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blogfast25
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Quote: Originally posted by Zyklonb  | | 98% nitric acid will burn within 5 seconds, and will leave yellow stains no matter how fast you wash it off. It catches all OTC gloves on fire within
10 seconds, so wearing no gloves is probably better than any at all. |
You have evidence for this 'catches all OTC gloves on fire within 10 seconds'? Sounds exaggerated to me, it's not THAT strong an oxidiser. A reputable
link would be nice...
Even 35 % nitric will leave yellow stains on skin fairly quickly but they're only stains and fade to nothing over a week or so. It's very superficial
attack of the epidermis only.
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Zyklon-A
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Hmm, I probably spoke too soon. No, I don't have evidence. The only gloves I can find locally are Latex or Nitrile - both of which catch on fire
spontaneously upon contact with fuming nitric acid.
https://www.youtube.com/watch?v=aBVdGGml6bU
[Edited on 21-5-2014 by Zyklonb]
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macckone
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| Quote: Originally posted by blogfast25 | | Quote: Originally posted by Zyklonb | | 98% nitric acid will burn within 5 seconds, and will leave yellow stains no matter how fast you wash it off. It catches all OTC gloves on fire within
10 seconds, so wearing no gloves is probably better than any at all. |
You have evidence for this 'catches all OTC gloves on fire within 10 seconds'? Sounds exaggerated to me, it's not THAT strong an oxidiser. A reputable
link would be nice...
Even 35 % nitric will leave yellow stains on skin fairly quickly but they're only stains and fade to nothing over a week or so. It's very superficial
attack of the epidermis only. |
The three common OTC gloves are nitrile, latex and some
kind of clear plastic for food service that isn't identified.
As opposed to mail order that are more resistant and
designed for chemical use (butyl and pfa for example).
Those three OTC gloves do react 'vigorously' with RFNA and
are too thin to provide protection. The thicker dishwashing
gloves also react (latex). They do 'smoke' almost immediately
but I wouldn't call it 'catching fire' although they will combust
and don't provide any protection given RFNA.
Hardware stores sometimes carry other varieties of gloves as
do cleaning supply places but they aren't as readily available.
I guess it depends on how you define OTC and 'catch fire'.
Someone should probably do an experiment with video.
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macckone
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Speaking of sulfuric acid and combustion, has anyone tried
burning MSM (Methylsulfonylmethane aka dimethyl sulfoxide).
It is much more readily available than sulfur or sulfuric acid
drain cleaner or even battery acid in a box. It is available
at practically every health food store. In theory it could
be used like sulfur (although more expensive) but it isn't
as flammable and may not burn cleanly.
I haven't found anything in literature other than on the MSDS
that it yields sulfur dioxide and carbon monoxide when burned.
Any literature references or practical experience would be helpful.
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blogfast25
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Zb:
Well, I didn't expect that, TBH.
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Zyklon-A
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When I first burned my hand with fuming nitric acid, my mom asked me why I wasn't wearing gloves - rather than tell her, I showed her. All it took was
about 5 drops of RFNA on a Nitrile glove. (They caught fire and cracked the glass dish from the heat). She was quite surprised to say the least.
Ok I just got some of those annoyingly large clear plastic food grade gloves. When I get home I'll test them against 98% sulfuric acid and RFNA. I
doubt they'll catch fire, but they will almost certainly get holes burned through them. (With FNA, not con. sulfuric acid).
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aga
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The drain cleaner + peroxide worked.
Now have some sulphuric acid at last, whch is clear and fairly pure.
Certainly purer than the garbage iwas playing with before.
My hotplate can't reach 300 C +, so i stopped after about 30 minutes of what i believe was 'fuming'.
Titration with NaOH solution shows it to be about 12 Molar, which his good enough for me, for now.
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Zyklon-A
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| Quote: Originally posted by Zyklonb | | When I get home I'll test them against 98% sulfuric acid and RFNA. I doubt they'll catch fire, but they will almost certainly get holes burned through
them. (With FNA, not con. sulfuric acid). |
Incredible news! I just tested the "annoyingly large clear plastic food grade gloves". I made a flat
surface by placing the gloves over the mouth of a beaker. Then I added several drops of ~97% nitric acid. Nothing happened! 15
minutes later the gloves were not even etched. Then I added several drops of 98% sulfuric acid. Still nothing. I'm very amazed that the crappy food
grade gloves managed while the "ultra chemical resistant" gloves all failed.
Anyway, I hope this answered your question aga!
[EDIT] Here's the same brand of gloves I used: http://www.anything4restaurants.com/products/textra-textured...
They are called Textra ® Cast poly gloves. By FOODHANDELER ™.
[Edited on 21-5-2014 by Zyklonb]
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blogfast25
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| Quote: Originally posted by aga | My hotplate can't reach 300 C +, so i stopped after about 30 minutes of what i believe was 'fuming'.
Titration with NaOH solution shows it to be about 12 Molar, which his good enough for me, for now. |
Concentrated H2SO4 is about 18 M. Are you sure what you saw was real fuming and not just water vapour (steam) coming off? At 70 % I didn't see
anything that qualifies as fuming.
Do a density measurement? Weigh a small measuring cylinder (w<sub>0</sub> . Then weight it full with water (w<sub>1</sub>. Then weight it full
with acid (w<sub>2</sub>.
d<sub>acid</sub> = (w<sub>2</sub> - w<sub>0</sub>/(w<sub>1</sub> - w<sub>0</sub> (density relative to
water)
[Edited on 22-5-2014 by blogfast25]
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blogfast25
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Zb:
It's perhaps less surprising than you think. These gloves are almost certainly made of LDPE and that is very chemically resistant. HDPE is routinely
used for permanent storage of 70 % nitric acid and 98 % H2SO4. LDPE and HDPE are chemically almost identical, but HDPE is slightly more crystalline
and therefore mechanically tougher.
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Zyklon-A
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So I guess my question is, why don't chemical resistant gloves imploy such plastics? Or at least mention in papers (like the one I linked) that those
gloves do exists and are suitable for handleing fuming nitric acid.
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blogfast25
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One possible explanation is that both latex (usually NR; thus poly isoprene, or SBR; thus poly butadiene styrene) and nitrile (more scientifically
acrylonitrile butadiene rubber, aka NBR) contain a lot of double bonds, which obviously makes them prone to attack by oxidisers.
These rubbers would normally not be recommended as 'highly chemically resistant' although nitrile does have the advantage of being quite resistant to
paraffinic and aromatic solvents due to its polarity (hence the use of NBR in fuel lines, for example).
LDPE, HDPE, PP and EPR are fully saturated and well known to resist most chemical attacks well.
http://en.wikipedia.org/wiki/Nitrile_rubber
http://en.wikipedia.org/wiki/Synthetic_rubber
[Edited on 22-5-2014 by blogfast25]
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blogfast25
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According to one source, adipic acid (hexanedioc acid) can be prepared by oxidative cleavage of cyclohexene with nitric acid, an example of oxidation
of a double bond with nitric acid.
Since as oxidations are usually strongly exothermic, reaction of a material plentiful with double bonds with fuming nitric may be sufficiently
exothermic to actually ignite the material (and combustion in air to take over).
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macckone
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Interesting that the food grade gloves survived the nitric.
I guess different brands are going to give different results
based on what they are made of.
Still curious about combustion of MSM though.
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aga
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Gay, Straight or just MSM Curious, experimentation is the way forward !
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macckone
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I don't currently have a hypothesis because of the lack of literature.
It isn't scientific experimentation without a hypothesis.
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blogfast25
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Garden variety sulphur is even more available and will be cheaper per g of SO2 generated.
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Fulmen
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This seems to be the most current thread on concentrating H2SO4, so I'll try here rather than starting a new.
I just tried boiling in some SA (needed to make nitric acid from SA and calcium nitrate), and it worked much better than expected. My hotplate (Ikamag
RCT) is limited to appr 300°C, so I just let it run until it stopped boiling. According to this: http://www.generalchemical.com/assets/pdf/Sulfuric_Acid_Wate... you should get huge losses long before you get anywhere near 90%, yet I got a
density > 1.8 with only mildly unpleasant vapors coming off.
And then it struck me. I started with 250ml of spent battery acid in a 300ml EM-beaker, by the end I was down to appr 50ml. Considering the high
temperature and almost empty beaker, wouldn't it act like a crude rectifying column? The Liquid/vapor equilibrium is a bit odd compared to simple
mixtures like water/ethanol, am I wrong in assuming that it makes SA very easy to distill to high concentrations?
[Edited on 12-11-14 by Fulmen]
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bbartlog
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MSM seems unlikely to me to be a good source material for anyone who wants well-defined products. Too much carbon and hydrogen in the mix. I guess if
you were careful to provide excess oxygen and high temperatures you could at least avoid contaminating your sulfuric products with unburned carbon
products aka soot, but you would still end up with added water as one of the products of combustion.
The less you bet, the more you lose when you win.
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greenlight
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Fulmen, Sulphuric acid that is intended for use in batteries is very dilute to start so that may explain why you were only left with 50ml.
Using an Erlenmeyer flask (if that's what you mean by EM flask) I think there would be some condensation on the sides of the flask.
You say you used a 300 degree max hotplate and just turned it on till boiling temp. The boiling point for concentrated Sulphuric acid is 337 degrees
Celcius so if you had the hotplate turned up all the way and you shot near that temperature maybe some of the acid decomposed too.
When I used to concentrate 50% Sulphuric acid with heat I used to do it in a glass saucepan or glass heat resistant dish with a thermometer in the
dilute acid. I heated the acid to just past 100 degrees Celcius usually to about 110 to 115 degrees Celcius, just above the BP of water. This way
there were no nasty fumes from the acid boiling when concentrating and I didn't need to bring the acid to a boil at all.
You can tell when it is concentrated because slight white fumes start to come off and the colour changes to much darker. If you hold a piece of flat
glass like the bottom of a large beaker or a watch glass over the heating vessel for like 10 seconds you will notice the water from the acid mix
boiling off and condensing on the glass making it foggy. This is another way to check if it is finished because once it stops, no more water is
coming off and it is concentrated.
[Edited on 12-11-2014 by greenlight]
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Fantasma4500
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i recall 50% H2SO4 is called ''tower acid''
some time back i found people on ebay selling 50% H2SO4 for swimming pools use, it was pretty large amounts, and surely they are still trading it
i guess for concentrating it down, if you are lucky you could perhaps get some high temperature resistant glass tube and fill with some sort of a
substrate with V2O5 on it, and run SO2 / air through it
yields will be increased with dry air
then run through H2SO4.. the SO3 formed should remove water from the H2SO4 and may form oleum if let arise in concentration past 98%
one guy on SM talked alot about a machine like this he had he used alot, but he never got to post pictures about it, sadly.. he said it was full
glass, and SO3 through H2SO4 is ofcourse a preferred method for concentrated sulfuric acid, considering SO3 everywhere as the alternative
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Fulmen
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The reduction in volume was to be expected, and I also assume there has been some decomposition as it turned yellow at the end. The interesting bit
was how concentrated the result seemed to be with very little acid vapors. Judging the fumes is hard as I do this outside at windy 40-50F temps, even
water produces a white fog. I'm going to run a few more batches and see if I can't do some temperature measurements of both the liquid and vapor
coming off and perhaps a simple titration.
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Fulmen
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Crud, my only suitable thermometer has died, so no luck there. But a sample of the concentrated acid started freezing at appr 9°C (40F), which should
put it in the 80-90% range. Not bad really, considering the setup. This warrants further experimentation.
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vmelkon
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| Quote: Originally posted by Fulmen | | Crud, my only suitable thermometer has died, so no luck there. But a sample of the concentrated acid started freezing at appr 9°C (40F), which should
put it in the 80-90% range. Not bad really, considering the setup. This warrants further experimentation. |
I suggest measuring the density. You can buy a cheap digital scale for 10$ on ebay. Mine goes from 0.01 g to 500.00 g but precision is +/- 0.03 g.
There is another one that does 0.001 g to 50.000 g but.... how good is the precision on these things.
Also, get yourself a good graduated cylinder. Preferable a thin one. Or get a burret (I have a bunch with accuracy to 0.02 mL or something like that).
Signature ==== Is this my youtube page? https://www.youtube.com/watch?v=tA5PYtul5aU
We must attach the electrodes of knowledge to the nipples of ignorance and give a few good jolts.
Yes my evolutionary friends. We are all homos here. |
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Fulmen
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I have scales, the problem is to measure volumes accurately. I think a weight-based titration will be the best route, I'll see what I can whip up.
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