Sciencemadness Discussion Board
Not logged in [Login ]
Go To Bottom

Printable Version  
 Pages:  1    3    5  ..  30
Author: Subject: The short questions thread (2)
Jor
International Hazard
*****




Posts: 950
Registered: 21-11-2007
Member Is Offline

Mood: No Mood

[*] posted on 30-4-2009 at 15:38


I have some 'barium carbonate', but i highly doubt it is this compound right now.
I added a spatula to 3M HNO3 and even after heating to boiling, none seems to dissolve at all.

So this means that it is not barium carbonate right?

Maybe my supplier confused and gave me the sulfate.

oh, and I am now an 'International Hazard' :cool:

[Edited on 30-4-2009 by Jor]
View user's profile View All Posts By User
Globey
Hazard to Others
***




Posts: 183
Registered: 9-2-2009
Member Is Offline

Mood: No Mood

[*] posted on 30-4-2009 at 17:16


OK, so it's not a chem question...more physics. Let's say one took one's nice digital HDV camcorder, and set an ungodly frame rate like 1,000,000 FPS or higher (consumer models easily do 10K FPS). One's camera is in the sky very high up, looking down on an area of land let's say several hundred miles in length and maybe 150miles in width (not really important). Anyway, recording is commenced, and a powerful, visible laser (nicely expanded/culminated) and focused, is shone 90 Deg perpendicular, on a 2D plane to the camera. With a slowed down play back, would one be able to literally witness the beam of light as it travels in space? Where you could actually watch the leading edge of the laser light (like a slug of light) as it progresses in space? How cool would that be.
View user's profile View All Posts By User
Paddywhacker
National Hazard
****




Posts: 478
Registered: 28-2-2009
Member Is Offline

Mood: No Mood

[*] posted on 30-4-2009 at 23:22


The effect can be seen in astronomy, where a the light front from a nova, for example, lights up a dust cloud that lies in space at an angle to the light wavefront. Observers here see an illuminated patch of cloud that appears to be moving faster than light, but it is only different parts of the light wavefront impacting the extended dust cloud.
View user's profile View All Posts By User
appetsbud
Harmless
*




Posts: 21
Registered: 15-8-2008
Member Is Offline

Mood: No Mood

[*] posted on 1-5-2009 at 11:12


I read: "Also, low concentrations (4 ppm) will anesthetize the nose, thus creating a potential for overexposure." on wiki, does this mean one will not be able to smell anything? or just the chemical in question? (NO2)
View user's profile View All Posts By User
S.C. Wack
bibliomaster
*****




Posts: 2419
Registered: 7-5-2004
Location: Cornworld, Central USA
Member Is Offline

Mood: Enhanced

[*] posted on 2-5-2009 at 20:39


Quote: Originally posted by Jor  

Maybe my supplier confused and gave me the sulfate.


I got sulfide in mine. Lots of H2S being carried by CO2 on acidification is not a good thing when you are expecting just CO2. The sulfate can be converted to the carbonate by boiling in baking soda solution for some hours.

Does anyone know where to get some Buchi condenser vacuum/water threaded connectors (GL-14) for cheap? Bought an older coil condenser, vapor duct, and receiver for $4 today. But the condenser didn't have the connectors and this bothers me. It would be a shame to rig something ugly to it.

What bothers me more is that I stopped bidding just last weekend at $40 (the winning bid) for one of the older Rotavap models, because it was older and worn, I already have a perfect + complete R110, and because it was missing the condenser and receiver.
View user's profile Visit user's homepage View All Posts By User
kclo4
International Hazard
*****




Posts: 915
Registered: 11-12-2004
Location:
Member Is Offline

Mood: No Mood

[*] posted on 2-5-2009 at 22:11


Chloroplasts can reduce the blue DCPIP to a colorless compound. What is the reduction potential, or what else could chloroplasts reduce? I don't know why, but I am intrigued by the idea of stealing protons from chloroplasts. :D



View user's profile Visit user's homepage View All Posts By User
Aubrey
Harmless
*




Posts: 37
Registered: 16-11-2008
Member Is Offline

Mood: No Mood

[*] posted on 4-5-2009 at 08:17


I wish to dehydrate some Benzamide to Benzonitrile using Phosphorus Pentoxide. Does anyone have a reference to this reaction or know how I may go about it? Should i just heat the two until they form a melt for several hours?
View user's profile View All Posts By User
Nicodem
Super Moderator
*******




Posts: 4230
Registered: 28-12-2004
Member Is Offline

Mood: No Mood

[*] posted on 4-5-2009 at 09:07


There is a thread where the dehydration of benzamide to benzonitrile was discussed and some references posted. I take it that you did use the search engine and checked that out before asking, so here is what I found:

Chem. Listy 97 (2003) 1079-1082 give up to a 69% yield for this reaction (they get some of the trimeric product as well). I don't understand Czech, so you might want to use machine translation on that and, of course, also follow their references for this particular reaction since they made a literature review in the introduction section.

Then there is also a three sentence long experimental in patent US6617454:
Quote:
EXAMPLE 32

Regeneration of Benzonitrile From Benzamide

A two-necked flask was charged with of benzamide (0.0054 mol) and phosphorous pentoxide (1.2 g) in 10 ml of methanol. The mixture was stirred for 1 h at room temperature. After the completion of the reaction (followed by TLC), the mixture was concentrated on a rotovapor and benzonitrile was obtained quantitatively by vacuum distillation.


In my opinion the simplest method (for the amateurs) is described in Zhurnal Organicheskoi Khimii, 23 (1987) 1799 (there is also the English version of this journal, as far as I know). They use H2SO4 in acetonitrile to dehydrate benzamide (or other amides) while the acetonitrile gets hydrated.
View user's profile View All Posts By User
turd
International Hazard
*****




Posts: 800
Registered: 5-3-2006
Member Is Offline

Mood: No Mood

[*] posted on 4-5-2009 at 11:18
Phenylpropanolamine from alanine and benzoic anhydride


The thread on L-PAC got me thinking:
Wouldn't it be possible to obtain phenylpropanolamine by Dakin-West reaction between acetyl-alanine and benzoic anhydride, followed by reduction of the ketone and saponification?

J. Am. Chem. Soc., 1950, 72 (7), 3200-3203 says that reaction between benzoic anhydride and amino acids is slow and low yielding.
But in J. Org. Chem., 2003, 68 (7), 2623-2632 they claim a 73% yield with 3 eq. of benzoic anhydride in pyridine at 90°, but on a completely different substrate.

So?
View user's profile View All Posts By User
User
National Hazard
****




Posts: 339
Registered: 7-11-2008
Location: Earth
Member Is Offline

Mood: Passionate

[*] posted on 5-5-2009 at 11:20


I was wondering/wandering..

I could wel be that this is covered already.

I have nitric acid with a concentration of 53%.
Now i would like to bring up the concentration to azeotropic forming.
Well as far as iam concerned this can be achived by boiling it down.
The last time ive done this the fumes where acidic even before the 68% is reached, so this means loss of HNO3.

Could it be a nice idea to put my vigreux (60cm in length) on top so only the highest boiling fraction steams off?
Anyone any ideas on this, i thought it might be a neat trick.

regards, user




What a fine day for chemistry this is.
View user's profile View All Posts By User
hissingnoise
International Hazard
*****




Posts: 3940
Registered: 26-12-2002
Member Is Offline

Mood: Pulverulescent!

[*] posted on 5-5-2009 at 11:47


Quote: Originally posted by User  

Could it be a nice idea to put my vigreux (60cm in length) on top so only the highest boiling fraction steams off?
Anyone any ideas on this, i thought it might be a neat trick.

The lowest boiling fraction will boil off first. . .
It would be simpler to distill from H2SO4 and dilute afterwards.
Ooops!
Sorry User, I wasn't thinking---the solution will lose water until the azeotrope is reached. . .

[Edited on 5-5-2009 by hissingnoise]
View user's profile View All Posts By User
User
National Hazard
****




Posts: 339
Registered: 7-11-2008
Location: Earth
Member Is Offline

Mood: Passionate

[*] posted on 5-5-2009 at 12:13


Damn your right, man that was dumb.
The point is that a vacuum source is still a pain in the ass.

[Edited on 5-5-2009 by User]




What a fine day for chemistry this is.
View user's profile View All Posts By User
hissingnoise
International Hazard
*****




Posts: 3940
Registered: 26-12-2002
Member Is Offline

Mood: Pulverulescent!

[*] posted on 5-5-2009 at 12:25


Let's see if I can get it right this time, User---your dilute HNO3 contains water and the azeotrope which boils at ~120.5, making water the lowest-boiling fraction. . .
View user's profile View All Posts By User
User
National Hazard
****




Posts: 339
Registered: 7-11-2008
Location: Earth
Member Is Offline

Mood: Passionate

[*] posted on 5-5-2009 at 13:20


I am not making myself real clear i guess, sorry 4 that.
The vapor coming from the boiling down mixture (which hasnt reached azeotrope) can be measured acidic with a piece of PH paper, so i figured HNO3 is lost.
To what extend is not really measurable by this method.

Has anyone destillated H2SO4/HNO3 under normal pressure with good results?


Would it be an idea to destillate HNO3 with sulfuric acid and afterwards boiling down the sufuric acid so that it is recovered.
And there would be no actual loss of chemicals.





What a fine day for chemistry this is.
View user's profile View All Posts By User
hissingnoise
International Hazard
*****




Posts: 3940
Registered: 26-12-2002
Member Is Offline

Mood: Pulverulescent!

[*] posted on 5-5-2009 at 13:37


Your post was quite clear, User, it was I who got diverted. . .
Using a column should minimise HNO3 losses, but they should be small, anyway, and more or less unavoidable!
The H2SO4 route isn't actually necessary, after all.
When the azeotrope is reached, the temp. will go up.
View user's profile View All Posts By User
Sedit
International Hazard
*****




Posts: 1939
Registered: 23-11-2008
Member Is Offline

Mood: Manic Expressive

[*] posted on 8-5-2009 at 07:19


I have some old Manganese welding rods that I was going to toss out. Does anyone have any suggestions as to what use they could be put to and what the other contents of these maybe?




Knowledge is useless to useless people...

"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story before."~Maynard James Keenan
View user's profile View All Posts By User
DJF90
International Hazard
*****




Posts: 2266
Registered: 15-12-2007
Location: At the bench
Member Is Offline

Mood: No Mood

[*] posted on 8-5-2009 at 09:15


Thats something I've never heard of before! Are they for welding manganese? (Who builds anything out of manganese lol :S). Perhaps you could use them to make manganese salts? pretty boring to be honest but I cant think of much else manganese can be used for. As to other contents in the rods... There is likely to be some kind of flux to help keep the weld pool from being oxidised, and the manganese might be alloyed for better mechanical properties.
View user's profile View All Posts By User
Sedit
International Hazard
*****




Posts: 1939
Registered: 23-11-2008
Member Is Offline

Mood: Manic Expressive

[*] posted on 8-5-2009 at 11:00


:) I have no idea what there for they came with an old welder I got for junkin a while ago. I was clearing my garage the other day and found a ton of them. Its either toss them out for make something of it. I was considering MnOx but the fluxes are my main concern because if there is some contaminations I want to know what they are.




Knowledge is useless to useless people...

"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story before."~Maynard James Keenan
View user's profile View All Posts By User
DJF90
International Hazard
*****




Posts: 2266
Registered: 15-12-2007
Location: At the bench
Member Is Offline

Mood: No Mood

[*] posted on 8-5-2009 at 12:54


Could you not purify the metal like they do with copper using electrolysis? The impure manganese ionises to form Mn2+ (I expect) and then deposit on a small piece of pure manganese used as the other electrode (needs to be anode).
View user's profile View All Posts By User
Intergalactic_Captain
Hazard to Others
***




Posts: 228
Registered: 4-9-2004
Location: somewhere where i don\'t know where i am
Member Is Offline

Mood: frabjous

[*] posted on 11-5-2009 at 09:31


Are there any shipping regulations (in the continental US) on ammonium iodide? I picked up a pound of Malinkrodt AR grade as the price was right, but it's way more than I need - I'd like to repack and resell it on ebay (or here, PM me if interested)... I'm guessing its either unregulated or ORM-D, but I can't find any solid info.



If you see me running, try to keep up.
View user's profile View All Posts By User
kclo4
International Hazard
*****




Posts: 915
Registered: 11-12-2004
Location:
Member Is Offline

Mood: No Mood

[*] posted on 11-5-2009 at 19:03


From what I know in chemistry, it seems like one could react Sodium Methyl Sulfate with Sodium phenolate to produce methoxybenzene, do you think this is true?
The producure on orgsyn to produce methylbenzene uses DMS and sodium phenolate, and claims sodium sulfate is produced in the end. I'm guessing sodium methyl sulfate is an intermediate in that reaction, and so I guess that gives me reason to believe, or at least gets my hopes up that it will work.

I have been meaning to try it, but I haven't got the time and figured I might as well ask.

EDIT: Well I'm a damn fool!
it says it works on the orgsyn document.
Sorry about that, but hey I guess I brought it to your attention that phenols can be methylated with the easily prepared sodium methyl sulfate!


[Edited on 12-5-2009 by kclo4]




View user's profile Visit user's homepage View All Posts By User
Nicodem
Super Moderator
*******




Posts: 4230
Registered: 28-12-2004
Member Is Offline

Mood: No Mood

[*] posted on 12-5-2009 at 00:18


Kclo4, please UTFSE. This has already been discussed and there are a few literature examples posted at this forum.
View user's profile View All Posts By User
Panache
International Hazard
*****




Posts: 1290
Registered: 18-10-2007
Member Is Offline

Mood: Instead of being my deliverance, she had a resemblance to a Kat named Frankenstein

[*] posted on 12-5-2009 at 16:04


Two Questions

1) Cation exchange Resins
I have some acidic resin that i want to use to make some HI from KI. I have already performed a quick try and it worked fine, however a dilute KI solution was used. I don't have the solubility of KI at RT, but at 0C its 127.5g/100cc H20 and this increases to 210g at 100C.
Assuming linearity, this gives me a solubility around 150gKI/100c H20 at 25C. At this concentration one should be obtaining near azeotropic HI out of the bottom of the column (well ~54%HI).

That is the background.

My question is, would it be normal procedure to exchange the cation using such a saturated solution (and hence save time and material losses in distilling the HI to 57%) or am i going to run into problems doing this exchange and hence would be better off running at say 10% and doing a more tedious distillation? Any thoughts?

2) Citric acid solution (~10%) (further acidified with ~3%HCl) and 50% H202 reacts quite vigorously after a few minutes onset. Gas evolution occurs with heat evolution and the slight yellowness of the solution clears completely to water clear. What is going here? I assume the citric is simply forming the per-acid, which because of the condensed structure of the tri-carboxylic acid is inherently unstable and decomposes rapidly evolving oxygen. I tried to find some literature on forming per-citric acids but found none. (disclaimer-i din't look really hard). If my supposition is plausible am I reasonable in perhaps supposing then that the percitric acid could be a more active per-acid than the typical per-formic and per-acectic, (solutions of which can be stablised enough to make them shelf stable.) My question pertains mainly to per-acetic acids' excellent ability to disinfect. Solutions of said are commonly used in wash downs in the food industry.

[Edited on 13-5-2009 by Panache]




View user's profile View All Posts By User
UnintentionalChaos
International Hazard
*****




Posts: 1454
Registered: 9-12-2006
Location: Mars
Member Is Offline

Mood: Nucleophilic

[*] posted on 12-5-2009 at 16:23


I'd suspect that the per-citric acid may form, but decomposes, ejecting O2 and CO2. I would suspect that the citric acid is completely consumed in the process with things like the very oxidation-prone acetone dicarboxylic acid being generated as intermediates.

Keep in mind that the HCl will generate HClO and Cl2 with the H2O2. Perhaps you should test it with dilute H2SO4 instead.

[Edited on 5-13-09 by UnintentionalChaos]




Department of Redundancy Department - Now with paperwork!

'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
View user's profile View All Posts By User
Panache
International Hazard
*****




Posts: 1290
Registered: 18-10-2007
Member Is Offline

Mood: Instead of being my deliverance, she had a resemblance to a Kat named Frankenstein

[*] posted on 12-5-2009 at 16:37


Quote: Originally posted by UnintentionalChaos  
I'd suspect that the per-citric acid may form, but decomposes, ejecting O2 and CO2. I would suspect that the citric acid is completely consumed in the process with things like the very oxidation-prone acetone dicarboxylic acid being generated as intermediates.

Keep in mind that the HCl will generate HClO and Cl2 with the H2O2. Perhaps you should test it with dilute H2SO4 instead.

[Edited on 5-13-09 by UnintentionalChaos]


Apologies i should have mentioned the evolved gas was colourless and without odour.




View user's profile View All Posts By User
 Pages:  1    3    5  ..  30

  Go To Top