Sciencemadness Discussion Board - The Short Questions Thread (4)

The Short Questions Thread (4)

Pages: 1 2 3 4 .. 26

bbartlog - 10-11-2013 at 12:15

Seems like you'd first need to hydrolyze it to monomers, and then convert it to dioxane via some means such as heating with sulfuric acid. Those individual steps should be easy enough to research, I know that the latter at least has been discussed on this forum.

Question

confused - 17-11-2013 at 15:54

would calcium hydroxide work for a base catalysed hydrolysis of acetylsalicyclic acid to salicyclic acid?
is there any way to know when the reaction has come to completion?

UnintentionalChaos - 17-11-2013 at 16:16

Quote: Originally posted by confused

would calcium hydroxide work for a base catalysed hydrolysis of acetylsalicyclic acid to salicyclic acid?
is there any way to know when the reaction has come to completion?

Boiling water is enough to get the decomposition going, so I'm going to say "yes."

Lambda-Eyde - 17-11-2013 at 16:20

If I'm going to guess, calcium salicylate won't be very soluble. Boiling water works, but adding a few drops HCl speeds it up and makes the workup easier.

I Like Dots - 19-11-2013 at 17:24

Where can I find general a procedure on forming ketone and aldehyde sodium bisulfite adducts?
http://www.erowid.org/archive/rhodium/chemistry/eleusis/bisu... This is the closest I have gotten.

I plan on separating the benzaldehyde from almond extract. Im going to try with acetone also.

SHADYCHASE54 - 27-11-2013 at 08:06

I have a quick question regarding removing the acetyl group from n-acetyl-4-piperidone what I am wondering is were I to reflux with a slight molar excess of potassium hydroxide will I shed the acetyl leaving the 4-piperidone in tact? If you have any experience I would love to hear from you as well if you might have any pertinent refs all aid would be appreciated.

plante1999 - 28-11-2013 at 14:29

Does anyone know where I can find a good preparation for:

Diethyl azodicarboxylate

Thanks!

plante1999 - 28-11-2013 at 15:32

Quote: Originally posted by plante1999

Does anyone know where I can find a good preparation for:

Diethyl azodicarboxylate

Thanks!

You can see it here, thanks me latter:

http://www.orgsyn.org/Content/pdfs/procedures/CV4P0411.pdf

Pyro - 29-11-2013 at 11:19

I distilled technical quality toluene, to keep it completely anhydrous I added a few thin flakes of pure Na.
two days later they look like this:

what could there be in redistilled toluene that turns brown in contact with Na or NaOH?

Do I need to distill it again, or can I get away with filtration? (400ml)

elementcollector1 - 29-11-2013 at 12:36

Seems like sodium oxide - I get that brown/yellow finish on my sodium as well. Not in toluene, though.

Pyro - 30-11-2013 at 12:02

Ok, thanks. Do I need to re-distill it or can I just filter the floating ''stuff'' out?

elementcollector1 - 30-11-2013 at 13:18

Quote: Originally posted by Pyro

Ok, thanks. Do I need to re-distill it or can I just filter the floating ''stuff'' out?

Should probably re-distill it, but either way works. The 'stuff' should also keep your solution dry, so best to keep it in there long-term.

Pyro - 30-11-2013 at 13:20

the Na sinks in toluene, but the stuff looks like scurf and floats around

bismuthate - 30-11-2013 at 15:50

How would FeCl3 react with sodium acetate?

DraconicAcid - 30-11-2013 at 18:00

Quote: Originally posted by bismuthate

How would FeCl3 react with sodium acetate?

Probably through hydrolysis. Fe³⁺ + H₂O + OAc^- -> Fe(OH)²⁺ + HOAc.

With enough acetate ion, you'll get iron(III) hydroxide precipitating.

BlackDragon2712 - 1-12-2013 at 17:14

Question

does anyone knows where to get tert-butanol?

[Edited on 06/11/2013 by BlackDragon2712]

plante1999 - 1-12-2013 at 17:31

I do.

elementcollector1 - 1-12-2013 at 17:33

Quote: Originally posted by BlackDragon2712

Question

does anyone knows where to get tert-butanol?

[Edited on 06/11/2013 by BlackDragon2712]

U2U sent regarding potential availability. Unfortunately, I have no idea where you live...

chemrox - 1-12-2013 at 20:40

Quote: Originally posted by I Like Dots

Where can I find general a procedure on forming ketone and aldehyde sodium bisulfite adducts?
http://www.erowid.org/archive/rhodium/chemistry/eleusis/bisu... This is the closest I have gotten.

I plan on separating the benzaldehyde from almond extract. Im going to try with acetone also.

Check the library here. This is covered in "purification of laboratory chemicals."

I would do a fractional distillation first. You could skip the bisulfite step as most oil of bitter almond is 98% (or more) benzaldehyde.

chemrox - 1-12-2013 at 20:53

Quote: Originally posted by SHADYCHASE54

I have a quick question regarding removing the acetyl group from n-acetyl-4-piperidone what I am wondering is were I to reflux with a slight molar excess of potassium hydroxide will I shed the acetyl leaving the 4-piperidone in tact? If you have any experience I would love to hear from you as well if you might have any pertinent refs all aid would be appreciated.

Try strong base in ethylene glycol or DMSO. 4-piperidone polymerizes on formation so it is sold as the dihydro-HCl. The water molecules are a formality since it is actually a diketal. Let me know how it goes or send me what you've got and I'll give you an eq amt of the product of commerce.

bismuthate - 5-12-2013 at 15:19

Does anybody know a solvent for calcium/alkali metal carbides?

DraconicAcid - 5-12-2013 at 15:25

Calcium carbide is actually an acetylide- a strong base, but one can work with it. Avoid esters and alcohols, obviously, but you need something polar or it won't dissolve. Acetonitrile is probably to acidic; acetone is too vulnerable to nucleophilic attack...I'd try THF. Even if it's not very soluble, it might disperse enough to be a good reaction medium.

For an alkali metal acetylide, you might be able to make it more soluble by adding TMEDA (tetramethylethylenediamine).

[Edited on 5-12-2013 by DraconicAcid]

bismuthate - 5-12-2013 at 15:39

(I don't know much about organic chem so I may say something stupid)From what I have seen on SM CaC2 does not seem to react with ethanol. Might it be slightly soluble in that? I would also wonder about liquid ammonia.

[Edited on 5-12-2013 by bismuthate]

elementcollector1 - 7-12-2013 at 23:03

Online sources typically state the concentration of selenium in dietary supplements to be 200 micrograms per tablet. Considering each tablet weighs considerably more than 200 ug, what's the rest?

confused - 8-12-2013 at 00:00

my guess would be binders,preservatives and flavors or sweeteners
http://en.wikipedia.org/wiki/Excipient

plante1999 - 8-12-2013 at 19:53

Does anyone have a book that details the classic chemistry experiments/demonstration such as coal distillation, lead chamber demo, etc?

I have look for a book about theses early 1900 experiments for a while now.

Thanks

DraconicAcid - 8-12-2013 at 20:14

I have a book that does destructive distillation of coal and wood, IIRC, but it doesn't have anything about the lead chamber process.

elementcollector1 - 8-12-2013 at 20:41

Quote: Originally posted by confused

my guess would be binders,preservatives and flavors or sweeteners
http://en.wikipedia.org/wiki/Excipient

Seems like most of them are organic sugars and such. Thanks!

plante1999 - 9-12-2013 at 04:03

Quote: Originally posted by DraconicAcid

I have a book that does destructive distillation of coal and wood, IIRC, but it doesn't have anything about the lead chamber process.

It was just to give an idea of the type of book I was talking, it is not obligated to have the three.

Thanks

DraconicAcid - 9-12-2013 at 09:43

I have "New Laboratory Experiments in Practical Chemistry" by Newton, Henry, and Black (1949), which has the destructive distillation of coal (but not of wood).
I also have "Elements of Chemistry" by Shepard (1885), which includes an experiment where the student makes a solution of prussic acid, and feeds a teaspoon of it to a cat.

plante1999 - 9-12-2013 at 09:54

"(...)which includes an experiment where the student makes a solution of prussic acid, and feeds a teaspoon of it to a cat"

Look exactly like what I want.

Thanks!

Question

confused - 10-12-2013 at 07:51

Hi, i was wondering if this platinum electrode could be used for the eletrolysis of copper sulfate solution into sulfuric acid

2 Cu2SO4 + 2 H2O = 4 Cu + 2 H2SO4 + O2

http://www.aliexpress.com/item/1-0-micron-50x50mm-Platinum-C...

would the platinum coating be too thin? 1 micron seems really thin for an electrode.

Also, how thin can the coating be before it is no longer practically usable for this application?

would a 0.5 micron thick coating work, as the prices for the diffrent thicknesses of coating differ somewhat substantialy

0.5 micron, 1.0 micron and 2.5 micron
Price is USD 18, USD 33 and USD 83

Metacelsus - 10-12-2013 at 19:42

I hope this question qualifies as "short":

I am studying the kinetics of a certain reaction in which a two starting materials react to form an isolable intermediate, which then reacts with another equivalent of one of the original starting materials to form the final product. Both of the reactions are second order. In my case the first reaction happens significantly faster than the second one, but not so fast that it can be assumed to always be at equilibrium.

1) A + B -> C
2) A + C -> D

I have written these differential equations to describe the system:

d[A]/dt=-k₁[A][B]-k₂[A][C]
d[B]/dt=-k₁[A][B]
d[C]/dt=k₁[A][B]-k₂[A][C]
d[D]/dt=k₂[A][C]

I assumed this type of reaction was a common one, but have not been able to find the general solution, or even a simplified form, of this type of system. (Experimentally, both [A] and [B] decrease with time, [C] increases and then decreases, and [D] increases.) Does anyone here have experience and/or knowledge with this type of reaction?

If it matters, I can tell you what compounds A, B, C, and D are.

DubaiAmateurRocketry - 11-12-2013 at 00:04

I wanted to repeat a nitration process a paper stated, they used HCl/HNO3/Ac2O, however I have only pure HNO3 and P2O5.

I also dont have sulfuric acid. Can I do HNO3/ P2O5 ?

confused - 11-12-2013 at 02:30

what exectly do you want to nitrate?
also, do you have the paper u mentioned?

Galinstan - 11-12-2013 at 05:51

No, HNO3 and P2O5 in ether will not nitrate anything as it won't create the nitronium ion ( the nitrating specie in most cases)

DubaiAmateurRocketry - 11-12-2013 at 06:10

Thanks for both of you answering,

I have > 95% HNO3 and so adding more P2O5 to take water out, will generate Nitronium Nitrate, NO2 NO3, a good nitration performer,

The nitration I wanted to perform on is a triazole compound, I fear the P2O5/HNO3 will be too powerful and the N2O5 generated might cause ring opening and destroy my experiment, something N2O5 can do.

I've only half a liter of HNO3 left and I dont want to waste one gram of it

Galinstan - 11-12-2013 at 07:28

Ah i stand corrected i din't realise P4O10 had the power to dehydtate HNO3.

DubaiAmateurRocketry - 21-12-2013 at 17:21

whats the most common material that can stand cold temperature, sulfuric acid, and nitric acid at same time?

elementcollector1 - 21-12-2013 at 17:23

Quote: Originally posted by DubaiAmateurRocketry

whats the most common material that can stand cold temperature, sulfuric acid, and nitric acid at same time?

Glass.

Zyklon-A - 21-12-2013 at 17:29

Very true.

DubaiAmateurRocketry - 21-12-2013 at 17:59

Quote: Originally posted by elementcollector1

Quote: Originally posted by DubaiAmateurRocketry

whats the most common material that can stand cold temperature, sulfuric acid, and nitric acid at same time?

Glass.

anything other than glass ?

bismuthate - 21-12-2013 at 19:10

I'm not sure, but how about porcelain? Or do you have anything Si plated?

Zyklon-A - 21-12-2013 at 19:13

Gold.

bismuthate - 21-12-2013 at 19:15

He (or she) said common. Also would that etch gold like aqua regia?
Maybe PTFE.

[Edited on 22-12-2013 by bismuthate]

[Edited on 22-12-2013 by bismuthate]

plante1999 - 21-12-2013 at 19:57

Quote: Originally posted by DubaiAmateurRocketry

whats the most common material that can stand cold temperature, sulfuric acid, and nitric acid at same time?

iron

elementcollector1 - 21-12-2013 at 20:02

Uh, no? Iron wouldn't hold up to that. At least not the sulfuric acid.

plante1999 - 21-12-2013 at 20:27

I bet anything you want, iron WILL hold that.

Seriously, industrial nitrator are made of iron...

It passivate.

DubaiAmateurRocketry - 22-12-2013 at 03:10

Quote: Originally posted by bismuthate

Maybe PTFE.

Yup, i was thinking on the same line.

Quote: Originally posted by plante1999

I bet anything you want, iron WILL hold that.

Seriously, industrial nitrator are made of iron...

It passivate.

Alright ahha, ill try that in small ammounts and tell u the results

Mailinmypocket - 22-12-2013 at 12:16

I just aquired a bottle of "animal bone charcoal", can this be used as decolorising charcoal? Not sure what it's purpose is otherwise besides being incredibly messy

[Edited on 22-12-2013 by Mailinmypocket]

DubaiAmateurRocketry - 23-12-2013 at 04:09

Is there other way to get 70% nitric acid up to >90% without distillation ? I have strong dessicants such as Ac2O, P2O5, magnesium perchlorate/ sulfate.

I am not sure how to get the acetic acid or phosphoric acid out of my 95% HNO3 after the water is gone though.

bismuthate - 23-12-2013 at 04:20

On the wiki page for N2O5 it shows that nitric acid is dehydrated by P2O5 (even to the point of becoming N2O5) but if you used it how would you get rid of the H3PO4?

kristofvagyok - 23-12-2013 at 05:17

Quote: Originally posted by bismuthate

On the wiki page for N2O5 it shows that nitric acid is dehydrated by P2O5 (even to the point of becoming N2O5) but if you used it how would you get rid of the H3PO4?

N2O5 could be easily distilled/sublimed out from the reaction mixture, since it has a really low boiling point.

DJF90 - 23-12-2013 at 09:15

Theres a preparation in Brauer that does exactly that.

plante1999 - 23-12-2013 at 13:36

Very short question, does anyone know if you can order from McMaster-carr as an individual?

If so, how do we proceed?

Thanks

DubaiAmateurRocketry - 23-12-2013 at 15:42

Quote: Originally posted by kristofvagyok

Quote: Originally posted by bismuthate

On the wiki page for N2O5 it shows that nitric acid is dehydrated by P2O5 (even to the point of becoming N2O5) but if you used it how would you get rid of the H3PO4?

N2O5 could be easily distilled/sublimed out from the reaction mixture, since it has a really low boiling point.

Hehe its dissolved, and you cant distill it, it will simply decompose into N2, O2 and NOx.

I would really want an answer on how to get phosphoric acid out of HNO3, after I dried the water, or obtained some N2O5 in dissolved HNO3

bismuthate - 23-12-2013 at 18:22

We'll you could only add enough P2O5 to dehydrate it to 90% and distill.
You could try vacuum sublimation or dissolving it in Chloroform.

[Edited on 24-12-2013 by bismuthate]

[Edited on 24-12-2013 by bismuthate]

Zyklon-A - 26-12-2013 at 09:36

I'm buying some test tubes from elementalscientific.net, and it only sells rubber stoppers separately, the tubes are 20 mm across, but their stoppers use a different scale (or whatever you call it), does anybody know what size stopper fits a 20 mm test tube?

Mailinmypocket - 26-12-2013 at 09:45

Just checked for you, you would want to get a number 2... 1 fits but is a bit too small

Zyklon-A - 26-12-2013 at 09:58

Thank you.

S.C. Wack - 26-12-2013 at 11:07

Quote: Originally posted by Zyklonb

I'm buying some test tubes from elementalscientific.net, and it only sells rubber stoppers separately, the tubes are 20 mm across, but their stoppers use a different scale (or whatever you call it), does anybody know what size stopper fits a 20 mm test tube?

http://www.tekniscience.com/documents/Corning_Guide_for_Sele...

DubaiAmateurRocketry - 26-12-2013 at 14:15

Is it possible to concentrate H2O2 solution using dessicants ? Such as Magnesium sulfate/ lithium perchlorate ?

chemrox - 26-12-2013 at 17:14

Does the use of NaCNBH3 add methyl to the reductant? I should know and can't find the ref on reductions with metal hydrides. Thanks.

Zyklon-A - 26-12-2013 at 19:48

Quote: Originally posted by DubaiAmateurRocketry

Is it possible to concentrate H2O2 solution using dessicants ? Such as Magnesium sulfate/ lithium perchlorate ?

Why not just evaporate it off with heat?

Brain&Force - 26-12-2013 at 21:09

Quote: Originally posted by Zyklonb

Quote: Originally posted by DubaiAmateurRocketry

Is it possible to concentrate H2O2 solution using dessicants ? Such as Magnesium sulfate/ lithium perchlorate ?

Why not just evaporate it off with heat?

Or you could react barium peroxide with nitric acid (if you have them). Just make sure there are no transition metal impurities or else it will decompose on production.
Basic hydrogen peroxide can be made by adding sodium peroxide to water (and sodium peroxide can be made by burning sodium in air). It will be strongly basic however.

Zyklon-A - 26-12-2013 at 21:38

Sodium is very costly, as are Barium peroxide and nitric acid, also it's not very pure, not worth it at all.

elementcollector1 - 27-12-2013 at 08:33

Since I can't seem to find any sort of help on this: How do you set up a water aspirator? More specifically, I'm confused about the top - it looks as though it should thread onto a hose or sink or some such.

Mailinmypocket - 27-12-2013 at 08:51

Ugh I had a hell of a time when I bought mine... I bought the brass attachment bit from the same company that I got the aspirator from. I think this is the part you are referring to, it seems to be hard hose size. They sold it as a faucet adapter but it clearly is not for household tape anyways. I went to a aquarium specialty store and bought the white piece, it's a tap adapter for a "Python" aquarium vacuum thing, it converts the kitchen tap thread size into the required size. It cost me something like $4. I would have liked a metal one but oh well... It works perfect anyways.

**edit: here is the item http: http://www.amazon.com/gp/product/B000255NUU?ie=UTF8&forc... it actually consists of two pieces, the top bit is a male end which you may or may not need depending on your faucet

[Edited on 27-12-2013 by Mailinmypocket]

[Edited on 27-12-2013 by Mailinmypocket]

DubaiAmateurRocketry - 27-12-2013 at 14:30

can any of those cation and anion go together to form a salt, or any of the below already exist ?

Amino-tetrazolium, dioxygenyl, nitronium, ammonium, hydrazine, guanidine.

peroxide /superoxide /ozonide/hydride/aluminum hydride/borohydride.

DraconicAcid - 27-12-2013 at 14:43

Quote: Originally posted by DubaiAmateurRocketry

can any of those cation and anion go together to form a salt, or any of the below already exist ?

Amino-tetrazolium, dioxygenyl, nitronium, ammonium, hydrazine, guanidine.

peroxide /superoxide /ozonide/hydride/aluminum hydride/borohydride.

I doubt it. Ions like aminotetrazolium, ammonium and hydrazinium are acidic; anions like peroxide, superoxide, and hydride are strong bases, and would immediately react. Cations like dioxygenyl, nitronium and nitrosyl are strongly electrophilic (Lewis acids) and would similarly react immediately with the anions you've listed.

DubaiAmateurRocketry - 27-12-2013 at 17:31

thank you draconic acid, i know acid/ base salts rarely or dont come together however hydroxyl ammonium perchlorate, for example, exist. Yes the ones i pointed out is more extreme but just sayin.

http://www.tandfonline.com/doi/abs/10.1080/07370650008216114...

Also I wonder if this paper is true, It says Ammonium superoxide/ ozonide is a solid ? really ?

Quote: Originally posted by bismuthate

On the wiki page for N2O5 it shows that nitric acid is dehydrated by P2O5 (even to the point of becoming N2O5) but if you used it how would you get rid of the H3PO4?

I wonder.. Maybe distill ? I personally hate distillating though, any other way ?

______

And another question.

How reactive is Aluminum hydride ?

I was reading a paper on a crazy rocket fuel that uses aluminum hydride as a fuel mixed in some nitrate ester plasticizers and seems they have no problem with it. However nitronium perchlorate is obviously coated.

US Patent - Plasticized nitrocellulose propellant containing Aluminum hydride and Nitronium perchlorate.
https://docs.google.com/viewer?url=patentimages.storage.goog...

[Edited on 28-12-2013 by DubaiAmateurRocketry]

[Edited on 28-12-2013 by DubaiAmateurRocketry]

elementcollector1 - 29-12-2013 at 16:32

Quote: Originally posted by Mailinmypocket

Ugh I had a hell of a time when I bought mine... I bought the brass attachment bit from the same company that I got the aspirator from. I think this is the part you are referring to, it seems to be hard hose size. They sold it as a faucet adapter but it clearly is not for household tape anyways. I went to a aquarium specialty store and bought the white piece, it's a tap adapter for a "Python" aquarium vacuum thing, it converts the kitchen tap thread size into the required size. It cost me something like $4. I would have liked a metal one but oh well... It works perfect anyways.

Got a plastic adapter for mine. Judging from a cursory test with the garden hose, it pulls pretty strong vacuum. Getting a vacuum gauge within a week or so (although questionable about the authenticity, it's $5... http://www.amazon.com/gp/product/B004VU8Q5Q/ref=oh_details_o...)

LiD - 29-12-2013 at 18:14

What would happen to U-235 if we would irradiate it with a weak, less than 1MeV H+ beam? Would Np-236 form?

Question

elementcollector1 - 29-12-2013 at 23:37

What is the most convenient way to prepare sodium hexametaphosphate ((NaPO₃)₆) from sodium orthophosphate (Na₃PO₄)? Wikipedia states conversion to the dihydrogen salt (with concentrated H₂SO₄?) followed by melting and rapid cooling (how would one rapidly cool? Dunk container in cold water?)

HeYBrO - 31-12-2013 at 02:33

Quote:

101. Preparation of Ethyl Acetate from Alcohol and Acetic Acid.—(SECTION 160).—Mix in a dry 200 cc. distilling flask 50 grams of alcohol, 60 grams of glacial acetic acid, and 4 cc.
concentrated sulphuric acid. from norris experimental o-chem

I'm bit unclear on how much % excess alcohol must be used in esterificationss. This procedure uses 1.085 mol EtOH and 1 mol AcOH. Is that really enough? Also, bit of a noob question how would you calculate the % excess?

Question about paraformaldehyde and imines

Metacelsus - 31-12-2013 at 16:53

Can paraformaldehyde be used to form imines?
Specifically, I'm thinking about the reaction with ethylamine to form N-methylethanimine.
If not, is there another form of formaldehyde I could use?

acid salts quick question

Random - 1-1-2014 at 11:00

Does monosodium citrate react with trisodium citrate to form two amounts of disodium citrate?

bfesser - 1-1-2014 at 11:03

Yes. Equilibrium. Next time, post in the right place. Spamming Beginnings out of laziness is unacceptable, and I may move such posts to Detritus.

[Edited on 1.1.14 by bfesser]

Nicodem - 1-1-2014 at 11:24

Quote: Originally posted by Cheddite Cheese

Can paraformaldehyde be used to form imines?
Specifically, I'm thinking about the reaction with ethylamine to form N-methylethanimine.
If not, is there another form of formaldehyde I could use?

The condensation of ethylamine with (para)formaldehyde does not give N-methylethanimine. You need acetaldehyde and methylamine for that.
The condensation of primary amines with formaldehyde normally gives the corresponding 1,3,5-trialkyl-hexahydro-s-triazines. The reaction with paraformaldehyde gives the same product, just much more slowly.

DubaiAmateurRocketry - 2-1-2014 at 19:23

Does hydrated sodium sulfate dissolve in Ethanol or methanol ?

elementcollector1 - 2-1-2014 at 19:55

Not sure whether to post this in Bad days in the lab or with glassware? or here... so I'll post it here.
I recently received a vacuum gauge. However, it is currently at 4.5 inches Hg despite not being connected to anything. How do I fix this?

[Edited on 1-3-2014 by elementcollector1]

DubaiAmateurRocketry - 7-1-2014 at 07:30

Whats the easiest way to measure the visousity of a liquid ? the answer does not havet to be perfect.

Zyklon-A - 7-1-2014 at 07:56

http://www.wikihow.com/Measure-Viscosity
(I have not tried this method myself yet.)

[Edited on 7-1-2014 by Zyklonb]

DubaiAmateurRocketry - 7-1-2014 at 08:07

Is there a method I heard that you put a drop on a flat board like object, and then place this thing at an angle, and it will flow down, the time it takes to cover what ever distance is its visousity. I dont know what is that called..

bfesser - 7-1-2014 at 08:16

No, DubaiAmateurRocketry, that is not a valid way of measuring viscosity—it would be more of a measure of <a href="https://en.wikipedia.org/wiki/Adhesion" target="_blank">adhesion</a> <img src="../scipics/_wiki.png" /> than <a href="https://en.wikipedia.org/wiki/Viscosity" target="_blank">viscosity</a> <img src="../scipics/_wiki.png" />. <a href="https://en.wikipedia.org/wiki/Viscometer" target="_blank">Viscometers</a> <img src="../scipics/_wiki.png" /> and stopwatches are readily and cheaply available on eBay. Also, please don't use this thread as a substitute for a simple <a href="http://lmgtfy.com/?q=measure+viscosity" target="_blank">Google</a> <img src="../scipics/_ext.png" /> or literature search.

[Edited on 7.1.14 by bfesser]

alexleyenda - 7-1-2014 at 10:26

When something is soluble in Ethanol, can I assume it will also be soluble in methanol? Same question for insoluble?

DraconicAcid - 7-1-2014 at 10:50

Quote: Originally posted by alexleyenda

When something is soluble in Ethanol, can I assume it will also be soluble in methanol? Same question for insoluble?

The solubility of a solute in methanol will differ quantitatively from that in ethanol, but not by much (for most solutes).

Zyklon-A - 7-1-2014 at 17:20

I have a question, I guess.
I was producing H2 this morning, via reaction of Al with HCl(aq), in a test tube, (for another reaction), however something strange happened, I put a cork (an actual cork not a rubber stopper) on the tube, and then the H2 caught on fire, not a big deal of course, but it was random. I want to know why it caught fire, that has never happened to my before.
The tube was warm (from the reaction), but not hot, the cork caught on fire too, thus keeping the flame alive.

I blowed it out but it caught fire again, and again, I think 4-5 times.
Does anyone know why it did that? Perhaps the cork acts as a catalyst of some kind, I know Pt catalyzes the reaction of H2 and O2, maybe this does as well?

For the record, I tried it again but it failed to work.

elementcollector1 - 7-1-2014 at 17:23

H₂ usually burns with an invisible flame - are you sure something else wasn't catching fire somehow?

Zyklon-A - 7-1-2014 at 18:13

Like I said, the cork did catch on fire, but it was the H₂ that initiated the reaction.

[Edited on 8-1-2014 by Zyklonb]

Mailinmypocket - 7-1-2014 at 18:51

Did the cork pop out of the tube when this event took place? When you were blowing it out and it was continuously reigniting, was this due to the burning cork still being on the tube? Hydrogen usually burns with a pop and doesn't reignite itself if generated in a test tube and lit while being generated.

Let's just say the cork was a catalyst in some parallel universe, it should be able to cause the same thing to happen again if repeated. The fact that it did not makes me wonder what else was around or going on, it's very hard to imagine how this would happen by reading your post!

alexleyenda - 7-1-2014 at 19:00

To me it sounds like your cork stopper was contaminated by some kind of catalyst. Also it could help to describe a bit more how it happened. Was the stopper made with an hole and connected to tubing or was it a solid stopper. Did you put it during the reaction or after just to contain the hydrogen? By the way H2's flame is very easy to see if something else burns around it ( like cork for example ) ! It also often comes with a noise when it ignites and the heat and the distortion of the air it causes is also easy to detect.

[Edited on 8-1-2014 by alexleyenda]

Metacelsus - 7-1-2014 at 19:20

My guess: static electricity. Can you provide more detail on how the hydrogen reignited? Did the cork serve as a sort of pilot light?

Zyklon-A - 7-1-2014 at 19:51

Quote: Originally posted by Mailinmypocket

Did the cork pop out of the tube when this event took place? When you were blowing it out and it was continuously reigniting, was this due to the burning cork still being on the tube? Hydrogen usually burns with a pop and doesn't reignite itself if generated in a test tube and lit while being generated.

Let's just say the cork was a catalyst in some parallel universe, it should be able to cause the same thing to happen again if repeated. The fact that it did not makes me wonder what else was around or going on, it's very hard to imagine how this would happen by reading your post!

Yes the cork did pop out, the first time it hit the roof, the other times there was not enough H₂ to hit the roof, but it did pop up.

Zyklon-A - 7-1-2014 at 19:53

Quote: Originally posted by Cheddite Cheese

My guess: static electricity. Can you provide more detail on how the hydrogen reignited? Did the cork serve as a sort of pilot light?

Yes, that's exactly my guess, but as for the first time....

Zyklon-A - 7-1-2014 at 19:58

The cork was solid, also there was pressure building up in the tube, I'm starting to doubt that a catalyst is the cause, I think it may be static electricity, as Cheddite Cheese stated. I'm not sure though.

Edit: Ok, I tried it again, and it happened again!
Can someone else try it too, maybe my cork is special?
This is so weird, LOL.

[Edited on 8-1-2014 by Zyklonb]

alexleyenda - 7-1-2014 at 20:51

I don't know why you would put a solid stopper on an ongoing gas producing reaction :p but anyways my guess would be that with the pressure, a bit of H2 escapes really quickly around the stopper and the friction creates enough heat to ignite the H2. Another theory, this one is quite mad but who knows: There is H2 and O2 in the flask, pressure builds up, the 2 H2 + O2 ---> 2 H2O reaction is favorised as 2 moles of gas takes less place than 3 moles of gas so even if the flask is only warm it ignites to counterbalance the pressure.

[Edited on 8-1-2014 by alexleyenda]

elementcollector1 - 7-1-2014 at 21:07

^Not likely. At STP, a mole of gas is 22.4 liters. The average test tube is about 10-20 mL, so you do the math. There is much more hydrogen than oxygen, and as far as I know only the stoichiometric mixture is prone to spontaneous explosion.

alexleyenda - 7-1-2014 at 22:25

Yeah I was just talking about the mole ratio and I know that in normal conditions it would not happen but as it is under pressure, maybe .. ! Anyways as I said this is a mad theory, I don't really think it is right but hey I would give it a try, you could maybe try it with a rubber stopper to see if it works. If it doesnt then there are good chances it is because of the pressure.

[Edited on 8-1-2014 by alexleyenda]

Zyklon-A - 8-1-2014 at 06:15

I think a nonstoichiometric mixture could at least ignite, (From Wikipedia: ''Hydrogen is easily ignited, as it is flammable over a wide range of concentrations in air, so that the test does not rely on having an exact mixing ratio.'') Obviously there is some 02 in there. I don't think that the pressure in the tube could ignite it though, it happening twice at different times rules out static electricity, I think.
Edit: tried a rubber stopper, nothing happened.

[Edited on 8-1-2014 by Zyklonb]

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