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gdflp
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Quote: Originally posted by Argentum  | Question
Is there any way of recognizing sulphuric acid without using a pH-meter or pH paper?
It's from a liquid drain cleaner, it should be H2SO4 but I'd like to be sure.
No, the label doesn't says the content of the bottle.
Thanks! |
Are you assuming that it's concentrated? If so, place a few drops on some paper, sugar, or other organic material and wait for a few seconds. If
quickly turns black, then it is most likely sulfuric acid. This occurs because the sulfuric acid rips the organic material apart and dehydrates it,
leaving carbon.
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Metacelsus
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If you mix it with an iodide salt, you should get iodine and sulfur dioxide/sulfur/hydrogen sulfide (reduction products of sulfuric acid).
Other strong acids can dehydrate organic matter, but gdflp's test is generally good.
Alternatively, add a soluble barium salt, and look for a precipitate. This will rule out some acids like nitric and hydrochloric (but not phosphoric).
[Edited on 5-2-2015 by Cheddite Cheese]
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math
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Question:
can I safely put a small butane canister (lighter refills) at -15°C for some hours then expect to take it out and pour liquid butane out of it by
pushing the valve (as usually done when filling a lighter) ?
Thank you 
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Zombie
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Short answer is no. Not really.
Butane evaporates so quickly in air that you really have to keep it contained.
I suppose you could open the can in a -15* C environment, and potentially transfer it into another frozen container but simple things like body temp
would cause it to boil off. Then there is the vaporization in air... It's really not practical unless the goal is to switch sealed containers. Then
the answer would be yes. As long as it is maintained.
Edit: By "pushing the valve" the flow rate would be too slow, and the exposure to air would dissipate it. Soooo Back to no. For that method.
[Edited on 6-2-2015 by Zombie]
They tried to have me "put to sleep" so I came back to return the favor.
Zom.
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Loptr
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Will hydrolysis of acetamidine eventually lead to its acid, acetic acid?
I am jumping around in my old textbook, and I am not sure if amidines behave differently. I have found reference to them being easily hydrolyzed, but
just not to what extent.
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math
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Do alcohols get more expensive (mole-wise, seems more comparative than weight- or volume-wise) the longer the carbon chain gets?
So, is isopropanol cheaper than butanol, pentanol and cetyl alcohols?
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Zombie
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It all depends on the manufacturing process. Some are easier to produce than others.
Pricing is easy...
https://www.spectrumchemical.com/OA_HTML/index.jsp?minisite=...
http://www.hobbychemicalsupply.com/
[Edited on 6-2-2015 by Zombie]
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Loptr
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| Quote: Originally posted by math | Do alcohols get more expensive (mole-wise, seems more comparative than weight- or volume-wise) the longer the carbon chain gets?
So, is isopropanol cheaper than butanol, pentanol and cetyl alcohols? |
Cetyl alcohol
http://www.soapgoods.com/Cetyl-Alcohol-palmityl--p-675.html
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Loptr
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| Quote: Originally posted by Loptr | Will hydrolysis of acetamidine eventually lead to its acid, acetic acid?
I am jumping around in my old textbook, and I am not sure if amidines behave differently. I have found reference to them being easily hydrolyzed, but
just not to what extent. |
To answer my own question, yes it will.
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Zombie
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| Quote: Originally posted by Loptr | | Quote: Originally posted by Loptr | Will hydrolysis of acetamidine eventually lead to its acid, acetic acid?
I am jumping around in my old textbook, and I am not sure if amidines behave differently. I have found reference to them being easily hydrolyzed, but
just not to what extent. |
To answer my own question, yes it will. |
I see how you did that.
They tried to have me "put to sleep" so I came back to return the favor.
Zom.
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Argentum
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| Quote: Originally posted by gdflp | | Quote: Originally posted by Argentum | Question
Is there any way of recognizing sulphuric acid without using a pH-meter or pH paper?
It's from a liquid drain cleaner, it should be H2SO4 but I'd like to be sure.
No, the label doesn't says the content of the bottle.
Thanks! |
Are you assuming that it's concentrated? If so, place a few drops on some paper, sugar, or other organic material and wait for a few seconds. If
quickly turns black, then it is most likely sulfuric acid. This occurs because the sulfuric acid rips the organic material apart and dehydrates it,
leaving carbon. |
Nothing happened. Maybe it's muriatic acid, it looks like cheap hardware store muriatic acid.
Another question. Is cornstarch (the one sold in supermarkets) relatively pure starch?
Thanks
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Zombie
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Not really.
They are all going to contain at least some Iron, Ash to prevent clumping, and some Sulfur Dioxide from processing.
This applies to Pharmaceutical grade. Grocery or Food Grade will have much higher PPM.
I would stick to Pharma grade if purity is a concern.
They tried to have me "put to sleep" so I came back to return the favor.
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The Volatile Chemist
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If I boil a solution of Urea to saturation, and ammonia is able to be smelled coming off the beaker, how much has turned to biuret? Like, most of it,
or almost none of it? (Or in between, I'm looking for 'about's here).
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Loptr
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| Quote: Originally posted by The Volatile Chemist | | If I boil a solution of Urea to saturation, and ammonia is able to be smelled coming off the beaker, how much has turned to biuret? Like, most of it,
or almost none of it? (Or in between, I'm looking for 'about's here). |
I would argue that if you are using fertilizer grade urea, there is already biuret in the mixture. 
* Note: I have read that biuret is a common impurity in OTC urea. Source: Somewhere in the google-sphere.
If you heat Urea above its melting point, and smell ammonia, then you have likely produced some biuret. Whether this is the only product, I can't say
at this time.
http://en.wikipedia.org/wiki/Biuret#Preparation
[Edited on 9-2-2015 by Loptr]
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Sulaiman
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math;
I use a combination of liquid and gaseous butane as a dielectric for one of my high voltage probes (P6015) and the answer to your question is YES.
I don't pre-cool the butane canister or the vessel that it will go into
and I do this indoors though outdoors would be wiser.
Just invert the butane can and depress the nozzle with pliers
(to avoid freezing your fingers)
squirt the liquid butane into your vessel
initially some liquid butane will boil off, cooling the receiving vessel,
then the vessel will begin to fill with liquid butane.
It's true that ambient heat will slowly boil the liquid butane
but the vapour pressure is about two atmospheres at room temperature
so it doesn't take much to seal your vessel and prevent boiling.
e.g. my probe is an aluminium tube sealed with a rubber compression washer,
I last re-filled it over two years ago and there is no sign of loss of liquid butane (the bottom of the probe is transparent plastic)
I have not tried but I expect that a rubber bung would seal a test tube of liquid butane at room temperature.
Update, just went to my lab/shed (presently c5 celcius!) for a quick test
no observable boiling in a glass vessel open to the air,
so I poured the liquid butane into a small plastic bottle and screwed the cap on .. not enough pressure to bulge the bottle.
BEWARE: the vapour pressure increases rapidly with temperature
see this wikipedia page http://en.wikipedia.org/wiki/Butane_(data_page)
and look at the graph 'Vapor pressure of n-butane'
/just did a bit of googling ...
a 2 litre coke bottle containing some liquid butane would probably burst if immersed in boiling water, so don't do that !
but it does indicate that at room temperature it should be ok.
[Edited on 10-2-2015 by Sulaiman]
[Edited on 10-2-2015 by Sulaiman]
[Edited on 10-2-2015 by Sulaiman]
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The Volatile Chemist
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| Quote: Originally posted by Loptr | | Quote: Originally posted by The Volatile Chemist | | If I boil a solution of Urea to saturation, and ammonia is able to be smelled coming off the beaker, how much has turned to biuret? Like, most of it,
or almost none of it? (Or in between, I'm looking for 'about's here). |
I would argue that if you are using fertilizer grade urea, there is already biuret in the mixture.
* Note: I have read that biuret is a common impurity in OTC urea. Source: Somewhere in the google-sphere.
If you heat Urea above its melting point, and smell ammonia, then you have likely produced some biuret. Whether this is the only product, I can't say
at this time.
http://en.wikipedia.org/wiki/Biuret#Preparation
[Edited on 9-2-2015 by Loptr] |
Thanks. It [the urea] is from driveway salt, one brand sells pet-safe stuff which is supposedly all urea. Of course, it has dye in it, but I found the
dye is very soluble in isopropanol, thus I have been able to remove about 75-80% of the dye from the 'salt', and have turned it into a more
crystalline form.
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Sulaiman
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Please excuse these noob questions but
Is there any kind of machine that can reliably identify all known compounds in a mixture?
and determine absolute amounts of each compound in the mixture?
On a more realistic level, at least all common pharmaceutical compounds.
Or at least,
is there some machine that can detect the presence of unlisted compounds in medicinal mixtures.
Potentially this would be for a commercial testing facility for food supplements etc,
(and probably a service to aid hospitals etc. in diagnoses
and other customers to be determined)
P.S of course a noob like me would not be the operator,
some kind of pharmacists/chemists would need to be hired and trained by the vendor(s) of this magic machine or suite of machines.
OR
which are the leading manufacturers of similar equipment?
[Edited on 14-2-2015 by Sulaiman]
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fluorescence
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Well I think there is no machine that can just look at it and tell you what it's made of.
But there are other possibilities. From NMR, IR to Mass spectrometry.
I have never really worked with them but they can show you the presence of functional groups.
It takes some time to read the diagramms but you could compare the signals to known substances and
so find out what a pharmaceutical compound is made of.
I've seen this documentation on new drugs since it is theoretically allowed to make something that resembles
a drug listed compound and then change some functional groups till you get a new molecule that is not enlisted.
On TV they bought some of this stuff and gave it to a laboratory and they were able to determine the structure.
So I'd say you can find out most of the molecular structure of a given compound but it might depend on what
machine you are using.
But as said, I'm no expert on this either, I might be wrong here.
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Metacelsus
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GC/MS might be your best bet, but even it has limitations.
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Chemosynthesis
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The pharmaceutical industry uses literally every analytical instrument type manufactured. It just depends what you are doing specifically. GC/MS is
arguably the leading analytical test for things such as confirmatory drug testing in criminal cases (dealing, manufacture, sports doping). You have to
know what you are looking for, though.
Adjunct confirmatory testing is often done with an IR or similar. Those two are how a local crime lab prefers to do business. In the actual
pharmaceutical industry, NMR and IR spectra of each individual synthetic intermediate is taken, among other tests, and can be requested. Additional
testing is often done.
The final pharmaceuticals tend to have USP-NF certified HPLC testing done, which is probably still the most common quantitative QC test in the
pharmaceutical industry.
Individual instruments can vary, sensors vary, etc. Someone trained on an Agilent can't necessarily use a Waters. I'm not sure what to expect with NMR
now, as Agilent bought Varian a few years back, and now both are exiting the NMR market. If this is a legitimate work thing, you need to just ask the
employees what they need, and then start talking to regulatory agencies or start calling competitors/service providers and just ask what they use and
why they think it's better than some other guy.
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Sulaiman
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That's the answer that I expected but didn't want,
so there is no universal analyser,
it is/was a potential business opportunity in a South East Asian country,
via relatives (I certainly could not afford the start up costs)
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Chemosynthesis
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One complication to keep in mind with overseas work is the labor force. Some standards of testing and regional markets may be different both in terms
of employees and equipment.
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battoussai114
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Are there any IR sources used in IR Spectrometry other than heated inert materials?
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j_sum1
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Question: Slightly confused about carbon zinc battery.
I have disassembled a few lantern batteries -- for electrodes and other useful things.
First step in purifying the MnO2 paste is to mix with water to form a slurry and then filter. The intention is to dissolve the ZnCl2 or NH4Cl that
acts as an electrolyte.
The other day I ran a current through it and discovered to my surprise that a nice grey metal plated out on the cathode. I thought I had a solution
of ZnCl2 but of course Zn cannot be electrolytically reduced in aqueous solution. So, what is it that plated out? Do some batteries contain tin
compounds or bismuth or something else strange? What is it that I have got?
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quantumcorespacealchemyst
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What is the white frost on glass from being near HCl(aq)?
What is the white frost on glass from being near HCl(aq)? It is wipable, smells odd and forms even near sealed acid containers. It seems to certainly
be from HCl gas. What it is, I don't know.
[Edited on 22-2-2015 by quantumcorespacealchemyst]
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