Sciencemadness Discussion Board - Preparation of anhydrous AlCl3 in DCM - photos

Preparation of anhydrous AlCl3 in DCM - photos

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blogfast25 - 30-8-2010 at 06:50

I think I know not only which bottles you're talking about but where you're likely getting them. If it's not toolstation.com, have a look; order two before 6pm and they'll turn up on the doorstep the next morning, for free. I buy tons of stuff from there, my TLC scratcher was from there... £2.05.

The low yield from the generator could be the 3% of water helping absorb some of the hydrogen chloride before it ever leaves the generator. The table salt will have yielded so poorly due to the moisture content, I expect (as using diluted sulphuric does). This is why I was using laboratory grade anhydrous calcium chloride, among other reasons; like the doubling in moles of gas I could get from the same volume in the generator. I mentioned these points a few times earlier.

If you're just using a tube stuck into some water, you'll be loosing a fair amount of gas to the atmosphere; the test is effectively not only measuring how well you can produce it, but also absorb it.

Never heard of toolstation.com before but I have now! Mine was indeed 'Knockout Toilet and Drain Cleaner' from Barretine, about a pound dearer, IIRW. But I got them from the local hardware store around the corner. As I stated, they [Barretine] seem to sell both the 50 w% and 94 - 95 w% grades. Don't get confused.

Anything else from toolstation you'd especially recommend: ;-) ?

As regards some HCl being absorbed into the moisture in the reactor, including moisture on the kitchen NaCl, I'll calculate (well, estimate) that and have a run with dried NaCl.

As regards losing some HCl to the atmosphere, no way: the target solution concentration was only 0.5 M (this way I could titrate it directly). No bubbles actually reached the surface, in fact no bubbles ever leave the wash bottle tube: instead a 'permanent small bubble' forms and the HCl is absorbed immediately into the water. It's a very efficient gas phase/liquid phase exchange system.

If I understand well, your HCl bubbles through the conc. H2SO4 dispenser, right?

peach - 30-8-2010 at 08:20

Toolstation is John's mecca, I seriously went through a phase of reading the catalog like a bible, carrying it round with me. They have xylene, spirits, other bits and pieces, but nothing fantastic chemical wise. The sulphuric is the most useful thing. They probably have caustic soda as well.

Check for a local store, or sign up for the monthly catalog on the site. The stores work like Argos, you fill out a little card, get a free hot drink from the vending machine and wait for them to bag the bits (which takes minutes, it's all on big racks behind them). There's tons of stuff in the catalog you might find handy for lab type work. IP66 sealed switches to avoid solvent fires, sticky warning signs, a ton of couplings, wiring, plumbing and other bits, chemically resistant industrial paints, so on. They're dirt cheap as well, cheaper than the Screwfix and other catalogs, sometimes only by 10p, but it all adds up. B&Q isn't in the same domain. They sell to the public, they just look like they need a trade account.

I think moisture in the acid or salt has a lot more of an impact than people think. For example, using diluted down sulphuric will kill the yield. I expect it wouldn't take a lot to start bending the results quite far from where they should be.

You're right about the absorption, provided it's not actually bubbling, it can be caught well. That, however, combined with the above suggests a few percent of water hanging around in the generator could be skewing things up on your yields.

For truly anhydrous work, my wash bottle full of suspiciously jelly looking material is demonstrating that too much moisture and possibly sulphuric is leaving standard generators. As is Watson confirming the activated carbon I thought I may need.

Until I received back that gel looking result, I'd assumed a generator on it's own would be fine. Everyone else goes with the simple option and with 95 - 98% sulphuric and anhydrous salt in there, I was sure moisture wasn't going to be an issue from that aspect. But it obviously has got through, as I was taking extreme amounts of care in setting that up (distilling solvents from drying agents, porting it through tubes so it never touched the atmosphere, baking the glass).

From now on, all of my anhydrous work relying on a gas generator will feature a 98% sulphuric tube and active carbon to remove the entrained sulphuric.

The black art of safe, reliable, pure reactive gas handling.

[Edited on 30-8-2010 by peach]

blogfast25 - 31-8-2010 at 08:15

Another HCl generation experiment was carried out. This time 15 ml of 94.6 w% H2SO4 (about 0.25 mol of H2SO4) was reacted with about 60 g of crushed CaCl2 flakes, that is about 5 times the stoichiometric amount for the first displacement, in an oven dried reactor.

Experimental conditions as above. Yield obtained was 64 % for 1/2 CaCl2 + H2SO4 --> HCl + 1/2 Ca(HSO4)2

In reality the yield should have been slightly higher:

• small leakage at the reactor/tube bung noted
• reaction not fully ended, small amounts kept evolving but not really worth recovering
• only about half of the CaCl2 was in contact with H2SO4: partial dissolution, foaming and caking caused about half of the salt never to see any acid.

In reality to make a HCl generator that squeezes every drop of HCl out of your resources (the theoretical 36 mol of HCl per liter of conc. H2SO4) I believe one needs:

• some excess of salt
• good mixing of salt and acid
• high heat

Peach, there's no Toolstation near me, but I'll use Tinkerwebs.

PS: I did have a first (in a long time) small conc. H2SO4 spill while dispensing the 15 ml. Some of it ended up on two ungloved fingers. I ran for the running water, washed it off and suffered no consequences, not even discolouration. That thick skin of mine must be doing something...

[Edited on 31-8-2010 by blogfast25]

peach - 31-8-2010 at 13:48

I think flame drying it, whilst being a good idea for precision, is going to be swamped (heavily) by the 3%+ of moisture in the sulphuric. Can you redistill at high temperatures with things like H2SO4? If not, I'll try repeating the test when I distill some more sulphuric, which will be as soon as BEN-jar-min gets back to me about my glass.

The sulphuric does indeed take ages to fully cover the salt, especially if it's not powdered to fine dust. And it takes a long, long time for the reaction to fully stop. I said in another thread, I've left generators out in the rain for three days and they've still been fuming when it came to rinsing them. Given how long it goes on for, there may be some value to that extra fuming.

Heating to around 200C will push the first stage through to the end quicker. Heating over that for the secondary product results in more gas but also goo in the flask, and the cake is annoying enough.

Given the cost of the reagents, I just add some extra to the generator.

I now have a big cold trap at my disposal, so I have considered a.) producing liquid HCl(g) and dripping it onto the aluminium or other reactions as I want it, b.) the 'bomb' route. b.) is still in the very important R&D stages.

Here's a video I made a while ago... what will 35% Piranha mix do to my hand?

There is a more amusing video of me huffing hydrogen chloride gas, to illustrate the involuntary coughing it produces, hiding on the hard drive. It may appear sooner or later.

[Edited on 31-8-2010 by peach]

DJF90 - 31-8-2010 at 15:20

Nice video peach, I feel sorry for your hands and sink!

ScienceSquirrel - 31-8-2010 at 16:27

I have a a pair of 120 litre fermenters that I am running back to back to make beer.
I regularly wash them out with trisodium phosphate, potassium hydroxide, acid peroxide, etc to strerilise the surfaces and remove staining.
Would I stick my hands or anything else in these solutions?
No, you must be nuts to butter acid Piranha on your fingers :-(

Sedit - 31-8-2010 at 17:02

Yup because it shows if we aint dead yet these layman need to stop stressing when then smell bleach and think there being poisoned.

peach - 31-8-2010 at 17:16

Quote:

I have a a pair of 120 litre fermenters that I am running back to back to make beer.

I've done 210 in one. And didn't use anything to clean or sterilize it other than a kettle full of hot water.

But I'm drifting waaaaaay off AlCl3, a trait I'm attempting to curb.

Quote: Originally posted by entropy51

Could it possibly be Self-harming

It could be if it did any harm, yep...

You guys have issues. You've just seen me with it on my hands for minutes, then the results the day after. Absolutely nothing.

Back to yar scare mongerin', arrr.....

entropy, I made that video thinking of you, thinking "shit, he's got to enjoy this! me getting burnt"

Or not, as it turned out.

I'm sorry to hear about the cancer. My dad died of cancer when I was about 9 or 10, after having problems with it all of the time I was growing up. Which is partly to blame for me 'self harming' (experimenting on myself) in this manner, no one bothered to stop me doing this as I grew up; so I'd already been connected to the mains a few times before I was allowed a pen at school.

I do have major concerns over toxic and really horrible things, and especially the innocuous carbon monoxides of the world. But I also don't like it when people group things under the same blanket response, as it encourages people to treat them all as equal, when they're not. Or worse, do the reverse. Huffing hydrogen chloride, a tiny sniff of it induces an eye watering coughing fit. Then it's gone. Carbon monoxide goes through fume hoods and is entirely undetectable to our senses. It's systemically toxic (both to metabolism and the nervous system) and lethal. Yet which is it that people are most scared of? The wrong one.

I'm fine putting some drops of piranha on my handies. I would have a mask, gloves, face shield, apron and whatnot on for HF.

With that diversion aside, back to making salt... soon as the posty arrives, again.

[Edited on 1-9-2010 by peach]

blogfast25 - 2-9-2010 at 12:01

John, can't believe you put that stuff on your hands voluntarily. Did you have prior art stating that it would be OK?

peach - 2-9-2010 at 12:54

The prior art is simply from countless hours stood at the sink washing things with these kinds of chemicals and concentrations. Some organic gunk will outright refuse to budge with anything less.

It is nasty but, as I say in the video, it can sit there for minutes. It's at the point that I wipe it off that the damage would massively accelerate.

A lot of thermal and chemical burns are like this. The horribly scared people you see who've had acid thrown in their faces are like that because they couldn't get it back off within a few minutes (when it starts digging it), and don't know what it is, how to deal with it and likely have it in their eyes as well. As with numerous other hazards, it's a major one when you don't know it's there.

Shortly after making that video, I slipped on the grass outside and kicked the door frame hard enough to have my big toe bleeding; it's now purple. That could have been my back on the frame or head on the concrete floor (Dr Atkins died this way). Because I didn't know it was so slippery.

I wouldn't recommend it, obviously (and didn't mention it in the videos since a lot of teenagers and younger watch youtube), but I still mouth pipette things like concentrated sulphuric, and even piranha.

[Edited on 2-9-2010 by peach]

MolecularConcept - 10-9-2010 at 19:18

Yo peach itssss MEEE, MC! Finally got SM to sign me in.

On page 1what are those attachments on top of the addition funnel and on top of the 3 neck? (Haha using RBFs now I see haha)

If one where to actually have some AlCl3 and added it (how much?) to serve as a catalyst. Would this work as it said to?

peach - 10-9-2010 at 19:20

Quote: Originally posted by MolecularConcept

On page 1what are those attachments on top of the addition funnel and on top of the 3 neck? (Haha using RBFs now I see haha)

I was hoping no one would notice that...

Yep, I'm on the RBF's now after the last conical broke (none of them ever broke under vacuum). Although, I doubt the new 1l RBF I have is going to fair better, because the guy I bought it from has scratched the buggery out of it and then sold it as fine.

The things I think you're thinking of are gas wash heads.

Not sure about how much would be needed to start the reaction, Vogel might mention it.

[Edited on 11-9-2010 by peach]

AJKOER - 19-6-2011 at 10:12

If one has an aqueous solution of AlCl3 and one adds Ethanol (which dissolves both AlCl3 and water), and let the solution evaporate without heating, do you successful obtain anhydrous AlCl3?

Thanks

blogfast25 - 19-6-2011 at 13:23

Quote: Originally posted by AJKOER

If one has an aqueous solution of AlCl3 and one adds Ethanol (which dissolves both AlCl3 and water), and let the solution evaporate without heating, do you successful obtain anhydrous AlCl3?

Thanks

No, would be my guess. The hydrate AlCl3.6H2O is sufficiently stable without the crystal water evaporating off in these conditions. To get from the hydrate to the anhydrous form you'd probably have to heat the former in a stream of pure, dry HCl gas.

Or synthesise the chloride in water free conditions.

[Edited on 19-6-2011 by blogfast25]

Vogelzang - 19-6-2011 at 14:57

Here's something I had saved.

http://www.mediafire.com/?fhb2hz7j58faxq6

http://www.mediafire.com/?ag20w01rr4szz9c

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