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DraconicAcid
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[*] posted on 31-1-2018 at 12:29


Quote: Originally posted by AJKOER  
Quote: Originally posted by j_sum1  
Does anyone routinely pyrolyse NaHSO4 to produce SO3? I am considering alternate routes to concentrated H2SO4. I do have some in stock and I have a good supplier. It is just that it is expensive whereas bisulfate is dirt cheap where I live.

I know the theory but with something like SO3 I would love advice from experience.


No experience on this experiment, but you may think about heating a mix of NaHSO4 with Fe powder in glass covered bowl in an old, disposable, microwave oven with short power burst only. Reference suggests the need for more equipment, see https://www.researchgate.net/publication/250012947_Microwave... also https://www.mri.psu.edu/sites/default/files/file_attach/135.... and more generally, http://aip.scitation.org/doi/abs/10.1063/1.2159078?journalCo... .

Needless to say, procedure can be extremely dangerous especially to eyes, lungs,...

[Edited on 31-1-2018 by AJKOER]


That might successfully heat the material, but you don't think that really hot sodium hydrogen sulphate will react with hot iron? That's probably the most dangerous (and least likely to work) suggestion I've seen on science madness lately.




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[*] posted on 1-2-2018 at 03:45
How accurate should a barometer be ?


I intend to re-configure my U-tube barometer to increase accuracy and durability.
I think that I understand the sources and remedies for most sources of error, it will be a matter of
How accurate does my barometer need to be for chemistry?
I realise that it is like 'how long is a piece of string ?'
so I would like to ask of anyone who has often used a barometer for chemistry in the 0 -1 atm range;

What is the most precision that has been required of a barometer ?
and Why ?




Thanks in advance :D





P.S. I ordered an EC Class 1 stainless steel ruler for the upgrade (+/- 0.1 mm/m error)(+/- 0.1 mm end error) that arrived Saturday ... bent in two places :mad:

[Edited on 1-2-2018 by Sulaiman]




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DrP
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[*] posted on 1-2-2018 at 03:57


Quote: Originally posted by Sulaiman  
I intend to re-configure my U-tube barometer to increase accuracy and durability.
I think that I understand the sources and remedies for most sources of error, it will be a matter of
How accurate does my barometer need to be for chemistry?
I realise that it is like 'how long is a piece of string ?'
so I would like to ask of anyone who has often used a barometer for chemistry in the 0 -1 atm range;

What is the most precision that has been required of a barometer ?
and Why ?




Thanks in advance :D



What are you using it for? Only time I really needed to measure pressure accurately was doing a reduced pressure distillation. I am not sure it needed to be that accurate for that anyway.




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Sulaiman
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[*] posted on 1-2-2018 at 05:02


Reduced pressure distillation is the main intended (and assumed) use.

I currently have three unregulated operating pressures;
c760 mmHg (atmosphere), c160 mmHg (mini-piston-pump) and <1mmHg (dual stage oil rotary).
I expect that ultimately I will need a way to measure <<1 mmHg but for now I want to do reduced pressure distillation of kerosene, and because I can, ethanol from sugar.
One of the few tools available to me for the identification of fractions is b.p. which is pressure dependant.
e.g. Suppose I have a fraction of kerosene with bp 200oC at 760 mmHg.
At 10 mmHg b.p. = 76.5oC
If the pressure was actually 9 mmHg then 76.5oC would imply b.p. 202.6oC @ 760 mmHg,
or if the pressure was actually 11 mmHg the bp at 760 mmHg would be 198.5oC
So a +/- 1 mmHg error at 10 mmHg leads to a +/-1.5oC error in bp at 760 mmHg.
This is almost acceptable for now, so my minimum acceptable accuracy will be +/- 0.5 mm in this specific case,
but what is a reasonable level of accuracy to aim for ?

I used this tool for the calculations https://www.sigmaaldrich.com/chemistry/solvents/learning-cen...




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DrP
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[*] posted on 1-2-2018 at 06:02


Quote: Originally posted by Sulaiman  
Reduced pressure distillation is the main intended (and assumed) use.

I used this tool for the calculations https://www.sigmaaldrich.com/chemistry/solvents/learning-cen...


I used to use the same chart from the back of the Sigma or Aldrich catalogues. :-)

Good luck with it - sorry I can't actually be of any help. I do not know how to measure it more accurately or if it needs it... So sorry for butting in, lol. I would say that if what you are doing is working then maybe it doesn't need to be so accurate... I would try to err on the side of being slightly below the desired pressure rather than over it and then the distillation should be easy.... but I think that you would probably have a lot more experience than I in doing what you are doing.:-) Good luck.




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[*] posted on 1-2-2018 at 09:57


Quote: Originally posted by DrP  
.... but I think that you would probably have a lot more experience than I in doing what you are doing.:-) Good luck.


If only !
I'm afraid I have read much more than I have done.





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[*] posted on 3-2-2018 at 12:37


I have a small quantity of nickle chloride with a much larger quantity of barium chloride dissolved in water.
There is a very slight green colour. How can I ppt the nickle? Reading up on solubilities i see that the hydroxide of barium is fairly soluble and nickel hydroxide is described as not soluble. Will adding some ammonia, filtering and then boiling to get rid of excess amonia do the triick.

Yob
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DraconicAcid
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[*] posted on 3-2-2018 at 13:03


Quote: Originally posted by yobbo II  
I have a small quantity of nickle chloride with a much larger quantity of barium chloride dissolved in water.
There is a very slight green colour. How can I ppt the nickle? Reading up on solubilities i see that the hydroxide of barium is fairly soluble and nickel hydroxide is described as not soluble. Will adding some ammonia, filtering and then boiling to get rid of excess amonia do the triick.

Yob

No, because ammonia will complex with nickel. You'd be better off precipitating the barium as the sulphate.




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Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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[*] posted on 3-2-2018 at 17:35


I've recently obtained a small amount of Ir powder for close to spot price, which is suspicious. Is there a quick and easy way to determine if it's truly iridium?



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[*] posted on 3-2-2018 at 18:42


Quote: Originally posted by ninhydric1  
I've recently obtained a small amount of Ir powder for close to spot price, which is suspicious. Is there a quick and easy way to determine if it's truly iridium?


I seem to recall that iridium *won't* dissolve in aqua regia, so that's one way to test.....




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[*] posted on 5-2-2018 at 19:21


I don't have access to the MSDS for Theochem Sulfuric Acid Drain Opener; it requires me to get an account which I detest. Anyone have a copy of it?



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[*] posted on 14-2-2018 at 04:51


Hello, so this is something that I have been thinking of for some time. If you plate a noble metal such as platinum onto a glass surface, will it make that surface inert to glass incompatible chemicals? I would of course have to fuse the coating to the glass.
I would trry it myself, but seeing as my platinum supply is so little and precious, same with nitric acid, I would like some feedback on if it could work or not. If someone here thinks that it may work, I will probably try it as soon as I make more nitric acid.
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[*] posted on 14-2-2018 at 16:34


Quote: Originally posted by ninhydric1  
I don't have access to the MSDS for Theochem Sulfuric Acid Drain Opener; it requires me to get an account which I detest. Anyone have a copy of it?


Here you go. I usually use Mailinator for throwaway email addresses, along with an obviously fake name like Anonymous User. By law, they can't really require you to create an account for an SDS.

Attachment: 16b8dd_e2b255ed8e9d4ef8a828fa20cf6d580b.pdf (328kB)
This file has been downloaded 32 times





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[*] posted on 15-2-2018 at 00:58


Does anyone know if there is a way to process THF into 1,4-butanediol? I searched a bit but could only find references for the reaction in the other direction.

Edit H2SO4 acid cleavage with water as nucleofil? OH- is probably not strong enough as a nucleofil is it?

[Edited on 15-2-2018 by Tsjerk]
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[*] posted on 15-2-2018 at 16:47


Thanks, JJay. I should use a fake email for this, good idea.



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[*] posted on 20-2-2018 at 19:03


Does anyone know of a synthesis writeup or any synthesis details for acetamide hydrochloride? I have been looking for a while and can't find anything:mad:




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[*] posted on 24-2-2018 at 01:54
Shelf life of pH buffers ?


My eBay pH meters came with sachets of buffer powder, pH 4.0 and 6.9.
I made up buffer solutions over two years ago, stored in airtight glass bottles.
Are these old buffer solutions likely to still be accurate ?


If not, could someone recommend long lasting diy buffer solutions suitable for pH probe callibration ?
(I have read a little on pH buffers but I don't know much about long term stability)




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[*] posted on 25-2-2018 at 21:44


https://www.ebay.com/itm/10-30g-Natural-Powdered-Cinnabar-Pi...

I feel like this isn't actual cinnabar, otherwise getting Hg easily would be too good to be true. Anyone have experience with this source?




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[*] posted on 25-2-2018 at 21:56


Quote: Originally posted by ninhydric1  
https://www.ebay.com/itm/10-30g-Natural-Powdered-Cinnabar-Pi...

I feel like this isn't actual cinnabar, otherwise getting Hg easily would be too good to be true. Anyone have experience with this source?

I have jad the same questions in the past. In some circles, cinnabar is a colour. I bought some cinnabar beads at one stage that looked suspiciously like plastic when they arrived. It is one of those things that is really hard to be certain of when browsing ebay.




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[*] posted on 25-2-2018 at 22:44


Well, the Chinese traditional medicine DOES use cinnabar, they do also make talismans and pigments for painting (used to use it for TATTOOING as well- Avoid the red designs, Yankee sailors!)

I suspect that some of these Chinese guys ARE selling actual mineral sourced or synthetic cinnabar, not just some random reddish stuff.

Handmade of natural mineral-cinnabar, mixed with refined castor oil and moxa. 

At the prices quoted, you could just buy a few items and see what comes in the mail...

Or buy it from westerners for more $s.

[Edited on 26-2-2018 by Bert]
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[*] posted on 26-2-2018 at 11:12


Quote: Originally posted by Tsjerk  
Does anyone know if there is a way to process THF into 1,4-butanediol? I searched a bit but could only find references for the reaction in the other direction.
Edit H2SO4 acid cleavage with water as nucleofil? OH- is probably not strong enough as a nucleofil is it?


Just add borane to it and let it sit a while. If you find an old bottle of BH3 in THF, it will likely be contaminated with 1,4-butan-diol, especailly if not stored cold. If you reflux the borane in THF, it will crack it even more. The best part is if you quench the reaction, then evaporate the THF< the diol will be the main thing left. You can always produce borane from NaBH4 and BF3 or some other lewis acid, in theory. But old borane in THF almost always contaminates your reaction with diol.
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[*] posted on 26-2-2018 at 11:17


Quote: Originally posted by Sulaiman  
My eBay pH meters came with sachets of buffer powder, pH 4.0 and 6.9. I made up buffer solutions over two years ago, stored in airtight glass bottles. Are these old buffer solutions likely to still be accurate ?

If not, could someone recommend long lasting diy buffer solutions suitable for pH probe callibration ? (I have read a little on pH buffers but I don't know much about long term stability)


Most are phosphate buffers or acetates, which are quite stable. All should be stable for years, the whole idea is that even if they change in concentration slightly, the pH should stay close to the labeled pH. I have used those solutions that were years old. And the pH meter is really only good to about 0.1 units most likely, so the buffer should stay within that much.
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[*] posted on 28-2-2018 at 13:37


My next project after extracting chromium and making dichromate is a (sodium) chlorate cell.

Quick question: If I run graphite anode, titanium or stainless steel (haven't decided yet) kathode, dichromate and pH-controlled at a current density of 17 mA/cm², how much anode corrosion do I have to expect? Is 17 mA/cm² even enough to make sodium chlorate? Is the corrosion in a potassium chlorate cell lower?

Thanks in advance.




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[*] posted on 2-3-2018 at 02:35


I'm finally going to titrate my drain unblocker sulphuric acid, say 95% w/w nominal.
What is the 'best' concentration to use for titration ?

I have previously used c1M solutions for titrations but since then I have read here that more dilute solutions may be better for accuracy.

I would like an answer accurate to +/- 0.25% using 0.2% worst case measurements of weight, volume etc.
============================
Dr.Bob ... thanks for the pH buffer quick answer.

[Edited on 2-3-2018 by Sulaiman]




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[*] posted on 2-3-2018 at 15:22
Induline analog?


Heating a mixture of aniline, aniline-HCl and nitrobenzene yields dyestuffs of the induline family. Would replacing nitrobenzene with nitrotoluene produce some sort of analog? (I may eventually try the reaction, but was wondering about the theory)

TIA!
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