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DraconicAcid
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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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Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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Sulaiman
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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 
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 
[Edited on 1-2-2018 by Sulaiman]
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DrP
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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 |
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.
\"It\'s a man\'s obligation to stick his boneration in a women\'s separation; this sort of penetration will increase the population of the younger
generation\" - Eric Cartman
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Sulaiman
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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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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.
\"It\'s a man\'s obligation to stick his boneration in a women\'s separation; this sort of penetration will increase the population of the younger
generation\" - Eric Cartman
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Sulaiman
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| 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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yobbo II
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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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| 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.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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ninhydric1
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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?
The philosophy of one century is the common sense of the next.
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DraconicAcid
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| 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.....
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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ninhydric1
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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?
The philosophy of one century is the common sense of the next.
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TheNerdyFarmer
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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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JJay
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| 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 456 times
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Tsjerk
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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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ninhydric1
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Thanks, JJay. I should use a fake email for this, good idea.
The philosophy of one century is the common sense of the next.
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greenlight
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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
Be good, otherwise be good at it 
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Sulaiman
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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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ninhydric1
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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?
The philosophy of one century is the common sense of the next.
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j_sum1
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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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Bert
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Mood: " I think we are all going to die. I think that love is an illusion. We are flawed, my darling".
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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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Dr.Bob
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| 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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Dr.Bob
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| 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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Diachrynic
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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.
we apologize for the inconvenience
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Sulaiman
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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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learningChem
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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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