Sciencemadness Discussion Board - The Short Questions Thread (4)

The Short Questions Thread (4)

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Ramium - 27-7-2016 at 00:15

@PHILOU Zrealone and Draconic acid

thanks for the responses. In the end I tried using acetone to force the complex out of solution. When I adding the acetone to the solution containing the complex, a blue precipitate formed. This substance seems to be insoluble in water but forms a fine suspension which looks like a solution.

I guess this can't be the complex then. Probably just copper hydroxide :mad:

wg48 - 27-7-2016 at 04:19

Quote: Originally posted by Ramium

@PHILOU Zrealone and Draconic acid

thanks for the responses. In the end I tried using acetone to force the complex out of solution. When I adding the acetone to the solution containing the complex, a blue precipitate formed. This substance seems to be insoluble in water but forms a fine suspension which looks like a solution.

I guess this can't be the complex then. Probably just copper hydroxide :mad:

From memory: the complex is soluble in methanol (my observation). It can be prepared in dry methanol in which sodium and glycerol are soluble. Presumable the powder is obtain by evaporation of the methanol. I don't know if the sodium hydroxide is required in excess. Probably less so in methanol than in water.

PHILOU Zrealone - 27-7-2016 at 05:26

Quote: Originally posted by Ramium

Instead of diethylether/ethanol, you may try plain isopropanol.

I don't understand why aceton would drop Cu(OH)2 from the glycerol complex...maybe aceton interacts a lot with glycerol.

Ethyl nitrate

gluon47 - 27-7-2016 at 23:16

I'm planning to make some ethyl nitrate soon using the method described here
http://www.prepchem.com/synthesis-of-ethyl-nitrate/

The ethyl nitrate is distilled out of the mixture. As a precuation, the nitric acid used is first boiled with urea to remove nitrous oxide.

But to me distilling ethyl nitrate still seems like a very risky thing to do.

Do I have reason to be concerned?

If I treat all nitric acid, with urea as described in the procedure, Will there still be a risk of an explosion?

Thanks in advance

Is electroysis the only way to make chlorine

smartgene - 1-8-2016 at 09:37

I was wondering is there another way to make chlorine from sodium chloride using a oxidant agent or something that is mild without using hcl or any acid

[Edited on 1-8-2016 by smartgene]

[Edited on 1-8-2016 by smartgene]

DraconicAcid - 1-8-2016 at 09:40

Potassium permanganate will work.

PHILOU Zrealone - 2-8-2016 at 09:35

Quote: Originally posted by DraconicAcid

Potassium permanganate will work.

Even without acid as requested?

I know KMnO4 and MnO2 works with HCl or with NaCl and an acid...but the question is about a way to make Cl2 without HCl / an acid.

smartgene - 2-8-2016 at 18:27

will peracetic acid work

Jstuyfzand - 3-8-2016 at 15:29

Can other metals their oxides be used as a catalyst in the contact process?
(At lower speed/efficiency)
Some sites mention "a metal oxide" catalyst to be used.

Cryolite. - 7-8-2016 at 00:20

I recently obtained a rather large amount of sodium hypophosphite monohydrate. Does anyone know of any interesting reactions I can do with this?

So far, I have:
- it can be used to dehydroxylate alcohols to the corresponding alkanes
- it can be used to reduce diazonium compounds to the unsubstituted derivatives
- with a radical initiator, it can be used to prepare phosphinic acids from alkenes
- it is a useful hydrogen source for transfer hydrogenations
- it has some interesting chemistry with copper salts (forming copper hydride among other things)

These are all very useful and interesting reactions, but my primary reason for purchasing it was as a source of reducing phosphorus which could substitute for red phosphorus. In addition to uses for hypophosphite itself, is anyone aware of a conversion from hypophosphite salts to phosphorus or, say, phosphorus halides?

[Edited on 7-8-2016 by Cryolite.]

PHILOU Zrealone - 7-8-2016 at 10:20

Lead nitrato hypophosphite complex is a sensitive primary explosive

US Patent nr 2327867

Filtering Tinctures - does it remove any active compounds?

RogueRose - 8-8-2016 at 19:37

I was wondering if tinctures of things like mint, black walnut, raspberry leaves, garlic, etc made with alcohol would have any active ingredients removed by running through a .45 or 1 micron filter?

PHILOU Zrealone - 9-8-2016 at 14:12

Quote: Originally posted by RogueRose

I was wondering if tinctures of things like mint, black walnut, raspberry leaves, garlic, etc made with alcohol would have any active ingredients removed by running through a .45 or 1 micron filter?

Most usual monomeric organic molecules are into the range of the nanometer...
To give you an idea H2O and N2 are about 1/3 of nanometer.
A nanometer is 10^-9 m so about 1/1000 of micrometer what is 10^-6 m
So even with a 0.45µm filter you are stil 450 times larger in diameter than a nanometer.
Only very large molecules/3D polymers would be stopped by it except if there is a very big affinity for the matterial of your filter and one of the consituents of the filtrate.

velocity of decomposition

shadow - 13-8-2016 at 18:16

I have been reviewing a publication named:

THE DECOMPOSITION OF CITRIC ACID BY SULFURIC ACID
BY EDWIN 0 . WIIG
RECEIVED\ AUGUST 11, 1930 PUBLISHED DECEMBER 18 , 1930

In the article, the author refers to the "velocity of decomposition", which is manipulated by using 4 different strengths of H2SO4.

He holds the temperature and pressure steady, and measures the amount of time that it takes for carbon monoxide to be produced.

I've not seen this measure in any other literature. Is it an outdated or unused measure?

I'm interested in the effects of the different strengths of H2SO4 on yield.

Thanks ahead,
shad

pepe - 14-8-2016 at 00:21

Perhaps the whole thing is a matter of etymology. Noticing that your cited publication was from the 1930's it very well could have meant velocity in a slightly different context than the current and precise definition we have arrived at since then. Looking at Websters 1828 dictionary we see that velocity has two entries. The first being a general relation to rapidity and swiftness and the second which is philosophically (not yet scientifically) affection of motion by which a body moves over a certain space in a certain time. Both of these definitions make me think that perhaps velocity was not so much then about the speed of a certain object of study but rather more related to the rate or speed at which things go.

Today the difference between speed (a rate regardless of direction) and velocity (as a vector quantity) is direction awareness. Perhaps this is our evolved understanding of the term and we suffer from this over complication when reading literature that regarded velocity in a simpler frame.

Much of this is speculation and would be quite cleared up if we could find a dictionary about 100 years newer than my reference but that was the only version I could readily access.

laserlisa - 15-8-2016 at 06:52

I have dried some ethanol using 3Å molecular sieves, and the ethanol has gotten quite cloudy because of what I assume is sieve dust. Does anyone have any tips on how to remove the cloudiness?

Also this zeolite dust is relatively inert I assume, but are there any reactions in which this dust might cause troubles?

Thanks

Cryolite. - 15-8-2016 at 13:01

Leave the ethanol to sit (over the sieves) for a few days. The dust will settle, and the dry ethanol can then be decanted off.

hissingnoise - 16-8-2016 at 00:57

Quote: Originally posted by gluon47

But to me distilling ethyl nitrate still seems like a very risky thing to do.

I had a runaway when I attempted to distill methyl nitrate ─ ethyl nitrate is higher boiling, has a lower OB and is markedly less brisant than NGl, EGDN or methyl nitrate!

All things considered, it doesn't have much bang for bucks!

PHILOU Zrealone - 16-8-2016 at 04:38

Quote: Originally posted by hissingnoise

Quote: Originally posted by gluon47

But to me distilling ethyl nitrate still seems like a very risky thing to do.

Following Rudolf Meyer-Explosives,Ed4- p131:
Ethyl nitrate has a VOD of 5800 m/s and a Lead block test of 420 ccm³/10g for a density of 1.1g/ccm³.
Vapour forms explosives mixtures with air at room temperature (lower explosion limit 3.8% Ethyl Nitrate)

It is stil a sensitive and powerful nitric ester...overheating during distillation is forbidden --> cold distillation or under vaccuum and in minute quantity.
Impact sensitivity must be between 0.2 and 3 Nm based on related nitric esters.

Copper acetate and iron reaction

artchemix - 16-8-2016 at 19:11

I made a copper acetate solution and used an iron wire to stir it. As soon as the wire touches the solution a thin layer of a black precipitate formed on the wire.

I left the iron wire on the solution for sometime and some bubbles appeared and the blue copper acetate solution slowly became discolored. I think this was a displacement reaction where the copper precipted out as small particles and iron acetate was formed. This is possible because copper is lower than iron in the reactivity series.

What amaze me the most was that I did not found any records of this reaction online. I want to know if my assumption is correct.

Thanks

DraconicAcid - 16-8-2016 at 19:47

Any copper(II) salt will react with iron. You are correct.

Velzee - 18-8-2016 at 08:16

Anyone know how to make the fictional gas, NOVA 6? No, but seriously, could it be a real substance? It is described as follows:

Quote:

According to the periodic table, the three basic elements in Nova 6 are Sulfur (S), Rhenium (Re) and Neodymium (Nd).

Nova 6 appears as a dark green gas. Upon inhalation, it causes vomiting, violent coughing, muscle convulsions, bleeding from the eyes, and blackening of the skin (necrosis), followed by an agonizing death within 10–20 seconds of exposure. In the more refined...form, Nova 6 retains its green color, albeit with a slight yellow tint, and has a much more instantaneous effect. Once inhaled, the victim suffers violent coughing, nausea, vomiting, suffocation, bleeding from the eyes, and scaling, burning skin, with death occurring before the body can even hit the ground.[1] This version has a 100% fatality rate,... the gas was tested on infants, causing death within 30 to 40 seconds.

DraconicAcid - 18-8-2016 at 10:09

Quote: Originally posted by Velzee

Anyone know how to make the fictional gas, NOVA 6? No, but seriously, could it be a real substance? It is described as follows:

Quote:

According to the periodic table, the three basic elements in Nova 6 are Sulfur (S), Rhenium (Re) and Neodymium (Nd).

There is no metal sulphide that could possibly be a gas under ordinary conditions.

PHILOU Zrealone - 18-8-2016 at 11:23

Quote: Originally posted by Velzee

Anyone know how to make the fictional gas, NOVA 6? No, but seriously, could it be a real substance? It is described as follows:

Quote:

Fictional it is fictional it remains...so unreal yes and as such you could do it fictionally by nuclear fusion...and exposition to gamma-rays from a super sun just before passing it through a black hole and distilling it out of a whorm hole with a pinch of Jupiter clouds and ice from Europa...

More realistically:
If the solid matter is nanosized, then it could become airbone and remain in suspension thanks to Brownian move of surrounding gas molécules...but on itself not a gas a such.

[Edited on 18-8-2016 by PHILOU Zrealone]

Velzee - 20-8-2016 at 01:32

Hmm..could oxalic acid be used to produce nitric acid, or would it just be oxidized as HNO3 is produced?

DraconicAcid - 20-8-2016 at 08:36

Quote: Originally posted by Velzee

Hmm..could oxalic acid be used to produce nitric acid, or would it just be oxidized as HNO3 is produced?

Depends on what concentration you want. I assume you mean to react calcium nitrate with oxalic acid in a precipitation reaction, to leave nitric acid in solution, or something to that effect. It will probably work fine if the concentration is less than 1 mol/L or so.

math - 23-8-2016 at 05:47

Which (safe) experiments could be done with a veterinary X-ray generator (plus phosphor screens), apart imaging objects conventionally (projecting their shadow in radiographs)?

Thank you

[Edited on 23-8-2016 by math]

zwt - 23-8-2016 at 06:26

Make an electroscope radiation meter and watch it droop.

I cannot assess the safety of this, x-rays scared even Edison.

Which of these has general or interesting use ?

Sulaiman - 23-8-2016 at 06:48

I am planning to make a 'fruity' ester following videos by NileRed and others,
the alcohols are not cheap, for me, with p&p, price per litre;

1-propanol £11.95
Benzyl Alcohol £14.25
1-octanol £24.20
1-nonanol £266.10
2-pentanol n/a

are any of the first three generally useful/interesting ?

EDIT: math
You could investigate different doses on biological specimens,
living plants, seeds, bugs, muscle tissue ....

[Edited on 23-8-2016 by Sulaiman]

DraconicAcid - 23-8-2016 at 07:42

Quote: Originally posted by Sulaiman

I am planning to make a 'fruity' ester following videos by NileRed and others,
the alcohols are not cheap, for me, with p&p, price per litre;

1-propanol £11.95
Benzyl Alcohol £14.25
1-octanol £24.20
1-nonanol £266.10
2-pentanol n/a

I avoid benzyl anything as much as I can, and I'd expect propyl esters to be more volatile and fragrant than the octyl ones.

Sulaiman - 23-8-2016 at 16:49

Thanks.
I did a little research on the alcohols and propanol seems to be quite useful, and it is the cheapest.

Since a litre of 99.9% n-propanol is £12 incl. p&p
I wonder if there are syntheses where it can be used as a substitute for dry ethanol ?

DraconicAcid - 23-8-2016 at 17:08

Quote: Originally posted by Sulaiman

Thanks.
I did a little research on the alcohols and propanol seems to be quite useful, and it is the cheapest.

Since a litre of 99.9% n-propanol is £12 incl. p&p
I wonder if there are syntheses where it can be used as a substitute for dry ethanol ?

As a solvent, it will probably be an excellent substitute for ethanol. It won't dissolve ionic compounds as well as ethanol, but I doubt it would make much difference for most reactions.

Velzee - 23-8-2016 at 19:40

1,3-propanediol can be produced by the hydration of acrolein. If this is so, can the reverse reaction occur? And if so, how would one go about it?

j_sum1 - 23-8-2016 at 19:45

You want to play with acrolein??

Take care and good luck.

Velzee - 23-8-2016 at 20:16

Quote: Originally posted by j_sum1

You want to play with acrolein??

Take care and good luck.

Oh, no.. I better read the MSDS before anything... I didn't read up on the safety much because it's past midnight and I can barely keep my eyes open

EDIT: Looks like I'm not touching acrolein.

[Edited on 8/24/2016 by Velzee]

math - 23-8-2016 at 22:49

Quote: Originally posted by zwt

Make an electroscope radiation meter and watch it droop.

I cannot assess the safety of this, x-rays scared even Edison.

I see, thank you. Is there anything else imaging-related I'd try?

PHILOU Zrealone - 24-8-2016 at 03:29

Quote: Originally posted by Velzee

1,3-propanediol can be produced by the hydration of acrolein. If this is so, can the reverse reaction occur? And if so, how would one go about it?

Acrolein is CH2=CH-CH=O if you add water it would lead to HO-CH2-CH2-CH=O and if you add more water then to HO-CH2-CH2-CH(-OH)2 thus not to 1,3-propandiol...
To get 1,3-propandiol you also need a reduction (a partial hydrogenation).

Usually acrolein can be acheived in the lab from 1,2,3-propantriol (glycerine/glycerol)... and mild acid catalyst (NaHSO4).
HO-CH2-CHOH-CH2OH --> HO-CH2-CH=CH-OH + H2O
HO-CH2-CH=CH-OH <----> HO-CH2-CH2-CH=O (enol-keton equilibrium)
HO-CH2-CH2-CH=O --> CH2=CH-CH=O + H2O (favourized by the conjugation of the CC double link and the CO double link)

j_sum1 - 24-8-2016 at 03:55

Nilered has a recent video on acrolein from glycerine.
Fun to.watch but not fun to do.

As for the diol, I don't know. I have lots to learn. But undoubtedly there is a procedure. You might try prepchem.com.

math - 26-8-2016 at 14:39

Could a small license-free 60Co (or any other radioactive isotope of any kind) sample be used to obtain radiographs of objects comparable to those obtained by using a X-ray tube and phosphor plates?

Activated carbon's "selection" of what it can absorb

RogueRose - 29-8-2016 at 20:38

I've always wondered how AC works and what compounds will be absorbed by it.

So if there is some ammonium sulfate (say 1g/L) in water and the water is run through an AC filter, will it remover the AmmSulf? What about the same (1g/L) with a common chloride salt - Na, K, Mg or Ca?

aga - 30-8-2016 at 06:02

Activated carbon is basically carbon with a VAST surface area for atoms/molecules to get adsorbed onto.

Commercially they dose the AC with other chemicals to make them adsorb specific chemicals for specific applications.

Alice - 2-9-2016 at 10:37

Is there a possibility for a mixture of sodium hydroxide and magnesium metal, both powdered, to ignite spontaneously?

Hegi - 2-9-2016 at 12:03

Quote: Originally posted by Alice

Is there a possibility for a mixture of sodium hydroxide and magnesium metal, both powdered, to ignite spontaneously?

Yeah there is a possibility for the metal particles to ignite spontaneously, if the size is really small and surface area high, it´s called pyrophoricity.

Did it happen to you?

Alice - 3-9-2016 at 02:38

Thanks for the answer! No, nothing happend. I'm asking beforehand. I knew Mg powder is pyrophoric, the point is, if the mixture is somehow super-pyrophoric, for example due to the hygroscopicity of NaOH. Maybe it was a stupid question, because "powder" can mean a lot, and I should find out in some micro-scale experiment. On the other hand it's possible having ten times nothing and ignition in the eleventh trial. However, the case I was asking for is just a hypothetic worst case scenario compared to what I actually want to find out.

Hegi - 6-9-2016 at 12:18

Quote: Originally posted by Alice

Thanks for the answer! No, nothing happend. I'm asking beforehand. I knew Mg powder is pyrophoric, the point is, if the mixture is somehow super-pyrophoric, for example due to the hygroscopicity of NaOH. Maybe it was a stupid question, because "powder" can mean a lot, and I should find out in some micro-scale experiment. On the other hand it's possible having ten times nothing and ignition in the eleventh trial. However, the case I was asking for is just a hypothetic worst case scenario compared to what I actually want to find out.

I think there´s no such a reaction. I never heard of it.

Drying Sulfuric Acid to produce an anhydrous reagent

PTeLuM - 6-9-2016 at 14:52

Does anyone know of economical and reliable ways to dry 93% sulfuric acid drain cleaner? Would drying with anhydrous magnesium sulfate work, or maybe molecular sieves?

XeonTheMGPony - 6-9-2016 at 17:44

No sadly it is no where even remotely that simple sadly!

Only way is distillation/boiling/SO3 addition.

greenlight - 6-9-2016 at 20:56

I have a portable fumecabinet I have been using that I purchased from a high school which was upgrading to wall mounted fumehoods.
It has a large new activated carbon filter in it and I have clocked 33 hours on it so far mainly with acid fumes.
Does anyone have any idea how long these filters last before they reach their full absorbtion level and need replacing?

[Edited on 7-9-2016 by greenlight]

ficolas - 12-9-2016 at 12:29

I wanted to make food grade sodium acetate to use as a condiment, so I took vinegar, and sodium bicarbonate. I added some sodium bicarbonate to the vinegar until it stopped bubbling, then boiled the solution down. I got very contaminated sodium acetate, that tasted nicelly, but the vinegar I used wasnt distilled (keeping it food-grade), so it had some organic planty stuff that burned and ruined the sodium acetate (Im not eating brown shiet)
What can I do to stop this from happening?
I didnt use stoichiometric amounts because I dont know the concentration of acetic acid in the vinegar, and I currently have no good way of tritrating it (Only ph paper, I would need to use up a ton of them for a shitty tritation)

Or I could just use salt and vinegar as a condiment but that aint as fun.

Sulaiman - 12-9-2016 at 13:11

I'm guessing here but you could weigh out an ammount of sodium bicarbonate,
add vinegar until no fizzing (the last bit goes slowly, don't add vinegar too fast near the end)

you can work out the weight of sodium acetate produced,

look up the solubility and boil down only to that ammount then cool and hopefully collect moderately pure crystals.

ficolas - 12-9-2016 at 13:42

Thanks.
Im not usuing glassware, im using a steel pot.
Recrystalizatiom after the vinegar organic stuff burned didnt yield a pure product (I messed up quite a bit, it was my first recrystalization so probably it could be done better)
I'll try roughly calculating the amount of liquid in the pot using the liquid level, but ill probably get a very bad yield.

[Edited on 12-9-2016 by ficolas]

ficolas - 15-9-2016 at 10:29

I tried to crystalyce copper acetate into a big crystal dark crystal, like the ones seen here

(Image taken from SM btw)

But I can only get shitty small blue crystals.
I did get some dark ones starting to form in a copper wire, but a lot of blue ugly ones formed way faster.

What do I need to do to to get those beautiful crystals?
I thought about moving the evaporation thingie to a colder place, but that means it needs to be inside my house, something I dont think I can do. I also thought about hanging a copper wire, since I saw dark ones starting on the copper wire, but since its something that takes so long, asking saves me a lot of time

Question

zwt - 22-9-2016 at 09:57

What tests can be done to determine the level of nitrate contamination in ammonium perchlorate made from ammonium nitrate and sodium perchlorate? I'd imagine I could react away the ammonium with an excess of sodium hydroxide, and then reduce the nitrate to ammonia with aluminum, and then do a Kjeldahl titration of the ammonia, but I'm looking for something that doesn't require destroying large samples of the ammonium perchlorate. Is there any way to titrate for nitrate directly? This quote from the Wikipedia page "Nitrate test" gives cause for concern:

Quote:

The nitrate anion is an oxidizer, and many tests for the nitrate anion are based on this property. Unfortunately, other oxidants present in the analyte may interfere and give erroneous results.

[Edited on 23-9-2016 by zwt]

DraconicAcid - 22-9-2016 at 10:07

Quote: Originally posted by ficolas

I tried to crystalyce copper acetate into a big crystal dark crystal, like the ones seen here

(Image taken from SM btw)

But I can only get shitty small blue crystals.
I did get some dark ones starting to form in a copper wire, but a lot of blue ugly ones formed way faster.

What do I need to do to to get those beautiful crystals?
I thought about moving the evaporation thingie to a colder place, but that means it needs to be inside my house, something I dont think I can do. I also thought about hanging a copper wire, since I saw dark ones starting on the copper wire, but since its something that takes so long, asking saves me a lot of time

Make sure you've got excess acetic acid in solution. Don't leave the copper wire in there, as you'll get a slow reaction with atmospheric oxygen to give basic copper(II) acetate. I haven't had much luck with large beautiful crystals, but I tried leaving the copper wire in (actually, I was suspending the seed crystal from a copper wire, since I could tie it more easily than fishing line) and it failed, failed failed for that reason.

Aqueous formalin

Gemlingur - 26-9-2016 at 02:06

What would I expect from distilling a 37% formaldehyde solution? Is it an azeotrope?

hissingnoise - 26-9-2016 at 06:17

What's stopping you googling it?

Is this CuO or Cu2O??

RogueRose - 28-9-2016 at 18:52

The image doesn't show how black it is with lots of reflective "glitter like" speck in it. It is light and feels more like dry dirt.

I'm trying to figure out what I have here. It is the result of putting enameled copper wire (magnet wire) into hot (boiling at some points) molten NaOH. It leaned up the wire to a beautiful shine but there seemed to be some black specks in the lye and on the copper as I shook it off as I removed it from the pot.

I then soaked the copper w/ lye/black coating in hot water and boiled till clean. I added the water to the solidified lye until it was dissolved and filterable. The remainder is what is left from all the windings I "cleaned". There is about 1.25 cup and it weighs about 83-85g and it is fluff y like dirt. The thing is that I never had dirt near the lye or copper or solution pre-filter.

It has a dirt "feel" and a couple grains tasted like dirt. IT doesn't dissolve in water.

Any idea what this could be? Being so light how could it be copper (or is it some sodium compound)?

DraconicAcid - 28-9-2016 at 18:57

That might contain copper(II) oxide, but it doesn't look like it's even mostly copper(II) oxide.

Metacelsus - 29-9-2016 at 05:24

It's probably from the enamel.

Need help identifying this secondary alcohol!

Adipocerex - 29-9-2016 at 05:49

Can you guys help me identifying this orgo alcohol? Is it 2,3 dimethylpentanol? Or 2,dimethylhydroxypentanol.

https://scontent-arn2-1.xx.fbcdn.net/v/t34.0-12/14509282_102...
Thanks in advance

Texium - 29-9-2016 at 05:51

2-methyl-1,3-butanediol

Edit: to explain how to name it:

-Find the longest carbon chain that both hydroxyl groups are attached to, in this case, 4
-Number the carbons so that the substituents have the lowest numbers possible, in this case 1,2,3 (if you started at the other side it would be 2,3,4)
-Because there are two hydroxyl groups, it is classified as a diol

[Edited on 9-29-2016 by zts16]

Diethyl carbonate via sodium ethyl sulphate?

Ba(ClO3)2 - 30-9-2016 at 18:24

Would it be feasible to produce diethyl carbonate by dry distillation of sodium ethyl sulphate with sodium carbonate?

2 NaC2H5SO4 + Na2CO3 ==> (C2H5)2CO3 + 2 Na2SO4

The diethyl carbonate would be distilled off as it was formed leaving the sodium sulphate in the distilling flask.

If someone could confirm that this actually works, that would be great

Metacelsus - 30-9-2016 at 19:34

Possibly, but I wouldn't be surprised if you ended up with mostly ethylene gas (or diethyl ether).

Ba(ClO3)2 - 30-9-2016 at 20:49

ok, thanks anyway. we've got a very small amount of sodium ethyl sulphate which we want to use for something and we've always wanted to make some diethyl carbonate (not sure why, its just interesting stuff).

Does anyone have a good example of a simple and relatively safe runaway reaction?

j_sum1 - 6-10-2016 at 05:02

I am putting together a series of demonstrations on reaction rates for my students. One of the concepts that we have looked at is the general rule that reactions are often quick at first but then slow down as the reaction nears completion. But I want to show the students that there are counterexamples.

I don't want to get into any complicated theories on autocatalysis but I would like to show a reaction that demonstrates a thermal runaway. The best example that I can think of is solid state potassium permanganate and oxalic acid, but I would rather leave that one since I am using the solution version of that reaction for a different demo.

My preference would be something in a liquid phase that is latent for a while and then takes off after a minute or so as the temperature rises. Any suggestions?

elementcollector1 - 6-10-2016 at 05:10

I think a good alternative might be potassium permanganate and glycerin - if I recall, that one starts reacting slowly and then speeds up to conflagration in short order.

Another off the top of my head might be the 'carbon snake' demo, but this is tricky to do properly.

j_sum1 - 6-10-2016 at 21:29

I am still after answers to my question above. But in the meantime I have another one.

Has anyone had any experience in working with hebel? It is a kind of aerated cement product used in construction. It can (apparently) be easily cut and carved with hand tools. Specifically, I want to know how it will withstand high temperatures. I was considering constructing a kiln for small crucibles from a couple of hebel bricks: Probably using a propane torch or maybe a small charcoal fire.

I don't think it is designed as a firebrick but it is used as a firewall in architectural applications. So it can withstand at least some heat. I am attracted to it because it is cheap and readily available where I am and because I can quickly and easily carve it into the shapes I need. I envisage something made from 2 or 3 bricks that holds a 30mm crucible and can vent a nice hot flame around the crucible.

I know that a bit of experimentation will give me my answer but was fishing for some experience first.

NedsHead - 6-10-2016 at 22:05

I had the exact same idea J and picked up some hebel bricks a couple of weeks ago, it is extremely easy to work (soft and porous like honey comb) I initially tried to use it as the crucible when making the calcium carbide vie electric arc, it seemed to hold up under the temperature for the short time that I tried, my issue was when the product became molten it disappeared into the porous material.

I don't have much faith in it holding up under extreme temperature, or many heat cycles but maybe a soak in sodium/potassium silicate could improve its durability, something I’m yet to test, adding aluminium oxide powder to the mix might also help

j_sum1

Sulaiman - 7-10-2016 at 03:34

although not entirely safe,
the reaction between cold conc. HNO₃ and metals such as Cu and Ag
warns students of a common potential danger

it takes quite a while to start ... but when it does

this video shows the dangers of both runaway and suckback https://www.youtube.com/watch?v=pJSQq494oV4
use copper that is not too finely divided, e.g. a copper coin.

I also like glycerine + KMnO₄

[Edited on 7-10-2016 by Sulaiman]

Any interesting Beryllium chemistry ?

Sulaiman - 7-10-2016 at 07:41

I have some (yes I know it can be toxic) elemental berylium,
is there any interesting hobby-level beryllium chemistry that i can try ?

I have not found anything yet.

DraconicAcid - 7-10-2016 at 07:49

I'm under the impression that, other than its toxicity, beryllium chemistry is less interesting than aluminum.

Sulaiman - 7-10-2016 at 08:39

from what I've read so far Be and Al are chemically very similar,
even as part of catalytic compounds.
I'll just store it for now,
thanks.

DraconicAcid - 7-10-2016 at 08:59

Quote: Originally posted by Sulaiman

from what I've read so far Be and Al are chemically very similar,
even as part of catalytic compounds.

So much so that some of my really old books say that the best way to tell them apart is by tasting the compounds. Shudder.

Excess toluene for benzyl chloride synth

gluon47 - 16-10-2016 at 23:30

I'm planning to make a small amount of benzyl chloride sometime soon. The chlorination of toluene in the presence of UV light is definitely the easiest way for me. I plan to follow this procedure I found https://www.thevespiary.org/rhodium/Rhodium/Vespiary/talk/in...
I've heard a fair excess of toluene is needed, otherwise significant amounts of benzal chloride and benzotrichloride are also produced. In the procedure I linked to, a massive excess of toluene is used. Although the excess toluene is easily recycled, I would still prefer to use a minimum amount of toluene.

what I'm asking is, roughly what is the minimum % excess of toluene I could use without any significant amount of other products of higher chlorination forming?

Any advice would be much appreciated

.

[Edited on 17-10-2016 by gluon47]

Latent heat of fusion experiment

j_sum1 - 18-10-2016 at 16:33

I wish to have my students do an experiment that demonstrates latent heat of fusion. What I have in mind is to heat a solid to melting and then monitor the temperature as it cools and solidifies. What should be observed is a flat spot on the temperature-time graph that corresponds to the melting point. At this point the heat being released from the system comes from the phase change rather than a change in temperature.

I have done this before with naphthalene but as I recall the results were not amazingly clear. I am asking for suggestions for a material to use.

The ideal chemical would be:
something we have in stock
something that melts at a reasonable temperature -- 60°C would be ideal
something with a reasonably high latent heat of fusion
something that conducts heat well

I have considered water/ice but (a) boring and (b) I'd prefer a higher temperature
Gallium would be brilliant if we had buckets of the stuff
Sodium -- nice but ... nah. (Or should I say, "Na".) liquid sodium is not worth the risk assessment paperwork.
Tert butanol might be possible

Any other suggestions?

DraconicAcid - 18-10-2016 at 16:46

You may think water/ice is boring, but it works well. Measure the mass of some warm water, add some ice at 0 oC in an insulated container, measure the final temperature and total mass.

j_sum1 - 18-10-2016 at 16:56

Yeah except that is not the experiment I had in mind. I am less interested in a quantitative calorimetric measurement than a good visual demonstration of phase change. A flat line on an otherwise decreasing curve should do this well. We will do some calorimetry later (perhaps) and melting ice as you describe is a likely candidate.

DraconicAcid - 19-10-2016 at 11:04

Fair enough.

Glacial acetic acid has a convenient melting point for such work, but it tends to supercool, and the liquid's a bit nasty. Cyclohexanol melts around room temperature, and could work.

Texium - 19-10-2016 at 19:12

Quote: Originally posted by DraconicAcid

Cyclohexanol melts around room temperature, and could work.

In theory it does, but it almost always contains a trace amount of water which depresses its melting point significantly.

DraconicAcid - 19-10-2016 at 19:59

Quote: Originally posted by zts16

Quote: Originally posted by DraconicAcid

Cyclohexanol melts around room temperature, and could work.

In theory it does, but it almost always contains a trace amount of water which depresses its melting point significantly.

I haven't had that problem- in our lab, we add about 2% cyclohexanone to the damned stuff so that it doesn't keep freezing on us.

j_sum1 - 19-10-2016 at 20:31

I did it with tert butanol. We got a nice sudden flattening of the cooling curve but did not get a noticeable restart of the curve after it had all solidified. Next time I will use a colder ice bath. But also the thermal conductivity and heat transfer is going to be different for a solid.

I would love to do this with sodium but cannot think of a good way of doing it. Gallium will shatter glass. Maybe lead or a solder? I am intuitively guessing that metals will show the property a bit better. Anyway, it did work but there is room for improvement.

DraconicAcid - 20-10-2016 at 10:02

Quote: Originally posted by j_sum1

Maybe lead or a solder? I am intuitively guessing that metals will show the property a bit better. Anyway, it did work but there is room for improvement.

The trouble with a solder or other mixture is that you'd have to use the eutectic to get a sharp melting point rather than a range.

Palladium vs. NaOH

ElizabethGreene - 20-10-2016 at 11:40

Will a hot (75C) solution of NaOH and water attack Palladium?

Related question, how did you find this answer?

Thanks.

Texium - 20-10-2016 at 12:46

I would think not. The palladium would have to form some kind of oxoanion and there are no signs of palladium oxoanions existing.

Sulaiman - 21-10-2016 at 06:23

I have two oxygen concentrators, one I keep as backup for the one with my mother,
I occasionally use it for myself, and occasional for experimenting

one of these http://www.ebay.co.uk/itm/GENUINE-JYT-90-ADJUSTABLE-1-5L-OXY...
specified at 1 l/min. @ 90% O₂, 5 l/min. @ 40%.
they both work ... very good smouldering wood reaction.

Eventually the xeolite will loose efficiency and O₂ yield will drop.

Can someone suggest an EASY oxygen concentration test that I can perform with minimal diagnostic stuff to carry ?
Just to ensure that oxygen is being concentrated.

The O₂ is not for life support, just assistance, so non-critical, absolute measurement not required, just relative to new/now.

Separate question;
Out of curiosity I would like to know the absolute O₂ concentration of the machine that I have,
I have burettes, flasks etc. but nothing specifically for handling gases. I can burn Na, Mg etc.
but prefer not to if a less energetic method such as bubbling through a solution guaranteed to absorb or react with ALL of the O₂ can be done simply.
I can think of many possible methods but has anyone any practical advice ?

P.S. my mother has been using it for many hours per day almost daily for over nine months, so I can recommend this model ... so far.
(although less than £200 when I bought them)
It can extend your active smoking life well into the eighties

[Edited on 21-10-2016 by Sulaiman]

[Edited on 21-10-2016 by Sulaiman]

Metacelsus - 21-10-2016 at 08:57

See this paper, which uses oxidation of steel wool: http://pubs.acs.org/doi/abs/10.1021/ed1008798
It won't be very precise, but it seems easy.

Sulaiman - 21-10-2016 at 09:26

I have watched YouTube videos and looked at several web pages,
I only have one 2 ml and one 30 ml syringe in ground glass,
so iron, copper etc. in a heated tube between syringes would require new gas syringes.

I'm not too keen on rusting/corroding/burning stuff in a burette but it seems my most likely route,
I would of course compensate for the volume of 'fuel'+support
and measure at ambient pressure in the burette ... not partial vacuum like most demonstrations

I'd like something simple and reliable.
(I have methylene blue to detect oxygen, Thunberg tubes etc. if that helps with suggestions)

[Edited on 21-10-2016 by Sulaiman]

Cryolite. - 31-10-2016 at 18:40

I have some guanidine carbonate, but I would like to convert it to (dry) guanidine hydrochloride, for reactions involving freebase guanidine in alcohols. Although guanidinium cations of strong acids should be stable in boiling water, I am worried that the extreme heat needed to dry the hygroscopic guanidium salt would degrade it to ammonium chloride and urea. Is this concern misguided?

Unknown purple solution

bolbol - 12-11-2016 at 11:32

Today I was able to get a purple colored solution after mixing two different solutions.

I had this chunk of white solid(Either sodium salicylate or salicylic acid) from the a long time ago when I extracted aspirin from pills by acidifying the solution and basifying it back and forth. I am not sure what I ended up with but it was not soluble in water. I tried dissolving it but wouldnt work so I added some isopropyl alcohol to it to see if it helped. I saw a decrease in the amount of crystals on the bottom of the beaker but it didnt fully dissolve..

At the same time I had a beaker on the hotplate that pretty much limestone dissolving in HCl. Most of the HCl was consumed so I was heating it up to dissolve the last bit of the solid limestone chunk in it. This solution contained mostly calcium with small amounts of magnesium and iron(III) with other trace elements. I decided to pour some of this into my beaker with the alcohol and water mixture and it turned dark purple as if it was suddenly a permanganate solution.
Any ideas as to what the hell this could be? I don't know of any substance that has the same color as permanganates. Any insight would be appreciated.

UC235 - 12-11-2016 at 11:42

Fe+3 ions from your limestone solution form purple (or other colors depending on the nature of the phenol) complexes with phenols (which salicylates are).

Texium - 12-11-2016 at 11:50

Yep, that is most definitely the iron(III) salicylate complex. It works very well as a qualitative test since the color is so rich.

bolbol - 12-11-2016 at 12:46

Oh thats interesting especially for me as I have no background in organic chem. Thanks!

Iron screw electrolysis

ficolas - 14-11-2016 at 05:35

I wanted to make some iron oxide, so I electrolysed some rusted screw, however the solution turned a color I did not expect it to, so Im worried the screws could contain chromium.
http://i.imgur.com/CNaUKG5.jpg
The screws were alredy rusted when I used them, so I didnt think they could be stainless steel.
The colors make some sense to me, however is now what I remeber from doing it another time. I just want to make sure because I really dont want this to have carcinogenic compounds.

[Edited on 14-11-2016 by ficolas]

Why so many acids yet few bases

Sulaiman - 19-11-2016 at 01:29

When searching for chemicals I find a plethora of acids but very few bases - why ?

j_sum1 - 19-11-2016 at 02:55

Leaving aside the notion that every acid has its conjugate base...
I think it comes down to nomenclature as much as anything else. By which I mean that anything with a -COOH group gets (logically) designated as acid, compounds with a -NH2 group are called amines even though they act as bases (generally).

I'll let some else speak for the inorganic side of things.

awlb2 - 21-11-2016 at 13:05

Hello, I would like to know if phosphoric acid or sodium bisulfate is a suitable catalyst for esterification of short chain alcohols(e.g. ethanol) and aromatic carboxylic acids (e.g. benzoic acid)- I know esterifications occur 'slowly' using this catalyst but how much slower compared to a strong acid such as H₂SO₄ or p-TsOH, is it still feasible ? Does anyone know what pKa is approximately needed to deprotonate the carboxylic acid- does it simply have to be lower than that of the carboxylic acid's pKa. As sulphuric acid is not available for me(chemophobic parents) I am looking for other strong, less corrosive, acid catalysts.

Thank you in advance if you are able to help!

[Edited on 21-11-2016 by awlb2]

Metacelsus - 21-11-2016 at 13:38

Phosphoric acid should be a suitable substitute for sulfuric.

awlb2 - 21-11-2016 at 14:34

Thank you very much for replying Metacelsus- I will try it with phosphoric acid.

awlb2 - 21-11-2016 at 15:41

But what about sodium bisulfate? I believe it reacts with ethanol to form sodium ethyl sulfate- could this then react with the carboxylic acid to form the ester or would it react with more ethanol to form diethyl ether?

Gringard Question

Meltonium - 22-11-2016 at 19:17

I've always seen gringard reactions done with using bromine as the halogen with the magnesium. Can the reagent be prepared using chlorine or iodine? Are there significant drawbacks to using something other than bromine?

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