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Author: Subject: Hardware store chemicals - questions
freddurgan
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shocked.gif posted on 29-9-2006 at 19:06
Hardware store chemicals - questions


I went to my local hardware store and was pleased to find very accessible and useful chemicals.

I can get:
Toluene (bottle says 100% pure) for like 5 bucks
Xylene (unknown concentration)
VM & P Naptha (?? random alkanes?)
"Concentrated sulfuric acid" (I don't know the concentration)
Hydrochloric acid in like 20% concentration

I'm confused about sodium hydroxide. I found many products with sodium hydroxide in it, but at questionable concentration and other chemicals.

Do any of these not function well as lab chemicals? And why? Solutions?

Thanks!
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[*] posted on 29-9-2006 at 19:53


Look for the one that says 100% lye.



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[*] posted on 29-9-2006 at 20:27


All of these will ahve some impurities in them, how important they are depends of the use.

Xylene should be pretty pure, maybe some ethylbenzene. But as it's an ortho/meta/para mix, generally it's just used as a solvent and the other compounds that might be in it won't affect that use.

VM & P is just hydrocarbons, mostly saturated. There's a set of specifications on boiling range and what not, again it's a solvent.

Concentrated sulfuric acid seems to run from 80 to 95 percent. Sometimes it has other ingredients in it but they should be listed or implied with statements like "improved anti-corrosion formula", these are likely a lot less useful.

Typically it is brownish to almost black, this is generally traces of hydrocarbons and elemental carbon. That can be removed to some extent by heating the acid to boiling, and usually occurs during concentration if you need to do that.

Concentration to 98 percent is done by distilling off the water until the constant boiling temperature of 330 C is reached. For weaker acids just a simple open flask or dish will do, but once the concentration hits 80% or so then the vapour will contain acid as well and some sort of simple fractionation is wanted.

Concentrated sulfuric acid likes to bump when boiled, boiling stones and bits of broken pyrex help reduce this problem. But it means that you shouldn't heat the concentrated acid to near bolling in a open/wide-mouthed container, because it is going burp acid at you.

Hydrochloric acid typically has traces of iron in it, giving it a yellow-green tint. The 20% concentration is slightly less than constant-boiling, and doesn't fume nearly as much as the other common 30 to 36 percent acid. You can distill the 20% acid to remove impurities; if you do this with the stronger acid it will lose HCl gas until the strength drops to the constant boiling range. You can put distilled water in the receiver to absorb the HCl gas, if you measure it correctly you'' end up with the 20-21% acid.

Drain-cleaning sodium hydroxide will show up as everything from a water solution with potassium hydroxide, to nearly pure NaOH with small amounts of the carbonate and calcium or NaCl in it, to mixtures that are sold as being better at cleaning out drains. For most purposes small amount of carbonate, calcium, or chloride aren't going to matter, often this will be labled as 100% lye. The mixes are another story, usually aren't that useful.
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[*] posted on 1-10-2006 at 01:06


Regarding the sulfuric acid from drain cleaner, I suggest heating the stuff until a temperature that is likely to deactivate any buffers they have added, plus that will evaporate some of the water. The solvents can have their purity improved by distillation, especially if you have a Vigreux of fractioning column.



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[*] posted on 1-10-2006 at 02:02


The sulfuric acid drain openers do not have buffers in them. They may have corrosion inhibitors to protect the pipes, and surface agents to speed penentration of the plugging material by the acid. They also seem to have dyes and possibly other agents in them to make them look like something other than water, to make them look like stuff you don't want to touch.

The corrosion inhibitors may include inorganics like phosphates, these would not be affected by heating. Organic inhibitors are likely to be oxidised by heating the acid to near boiling, as are dyes and surfacants; these are not 'inactivated', they are oxidised to CO2 and water with SO2 being produced.

One MSDS listed 0,5% thiourea as the corrosion inhibitor., this would seem that it might release some H2S during heating.

Polyethylene oxide seems to be a common surfacant, 0,2 to maybe 1,0 percent; the higher concentrations will thicken the acid even though the surface tension and this 'wetness' is lowered.

US patent 5429764 is for a sulfuric acid based drain opener, and lists possible additives. Amount those are perfluoroalkyl sulfonates, which are not going to be easy to break down just by heating the acid; various other fluoronated additives are listed.

If you actually distill the acid, not just concentrate it, most inorganics will remain behind. If you can do that, and there seem to be much organics in the acid, adding some potassium persulfate to the acid before distilling (but after a preliminary boil) will oxidise the organics so that none carry over into the diistilled acid. However distilling sulfuric acid is not to be undertaken lightly, you need all-glass apperatus and can not use hydrocarbon grease on any joints. And it will be _hot_, 330 C boiling point.


Those in the US counting on getting their sulfuric acid from drain opener should read this. It appears that the request was turned down, but another may be in the works - I'm not sure if what I saw on the request refusal applied to this or a previous one.

http://cpsc.gov/pr/sado_moore.pdf#search=%22sulfuric%20drain...
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[*] posted on 1-10-2006 at 02:54


Quote:
Originally posted by not_important
adding some potassium persulfate

Uh, I think anyone needing to use drain cleaner as a source for H2SO4 will have even more trouble obtaining K2S2O8. If you're living in the US, someone on eBay does sell it. Elsewhere like Canada, good luck. You might as well tell us to make H2SO4 by diluting oleum.

[Edited on 1-10-2006 by Quince]




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[*] posted on 1-10-2006 at 03:23


I would assume his notion included Oxone as a potassium persulfate equivalent as well. But generally a little H2O2 is added (very carefully!) to the dirty H2SO4 if the only goal is to decolorize it and then concentrate it by heating only.
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[*] posted on 1-10-2006 at 03:39


Actually I tried a bit of 35% H2O2, but the original slight yellow tint was unchanged.



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[*] posted on 1-10-2006 at 03:43


Yellow? What's wrong with yellow? I was talking about the carbon and other black stuff in some hardware store H2SO4. A yellow tint says not much about the purity of a compound. If it only has a yellow tinge then you can even assume that it is quite pure and better don't mess with it unless you know it is not pure.
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[*] posted on 1-10-2006 at 04:24


So if not carbon etc., what's the yellow from? It's gotta be from something.



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[*] posted on 1-10-2006 at 07:43
Vacuum Distillation


I've used this for some of the more shitty H2SO4 drain cleaners like Roebic but
find it unnecessary for Rooto. Rooto does a great job on its own and doesn't have the
severe discoloration I've noticed in others. My next purchase of H2SO4 drain
cleaner will be the "Misty" brand. Supposedly it's as high as 93%. I'm currently searching
local janitorial supply houses for this one.




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[*] posted on 1-10-2006 at 14:05


Sometime in the near future I'm going to attempt to get a 750lb drum of 96-98%concentrated technical grade. Should be much better than the stuff sold as drain cleaner.

My plan is to repackage it and sell it by the liter with a minium order of a 4L case. I could sell larger quantities, but then it would have to go Hazmat which would eliminate any potential savings.

I'm going to try to keep the cost below $10 per liter.

My question is would anyone be interested?
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[*] posted on 1-10-2006 at 16:58


Can you ship to Canada?



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[*] posted on 1-10-2006 at 17:20


Quote:
Originally posted by Quince
So if not carbon etc., what's the yellow from? It's gotta be from something.



In general it is traces of carbon or carbon compounds, and/or iron. You can do a test for iron to if your particular source has iron or not. Larger amounts of carbon tend to go orange-brown, brown, brown-black, or used-automotive-oil black as the amount of carbon and carbon compounds goes up.
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[*] posted on 1-10-2006 at 17:27


Quote:
Originally posted by Nicodem
I would assume his notion included Oxone as a potassium persulfate equivalent as well. But generally a little H2O2 is added (very carefully!) to the dirty H2SO4 if the only goal is to decolorize it and then concentrate it by heating only.


The persulfate is what the more recent purification of reagents texts suggest. I've always used H2O2 myself, adding it drop by drop to the hot acid until it seems to have no more effect, then boiling for a bit to decompose any excess H2O2.

I think that H2O2 is no longer suggested because of the possibilty of explosion if too much is added at once, or added to cool acid which is then heated. With the organics they put in some drain cleaner acid, I would be careful using H2O2, get the acid hot first, keep the addition rate down and in small portions.

Adding H2O2+water to concentrated sulfuric acid is going to splatter and spit, best to do it in a flask.

Note the the stablisers in the peroxide are going to end up in the acid.
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[*] posted on 1-10-2006 at 18:25


Quote:
Originally posted by Quince
Can you ship to Canada?


Shouldn't be too much of a problem.

I can send it anywhere UPS ground can go.
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[*] posted on 1-10-2006 at 18:45


Uh oh... UPS over the border is a no-no. They charge a ludicrous brokerage fee (separate from the customs charge itself). US Postal Service is the way to go...



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[*] posted on 1-10-2006 at 20:32


See that'd be the catch right there. You can't ship concentrated sulfuric acid via USPS.

If they caught me mailing that my ass would be grass.
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[*] posted on 2-10-2006 at 00:51


What about FedEx or Purolator?

UPS may be worth it for say 10 L and up.

[Edited on 2-10-2006 by Quince]




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[*] posted on 2-10-2006 at 11:34


DHL used to be pretty good about chems - dunno about now.
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[*] posted on 7-10-2006 at 00:54


Kinda curious, Is there an easy way to get ahold of dilute sulfuric acid, aside from buying the concentrated stuff and diluting it? I've heard that there's some special way to dilute strong acids without hurting yourself, and doing it the wrong way = bad things happen. So I'd prefer, if i can, to find a source of more dilute (say 20-50%) H2SO4, that's still relatively pure (that is, just H2S04 and water).

But maybe I ask WAY too much...




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[*] posted on 7-10-2006 at 03:43


Automotive electrolytic battery.



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[*] posted on 7-10-2006 at 09:12


Some drain cleaners. Many have at least a significant amount of H2SO4, and there are several that are essentially the concentrated acid, maybe with a few surfactants.
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[*] posted on 7-10-2006 at 09:35


His point was he didn't want to spend on concentrated acid. H2SO4 is only useful for a drain cleaner when it's concentrated, so any drain cleaner he'll find will not be dilute.



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[*] posted on 21-11-2006 at 04:50


If you need to dilute it indigofuzzy just remember to add the acid to water rather than the other way around, and try not to breathe any fumes.
Where I live it's easier to obtain a semiautomatic weapon than to get pure H2SO4. The drain cleaner is mixed with copious amounts of 'morning fresh' or similar :P
I'm not above emptying an old car battery to get sulphuric.
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