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Author: Subject: The Short Questions Thread (4)
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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Sulaiman
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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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[*] 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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Sulaiman
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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 5 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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