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Simbani
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Assumed I would like to distill (heavy, 6-12 C-atoms) naphta, what would be the best way to clean my flasks and condenser afterwards? I made some
experiences with a beaker full of thsi stuff and it was a pain to get it out there -.- I didn´t got it really clean till now.
Now what would be the easiest way to clean contaminated glassware, it should be easy to obtain tho. Is there some way to oxidize it, are they reactive
enough?
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elementcollector1
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Quote: Originally posted by Simbani  | Assumed I would like to distill (heavy, 6-12 C-atoms) naphta, what would be the best way to clean my flasks and condenser afterwards? I made some
experiences with a beaker full of thsi stuff and it was a pain to get it out there -.- I didn´t got it really clean till now.
Now what would be the easiest way to clean contaminated glassware, it should be easy to obtain tho. Is there some way to oxidize it, are they reactive
enough? |
Depends. For nonpolar substances, I'd recommend an initial cleaning with a nonpolar, evaporating solvent (such as gasoline, and away from any source
of heat, sparks, or open flame). Acetone works well in all situations, as does water in most. A final wash with water is necessary for all glassware
in my opinion, no matter the nature of the contamination.
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Simbani
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I tried acetone too, but it doesn´t work. I don´t know what is all in there accurately, but I know it is a mix of naphta (I think the heavy mix) and
pentane. I got the beaker relatively clean with soap-concentrate btw.
Isn´t there a chemical way to clean a distillation apparatus? Like oxidating the little residudes which stick on the surface of the glass after
washing? H2SO4/H2O2, H2SO4/HNO3, HNO3/HCl, HNO3/H2O2?
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elementcollector1
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Piranha solution (I think it's H2O2/H2SO4 conc.) seems to be a good method, or most of the other ones you mentioned.
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darel
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Ampoule codes
I purchased a few small ampoules with a gold band where I assumed it is to be broken. I originally thought it was gold or some thin sheet of metal
that when heated would have broken the glass at that point on cooling due to thermal stress. Upon research I found it is color coding.
http://en.wikipedia.org/wiki/Ampoule#Ampoule_codes
http://link.springer.com/article/10.1007%2FBF03007733?LI=tru...
That was all I could really find. Does anyone know or have a table for what these codes are?
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Vargouille
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The bands aren't ampoule codes, they're indicating where the ampoules have been prescored. See here.
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smaerd
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So today in analytical chemistry I did a basic buffer solution preparation lab. Using the henderson hasselbalch equation and a phosphate buffer. I
prepared a series of pH buffers like 7.4, 7.6, 7.8, etc. Anyways When I measured the pH of these solutions they were off by like 0.20 for each. I know
I should probably just ask my professor but is that acceptable? It seems pretty far off... I think a lot of it may have to do with how moist the
phosphate salts were before becoming standards. Maybe also ionic strength?
[Edited on 8-2-2013 by smaerd]
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DraconicAcid
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| Quote: Originally posted by smaerd | So today in analytical chemistry I did a basic buffer solution preparation lab. Using the henderson hasselbalch equation and a phosphate buffer. I
prepared a series of pH buffers like 7.4, 7.6, 7.8, etc. Anyways When I measured the pH of these solutions they were off by like 0.20 for each. I know
I should probably just ask my professor but is that acceptable? It seems pretty far off... I think a lot of it may have to do with how moist the
phosphate salts were before becoming standards. Maybe also ionic strength?
[Edited on 8-2-2013 by smaerd] |
That's pretty typical. The H-H equation is an approximation (you're assuming that the concentrations that you put in are also the concentrations at
equilibrium), and ionic strength, as you say, is also a factor. If you want a particular pH, make an approximate one with your calculated buffer,
then adjust with acid or base until it's correct.
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gsd
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Esterification Question
If a mixture of 1 mole Ethanol, 1 mole 2-propanol and 1 mole 1-propanol is esterified with 1 mole of acetic acid then what is the likely distribution
of product (and why?)
gsd
[Edited on 8-2-2013 by gsd]
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DraconicAcid
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| Quote: Originally posted by gsd | Esterification Question
If a mixture of 1 mole Ethanol, 1 mole 2-ethanol and 1 mole propanol is esterified with 1 mole of acetic acid then what is the likely distribution of
product (and why?)
gsd |
I'm not sure that propanol would react much slower than ethanol in an esterification reaction, but I do have to wonder what you meant by "2-ethanol."
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gsd
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| Quote: Originally posted by DraconicAcid | ......
I'm not sure that propanol would react much slower than ethanol in an esterification reaction, but I do have to wonder what you meant by "2-ethanol."
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I am sorry. I meant 2-Propanol not 2-ethanol
gsd
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DraconicAcid
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I considered that possibility, but it could also have been 2-chloroethanol, etc., so I didn't want to assume. I would expect the product distribution
to depend on the rates of the reaction, and the rate will be determined by the nucleophilicity of the alcohols, and I would expect that to depend
slightly on the bulk of the organic group on the oxygen. But I'll let a *real* organic chemist offe a more definitive opinion.
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DJF90
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gsd: I did an esterification with isopropanol, and it took 18 hrs to reach 94% by HPLC. The methyl ester on the other hand, was formed under identical
conditions (apart from substituting iPrOH with MeOH) was complete (98%+) in 3 hrs. I dont know how well this answers your question, but I hope you
find it of use. I can't divulge the structure of the starting acid due to IP reasons, but its a substituted phenylacetic acid.
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smaerd
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Does anyone know how to go about doing a hydrolysis of a schiffs base that both it and it's products(aldehyde and amine) are pretty insoluble in
water?
I've tried steam distillation from aq. oxalic acid, tried refluxing from aq. sulfuric and neither seem to be near complete reactions. The steam
distillation carried over some of the suspected aldehyde which is great although a large amount of unreacted schiffs base remains at the bottom of the
boiling flask(2g of reactant to 75mL water carried over). Any tips would be exceptional.
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Boron Trioxide
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Question about Electrolysis:
Problems with Anodes:
Carbon, both graphite and activated carbon seem to share this problem, while they are conductive enough, they do not produce nearly any gas during
electrolysis as compared to the cathode which produces a fine continuous stream of bubbles, is there a reason and/or solution?
Thank you for your help
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elementcollector1
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Reason: 2 moles of hydrogen are produced per every mole of oxygen.
Chlorine is barely visible, and only occurs at high concentrations of chloride salt.
Sulfate simply doesn't bubble out as SO2 at all.
Elements Collected:52/87
Latest Acquired: Cl
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AJKOER
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| Quote: Originally posted by d010060002 | | The strongest concentration of ammonia that is pure and easy to get was 10%. A lot of the recipes I'm looking at require a more concentrated form. Has
anyone concentrated ammonia with good results using an easy method (boiling, freezing at a reasonable temperature). |
Two ideas:
1. Use Ammonium carbonate in place of aqueous NH3.
2. CaCl2.xNH3 where x = 2, 4 or 8.
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elementcollector1
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Can you heat a RB flask effectively on a flat hotplate? I'm thinking of doing the synth of K metal at my school, and want to use ground glass - but I
have no Erlenmeyers!
Alternatively, will rubber joints affect things?
Elements Collected:52/87
Latest Acquired: Cl
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DraconicAcid
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| Quote: Originally posted by elementcollector1 | | Can you heat a RB flask effectively on a flat hotplate? I'm thinking of doing the synth of K metal at my school, and want to use ground glass - but I
have no Erlenmeyers!? |
You can put a hot water bath on the flat hotplate, or an oil bath if you need a higher temperature.
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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Organikum
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Question
Would the use of formic acid salts of amines as ammoniumformate for example in the condensation of an aromatic aldehyde with a nitroalkene as
benzaldehyde and nitroethane, be problematic in any way in special possible esterification?
Always acetic acid, aren't there so much more organic acids? Thats how it started and now I am up to explore the possibilities. This condensation
looks like a good place to start with I thought and now I am looking for traps as my basic chemical is bad and I tend to overlook stuff which is
obvious for somebody who had chemistry in school for years.
If you know about sidereactions with formic acid/formate (or other organic acid, citric, oxalic and tartaric are next) pls tell.
regards
/ORG
PS: I start with ammoniumformate for I found an old HIVE posting by Hest which indicates he used it. Regarding his english and other things it might
be just a error/mismatch thats well possible.
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AJKOER
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| Quote: Originally posted by LiHMDS | Hi everyone!
I have a slightly stupid problem with some household - today I found my bottle of few kg bromine is pretty closed - glass stopper is stuck in this fn
bottle. I tried to carefully knock, turn etc, nothing helps. Is there any 'smart' way to open this joint taking on discount all situation?
[Edited on 1-7-2012 by LiHMDS] |
Freeze the whole bottle.
Carefully pour boiling water on just the joint.
Caution: The glass could crack, releasing come Br2, so do outside and wear appropriate safety gear.
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Vargouille
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Or, for a less dangerous way: freeze the bottle, then warm up the joint with a rag soaked in hot water from the tap. Wiggle the stopper back and forth
as you do so, but gently. No bromine should be airborne, but I would put a fan on just to be safe.
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dasgoose21
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How would I go about precipitating TACN from a very saturated solution of itself? I'm not very fond of the idea of putting it in a desicator for a few
days and then further drying out the paste with expensive acetone, so I am looking for a different way to pull the Tetra out of solution without going
through a lot of trouble.
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Eddygp
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What is the easiest, safest and most useful way for a home chemist to test for urea in a solution which might contain NH3 too?
there may be bugs in gfind
[ˌɛdidʒiˈpiː] IPA pronunciation for my Username |
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plante1999
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To test for urea, use oxalic acid, a precipitate will form if urea is present, ammonia do not interfere.
I never asked for this.
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