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The_Davster
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[*] posted on 19-8-2006 at 16:21


I recently got some acids in bulk(bulk to me as I do stuff pretty small scale) but am out of storage in the lab cupboard.
For nitric, sulfuric and hdrochloric I plan to wrap all the caps in teflon tape, place the 2.5L jug in a plastic bag which will be sealed well. Then place this bag in a plastic drum with some bicarb in the bottom to react with any vapours. Have to do all this as the temp in the garage ranges so widely that storage of an acid like nitric would cause excessive decomposition. These drums will then be in my closet as I am running out of storage space elsewhere, and as such I can't have much acid vapour in the room I sleep in.
Thoughts?

I once had all my chems in my room for one night as a service person was coming, day after I had a sore throat.

EDIT: should mention this is for long term storage, I won't be opening and closing these acid bottles much if at all, I have other acid in the lab for use.

[Edited on 20-8-2006 by rogue chemist]
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[*] posted on 19-8-2006 at 18:19


I have found muriatic acid (37%HCl) to be a particularly tough chemical to store. I have it stored in its original plastic bottle placed in a 5-gallon plastic bucket for double containment. A while back I noticed that steel surfaces in my poorly vented shed were rusted. So I bought a plastic funnel that fit up to the bucket lid bung tightly. In this funnel I placed some fiberglass insulation as a porous support then covered this with 1-2 cm of NaHCO3. This serves as a breather filter for the bucket while hopefully not letting any HCl gas vent into the shed.

I had iodine crystals in a ground glass stoppered jar and thought they were being contained. But the weather this summer was apparently too hot and I found a yellow deposit/reaction on the shelving. I have sent for some teflon lined 125mL wide-mouth jars which will be tried next. In the meantime it is stored in my freezer. I should get some sodium thiosulfate as a backup as recommended by Woelen.




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The_Davster
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[*] posted on 19-8-2006 at 18:54


Well as HCl has a melting point of -25C, I should be able to store it in the garage for most of the year minus the one or two weeks a year it gets down to -30. I don't think the garage would get as cold as the outside. Nitric must be stored indoors as it does not handle temperature variations well, especially hot summer weather. Sulfuric being nonvolatile can go inside easily, and since it freezes at -4 should not be outside at all.

Hmm, I could only find 5 gal buckets, kind of big for a 2.5L jug of acid, but If I can't find anything else....

As for iodine, I grabbed an empty bottle once used for iodine out of my universitiy's trash and put my iodine in it. I wrapped a kleenex around the lid to see if the iodine excapes, and so far the kleenex is pure white. The lid did not look any different from normal lids... I keep the bottle of iodine in a ziplock baggie as well.
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[*] posted on 20-8-2006 at 09:43


what about phenol? I read that it melts at +41/45 C, but once I kept it outside for about 10 minutes at 35 C and it turned liquid, when it's not in use it stays in the freezer. At what temp. does it actually melt? Anyone with the same problem?



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not_important
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[*] posted on 20-8-2006 at 09:46


A rather small amount of water noticeably lowers the melting point of phenol.
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woelen
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[*] posted on 20-8-2006 at 13:04


I have some 90% phenol (the rest is water) and this is liquid, also at temperatures of 10 C. Phenol tends to become red quickly, when oxygen can come in contact with the liquid. Even in a very well closed bottle, when it is opened a few times and closed again, then it turns red already. It appaently is very sensitive to aerial oxidation and the oxidation products are very strongly colored.

I would suggest to take a very small part of the phenol from its original container and use that for experiments, and the original container then is stored in a very well closed larger container, with a plastic bag around it. In this way, only the small amount, intended for immediate use, is exposed to oxygen every time when it is opened, your stock then remains good and only is opened once, when your small amount is used up and needs to be refilled.

I use this tactic for many air-sensitive chemicals (e.g. Na2S.xH2O, VOSO4.xH2O, NaCN, CuCl, phenol, aniline, ...).




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The_Davster
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[*] posted on 20-8-2006 at 20:06


Luckily solid phenol does not suffer from the oxidation problem. I have seen literally dozens of old phenol bottles with phenol in perfect condition, just sublimated and deposited on the sides of the container.

NaCN air sensitive? What hydrolysis with the water in the air to HCN? Always though it stable, but I do not have any.
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[*] posted on 20-8-2006 at 20:20


Doesn't cyanide oxidize to cyanate (-OCN)? Hence bleach somewhat deactivating cyanide..

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not_important
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[*] posted on 20-8-2006 at 20:37


Quote:
Originally posted by rogue chemist

NaCN air sensitive? What hydrolysis with the water in the air to HCN? Always though it stable, but I do not have any.


CO2 will displace HCN from soluble cyanides.
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woelen
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[*] posted on 20-8-2006 at 22:42


Yes, NaCN is very air-sensitive. I have my stock amount in a double boxed container, and that still is OK. The 20 grams or so, which I store in an ordinary plastic bottle already has decayed quite a lot. It slowly is converted to Na2CO3. I noticed this, because, when I add pure NaCN to cold dilute HCl, then no bubbles are formed (all HCN remains dissolved in the liquid). When I add the decayed NaCN to dilute HCl, it starts bubbling quite vigorously. I did not smell this gas :o :D, but I'm quite sure that must be CO2 (of course, contaminated with HCN).

NaCN is hygroscopic and the humid solid in turn absorbs CO2, forming H2CO3, which in turn expells HCN from NaCN, itself being converted to NaHCO3 and/or Na2CO3.

[Edited on 21-8-06 by woelen]




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not_important
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[*] posted on 18-9-2006 at 22:58


There are several threads where posts related to sealing containers and/or chemical resistance show up. I hink that there is some important information being omitted.

Teflon products such as tape come in a range of densities, with the lower densities being more porous. A porous tape may not be harmed by a reagent, but still allow the reagent to diffuse through it. Densities run from 0.35 - 0.4 (the white tape) on up to 1.6 for some gas line tapes, and 2.1 to 2.2 for solid Teflon.

There are several common types of teflon tape for plumbing use. Common colour coding for these is

White - single density. Small pipes and temporary installations
Yellow - double density. Often used on gas fittings
Red - triple density. For larger pipes and higher pressures (but still home/commercial type installations)
Green - oil free for oxygen plumbing.

The light weight white tape really works best covering the threads, not as an external seal. When used to cover joint/cap threading, stuff attemping to leak through must travel through the width of the wrapped section; when used as a wrap around the outside of a bottle cap stuff leaking through only has to go through the thinkness of the tape. Even several layers of tape is nothing compared to the tape's width. The white tape also is depending on the hydrophobic nature of Teflon to keep back water, even though it is fairly porous. The red tape works pretty well as the external seal.

Extra thick tape makes good cap liners, for both protecting the cap inself and forming a seal with the top of the container; when the teflon flows from the pressure of the cap on the container, the extra thickness still protects the cap at that point and allows the formation of a slight raised ring of teflon on either side of the container lip - sort of O-rings.

One, but not the only, tape that seems to work well as a cap liner is C.S. Hydes 'Fat' Teflon tape. The sample I saw used had silicone based adhesive, however it appears that currently they only offer an acrylic adhesive form of the 'Fat' tape. It comes in a range of thicknesses and widths up to 12 inches. The tape is uncoloured, just plain, pure Teflon. It is not cheap, unlike the white Teflon tape from hardware stores, but the 3 mm stuff seems to do a good job at holding corrosive reagents in place. A piece of metal tubing can be honed on one end to make a circular cutter for punching out disks of tape.

Perhaps interested people could pool funds and share rolls, as I doubt an individual would need all of even a 5 yard roll for lining bottle caps. They do sell foot square sheets, which might be a good fit for the home experimenter.

Ah, URL
http://cshyde.thomasnet.com/viewitems/tapes-with-psa/fat-ptf...


A side note. The more porous tapes have been used as catalyst delievery and recovery systems. A catalyst with a fluorocarbon 'tail' is applied to plain non-adhesive low density Teflon tape. When placed in a reaction mixture that heated, the catalyst diffuses out into the solvent or neat reactant; higher temperature increases the fluorocarbon solubility. After the reaction is done, cooling the mixture cause most of the catalyst to migrate back into the pores in the Teflon tape, which is easily recoverable.

[Edited on 19-9-2006 by not_important]
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[*] posted on 22-7-2009 at 08:24
conc acid/solvent storage


Hi i read somewhere (this site i think but i can't find it now) that it's best to store acids/solvents in a fridge. What i'd like to know is should it be separate fridges ?
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[*] posted on 22-7-2009 at 08:40


I would always store acids seperate from solvents, just because it's good lab practice. I don't think it's really a big problem unless there is a speceific incompatibility, i.e. nitric or perchloric acid should not be stored with oxidizable/highly flammable solvents such as diethyl ether.



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[*] posted on 22-7-2009 at 08:55


Thanks, Looks like i'm in the market for another fridge :D
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[*] posted on 22-7-2009 at 09:00


If you weren't too lazy to search you would find the many, many threads here on chemical storage and find a better answer to your question.

It's rude (and lazy) to continue your practice of starting new threads when an existing one would answer your question.
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[*] posted on 22-7-2009 at 09:30


I probably wouldnt store flammables in a fridge; I seem to recall something about an explosion hazard due to un-isolated electricals.
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[*] posted on 22-7-2009 at 11:14


entropy51 As i said i couldn't find it.

DJF90, Interesting point, but would the temperature inside the fridge not stop the solvents from giving of vapour,and reduce the chance of ignition by a spark? also what do you mean by un-isolated ?
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The_Davster
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[*] posted on 22-7-2009 at 12:03


Explosion proof fridges have sealed electronics to prevent components that could spark from igniting vapour.

I would just use secondary containment to separate nitric from oxidizable materials. For the usual amount of chemicals home chemists have I would find 2 overkill. I would not even bother with sulfuric, perchloric or non-volatile acids in there. No vapour pressure worth worrying about.

But I woud also use an explosion-proof fridge if I was storing acids, acid vapour is hell on exposed electronics...

[Edited on 22-7-09 by The_Davster]




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[*] posted on 22-7-2009 at 12:39


Thanks this is the bit i was looking for.
That makes scene,but i don't think i've seen an explosion proof fridge for sale or are all lab fridges explosion proof?
So to summarise 1, insulate/isolate or remove potential spark hazards 2, keep both in the same fridge but separate the nitric acid.
I also have some 37% hcl to store could this go in the fridge or should i use Magpie's system?
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[*] posted on 23-8-2009 at 13:00


It's funny how I don't know some threads on this forum ever existed until someone brings it about my attention. Some of my own thoughts on chemical storage and what I do. I have seen some dissapointing mixing of chemicals when it comes to storage (having chemicals all together in one area undivided and uncategorized), but I think there is also people here who are so cautious and aware that chemical storage saftey far exceeds how the general public stores its materials.

I don't have a lab per se. I unpack and then repack every time I use something. Compatibles with compatibles (usually like with like, but it doesn't work with NH4 salts and oxidizers, or trichloroisocyanuric acid and hypochlorites). Ammonium salts with ammonium salts is generally not a problem and is what I do.

The bulk of my chems are just household stuff, so no major concerns on my part. Anything a bit more unusual, like the near conc. HNO3 is in a brown glass bottle. The acid is packaged in styrofoam in a cardboard box it came in. If it must be stored, store perchloric acid away from most things else. Wood cabinets, cardboard, etc. are a no no. PTFE container in a metal cabinet would be ideal.

Kilogram sacks of sodium bicarbonate in case of acid spills is good to have nearby (also maybe for small fires). NH3 can be used against a variety of vapors (SO2, NO2, HCl, HCOH, COCl2, etc. with caution (read up on hazards) also against Cl2 and dimethyl sulfate). For bases, vinegar bottles. At least one fire extinguisher present on the same level the chemicals are. I also have several gallons of water ready in case of a spill or emergency. You could opt for a washing station if you are a true labcoater.

I think if I want to be assured in storage I imagine if a light earthquake would happen, how chemicals could mix, what could happen and then take steps to store them separatley. Chemicals which cause me too much concern are disposed of. Chemical lockers or cabinets aren't a bad idea, especially with kids and if you have a lab.

When I lived in an apartment, the chemicals were in a remote storage facility, since experimentation was off limits in apartments. In the house, the basement is good. Nice and cool, not too much sunlight, etc. Good inert concrete environment.
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[*] posted on 23-8-2009 at 13:06


How does TCCA react with hypochlorites? on the packet of TCCA there are many warnings never to mix it with 'unstabilised chlorine' a.k.a. calcium hypochlorite, but i have never worked out actually what they would do when mixed...
any one know?
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[*] posted on 23-8-2009 at 13:17


I once tried that reaction and I can say to you, it is scary!

I treid mixing one gram of TCCA (crushed) with granulated calcium hypochlorite. The dry powder mix does not react. Then I added a drop of water. Soon after adding the water, a violent reaction occurs. First, the stuff becomes yellow and the very recognizable smell of NCl3 appears. After that, the material starts bubbling very vigorously and a lot of heat and choking gas is produced. Luckily the stuff did not explode.

I tried this reaction, because on a dutch chemistry forum, somwone posted a big warning. This man (who did not know anything of chemistry, but has an indoor home pool) mixed Na-DCCA (which is TCCA with one chlorine atome replaced by sodium) with calcium hypochlorite, kilo wise. He did not know of the dangers, he just replenished his container of pool chlorine with more pool chlorine. He intended to use this mix as a slurry and add this slurry to the water in the swimming pool. When he added some water to he mix, the mix started bubbling and the mix became dark (charring, due to the intense amount of heat produced in the reaction). A lot of toxic gas was released. This man managed to get outside, but he had problems with his lungs for many days. His dog did not survive, this animal was killed in the toxic gas inside the house.

I actually was quite shocked when I read this story and initially I hardly could believe it. But when I tried the reaction on a gram scale myself, I was convinced. In the Netherlands there is no warning at all on the label of the swimming pool chlorine bottles that it should not be mixed with swimming pool chlorine of another type. It was the same brand, and the bottles looked the same. The only difference was that the one bottle tells 68% active chlorine, calcium hypochlorite, and the other says 60% active chlorine, sodium dichloro isocyanurate. But these are the small letters, the main text on both bottles was "granulated chlorine shock treatment".




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[*] posted on 23-8-2009 at 13:26


Quote: Originally posted by woelen  
I actually was quite shocked when I read this story and initially I hardly could believe it. But when I tried the reaction on a gram scale myself, I was convinced. In the Netherlands there is no warning at all on the label of the swimming pool chlorine bottles that it should not be mixed with swimming pool chlorine of another type. It was the same brand, and the bottles looked the same. The only difference was that the one bottle tells 68% active chlorine, calcium hypochlorite, and the other says 60% active chlorine, sodium dichloro isocyanurate. But these are the small letters, the main text on both bottles was "granulated chlorine shock treatment".


No warnings? WOW, they are literally all over the bottles of pool chemicals you get here;

'Do not mix pool chemicals'

'Do not mix unstabilised chlorine with stabilised chlorine'

'Mixing pool chemicals generates toxic gasses (chlorine)'

... the list goes on and on...
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