature that it rose and it took about 45minutes to reach 1000 degrees F and about 2.5 hours to reach a little over 1500 degrees F.




Knowledge is useless to useless people...

"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story before."~Maynard James Keenan
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[*] posted on 5-2-2011 at 12:16


If you go for a Mk2, it might be worth looking into breeze blocks; metal researcher has tried them quite a few times and found they're a good source of cheap insulation.

There is also aerated concrete block, which has a low enough density it can be cut with a wood saw.

I have all those high temperature refractory bricks, not they're not very good insulators. I might have a go with the aerated blocks as an outer liner myself.




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[*] posted on 31-7-2011 at 09:24


That's one hell of an accident! Making mistakes happens to the best of us, unfortunately.

The interesting thing is that right before something bad happens, you got this gut feeling, "something's not right", "maybe I should put the acid in a glass beaker just in case", "I should keep an eye on this, just in case". I have never met an experimenter who has not had a gut feeling right before something actually went wrong in the lab.
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[*] posted on 31-7-2011 at 13:13


Quote: Originally posted by Polverone  
Until yesterday I didn't think that any common acid (including sulfuric) would attack plastics either. I don't know what sort of plastic it was; the bottom of the bottle holds the recycling code that tells what type it is, and it was destroyed. The bottle was originally used to hold sterile eye drops for use with contact lenses. I thought it would make a nice dropper bottle for small amounts of H2SO4 indoors (since I store the big jug outside in a cabinet). I came into my room and thought things smelled a little funny, but I was doing a reaction on the hotplate so I didn't think too much of it. Then I saw over on my shelf that there was a puddle of acid formed, and a thin stream falling on the table below the shelf. The acid was coming from the bottom of the bottle that I had set there.

When I tried to pick up the bottle to put it in a glass pan to take outside, the whole bottom fell away (that's when the acid went down the wall and onto the carpet). If I'd been thinking a little better I would have set the glass pan up to catch the acid instead of trying to move the bottle. But, of course, many things could have gone better (or worse) yesterday.

I am not too worried about vapors from this incident damaging computer equipment. I do think that my monitor is suffering progressive failure from exposure to various fumes, though. I was aware of the potential problems but this monitor has lasted several years and has a big scratch on the screen (from careless handling by someone moving it) anyhow.

There were probably 300-400 mL of acid in the bottle at the time of the incident.


You can get a rough idea of the type of plastic by feeling how hard it is. Hard plastics are usually thermosets (e.g. epoxy, bakelite) while softer ones are usually thermoplastics (e.g. polyethylene, polypropylene).

Thermosets are more susceptible to chemical attack because of their many functional groups; more functional groups implies more incompatibilities.

Thermoplastics with linear carbon chains and attached H or F atoms (e.g. PP, PE, PTFE) are obviously the least complex and least susceptible to chemical attack of different plastics.

[Edited on 31-7-2011 by Fusionfire]
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[*] posted on 24-9-2011 at 13:53


Be VERY, VERY careful indeed when working with hydrogen selenide!!! I found out why - THE HARD WAY!!! By accident I exposed myself to a HIGH concentration of the gas. The first sign of danger was the change of odor from rotten radishes / 'gas' to STRONG ODOR OF ROTTEN EGGS. I stupidly ignored this warning. Suddenly without any further warning: my nose started STINGING / BURNING UNCONTROLLABLY - NO MATTER HOW QUICKLY I RUSHED TO THE NEAREST WINDOW. Still the UNBEARABLE STINGING / BURNING WOULD NOT GO AWAY, OR EVEN LESSON IN THE SLIGHTEST!!! SEVERAL hours later the stinging / burning in my nose was tolerable and had almost gone - only to be left with a nasty cold that took at least a few days to get over. I could have only been exposed to the gas for a few minutes at the most - while I was transferring some aluminum selenide from one container to another. By the way - always store and handle aluminium selenide away from even air!!
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[*] posted on 25-9-2011 at 04:15


Quote: Originally posted by perry798  
Be VERY, VERY careful indeed when working with hydrogen selenide!!! I found out why - THE HARD WAY!!! By accident I exposed myself to a HIGH concentration of the gas. The first sign of danger was the change of odor from rotten radishes / 'gas' to STRONG ODOR OF ROTTEN EGGS. I stupidly ignored this warning. Suddenly without any further warning: my nose started STINGING / BURNING UNCONTROLLABLY - NO MATTER HOW QUICKLY I RUSHED TO THE NEAREST WINDOW. Still the UNBEARABLE STINGING / BURNING WOULD NOT GO AWAY, OR EVEN LESSON IN THE SLIGHTEST!!! SEVERAL hours later the stinging / burning in my nose was tolerable and had almost gone - only to be left with a nasty cold that took at least a few days to get over. I could have only been exposed to the gas for a few minutes at the most - while I was transferring some aluminum selenide from one container to another. By the way - always store and handle aluminium selenide away from even air!!


I know what you mean. I have a container full of aluminium sulfide. And not only is it sealed, stored with obnoxious amounts of desiccator, but its also wrapped in tape, covered with bubble wrap, contained in two ziplock bags and stored on the lowest shelf behind all the other containers. I'll find the courage to use it someday....
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