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Chyros' chemistry thread


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#1 Chyros

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Posted 24 September 2010 - 12:12

I've been told to make a chem thread a million times, and now it's time. Ladies and gentlemen, I present you the Chyrochemistry thread.

This is where I'll post some chemistry-related stuff, mostly stuff I do in the lab. Not explosions or chemical warfare (unfortunately), but things that being in a lab are all about. It's mostly a notepad where I just sometimes post stuff like standard lab practices, basically to give you guys some idea of what organic chemistry is about. So every now and then I'll post a picture of some weird stuff (like that rainbow-coloured compound I showed in LPTPW once), or even a video from time to time. I'll also post a chemistry-related question sometimes for those who are interested.

This thread will probably be more monologue than dialogue, but still, feel free to ask chem stuff, make comments, or whatever.

To kick off things, I'll post a vid I recorded today of me tapping liquid nitrogen.

Tapping liquid nitrogen is the first thing a synthetic organic chemist does when he gets to the lab - after putting on his safety glasses and lab coat, that is. We use a system called a "Schlenk line" to provide us with easy access to nitrogen gas outflow and vacuum - it consists of two glass tubes with six three-way taps. The tubes are connected to a nitrogen blower and a vacuum pump, respectively. Vacuum is useful for removing (reactive) air from reaction vessels - you can use the nitrogen flow to replace this with (inert) nitrogen gas, or to evaporate off solvents. Liquids boil more easily under lower pressures, so evacuating something is a quick, easy and convenient way to get rid of solvents. The vacuum pump we use is an oil pump though, and to spare the pump, we trap the gaseous solvents in what is known as a "cold trap" before it reaches the pump, spoils the oil and over time, breaks down the pump's parts. To condense the gaseous solvents in the cold trap, which is essentially a long glass tube, we use liquid nitrogen which is roughly -196 degrees Celsius, i.e. quite cold. The cold trap is submerged in a dewar flask (an insulating metal container), which keeps the nitrogen cool for a long time. This makes sure the gases never reach the actual pump, as the cold trap is put in front of the pump in the vacuum circuit.

When submerging the cold trap in the nitrogen, you need to make sure that the vacuum line cannot pull in air from the outside, i.e. there shouldn't be any leaks or any taps open. If this is the case, the reduced pressure that the cold creates will suck in air, which is cooled into liquid air immediately by the liquid nitrogen. Over time, this will fill up your trap. Worse, if the leak is quite small, it will condense only liquid oxygen, which is a very nice sky blue colour. Unfortunately, liquid oxygen is very dangerous: it is used as rocket fuel, since it is a very powerful oxidant. Evaporating off organic solvents, which almost always are both volatile and highly flammable, will then set off a big explosion and cause a fragmentation bomb of glass to go off in your fumehood. Needless to say, this is to be avoided :Ban: .

NB: my voice sounds rather weird here - I was kind of whispering through clenched jaws, so that's what's making me sound so strange if you're wondering :P . The vid is of course made in a very amateuristic way (so shut up Wiz :P) but it should serve its purpose well enough.



Also, another thing to kick off: a chemical problem I'll make up for you guys.

chemical problem 1 said:

Most metals have roughly the same steely metallic colour that we know well. Gold is one of the very few which don't have this colour. Explain what causes gold to have this different colour.
Don't quote something from the internet :P . You're free to (try and) look it up, but try to understand it as well, and post it in your own words :P .
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#2 Libains

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Posted 24 September 2010 - 12:34

Gold's gold due to the number of electrons suspended in orbitals around the nucleus - because of the number of electrons, they jump quickly between the 4d and the 5s orbitals. This results in contraction between those two orbitals, which changes the light absorbtion properties of the gold atom. It absorbs light in the visible spectrum, specifically blue light. The combination of the rest of the reflected colours results in the golden colour. Note silver has similar properties, but the decrease in density of electrons means that it does not quite absorb in the visible spectrum - therefore it has every colour, resulting in a silvery/white sheen.
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#3 TheDR

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Posted 24 September 2010 - 12:36

It's the science lesson thread (and we even get homework D:!).

Glad to see this thread has been created, i look forward to reading it regularly :Ban:
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#4 Chyros

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Posted 24 September 2010 - 12:41

@ AJ: correct :Ban: . Now let's get deeper into this.

View PostAJ, on 24 Sep 2010, 14:34, said:

Gold's gold due to the number of electrons suspended in orbitals around the nucleus - because of the number of electrons, they jump quickly between the 4d and the 5s orbitals.
OK, so why does this electron jump back and forth? What causes it? And why the 4d and 5s orbitals specifically?

Quote

Note silver has similar properties, but the decrease in density of electrons means that it does not quite absorb in the visible spectrum - therefore it has every colour, resulting in a silvery/white sheen.
This is true for every metal, not just silver, by the way :P . The only metals which are not the "standard colour" are gold, copper and osmium (which is very slightly blue).

EDIT: also, small thing I overlooked, it's not 4d and 5s, but 5d and 6s. Why won't the 4d and 5s electrons do this for gold?

Edited by Chyros, 24 September 2010 - 13:03.

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#5 Destiny

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Posted 24 September 2010 - 15:10

Chyristry thread is finally done, eh, eh? :P You sound quite...mature, I thought you'd have a more lighter-toned voice...but...






Hehehe, I thought you were going to give someone that flask of liquid nitrogen as coffee since it was so misty :Ban: Pretty cool, a bit shaky but it's lovely to get an insight of The Life of a Chyros.
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#6 Chyros

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Posted 24 September 2010 - 15:56

View PostDestiny, on 24 Sep 2010, 17:10, said:

You sound quite...mature
Yeah, I get that a lot :Ban: .

Quote

a bit shaky
Yes, apologies for that: I'm filming all of this with my mobile phone, so the quality isn't the best ever and it can get quite shaky (or even venture off what I want to show while I'm busy - I try to keep this to a minimum), but it should suffice. It gets especially fiddly when I have to change hands to do stuff, or even require both hands at the same time D: .
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Our Master has no need of money. But still he sits and counts it. As a meditation.
-The Book of Cataclysm


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#7 NergiZed

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Posted 24 September 2010 - 16:22

Cool, this stuff is relevant to my interests.

I don't think I'd be allowed (or have time to) film anything I do in the lab. Plus what I do is probably very boring and simplistic compared to you; currently I;m taking P-chem and instrumental analysis.

#8 Chyros

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Posted 24 September 2010 - 17:11

I wouldn't be allowed to film what EXACTLY I'm doing either, since that is under copyright management :Ban: . But stuff like this is basic for any lab chemist so it wouldn't hurt anyone of course. And P-chem isn't much to show on film about, yeah :P .
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Our Master has no need of money. But still he sits and counts it. As a meditation.
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#9 Generalcamo

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Posted 25 September 2010 - 04:25

YOU SHOULDN'T BE ALLOWED NEAR A CHEMISTRY SET

Spoiler


Nice stuff
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#10 Chyros

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Posted 25 September 2010 - 09:36

View PostGeneralcamo, on 25 Sep 2010, 6:25, said:

YOU SHOULDN'T BE ALLOWED NEAR A CHEMISTRY SET

Spoiler


Nice stuff
Fun fact: the stuff under your sink is considerably more dangerous than any chemistry set will ever be :Ban: .
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Our Master has no need of money. But still he sits and counts it. As a meditation.
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#11 Destiny

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Posted 25 September 2010 - 10:30

Pots, pans, a duster...
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#12 Generalcamo

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Posted 25 September 2010 - 22:05

View PostChyros, on 25 Sep 2010, 5:36, said:

View PostGeneralcamo, on 25 Sep 2010, 6:25, said:

YOU SHOULDN'T BE ALLOWED NEAR A CHEMISTRY SET
Fun fact: the stuff under your sink is considerably more dangerous than any chemistry set will ever be :Ban: .

Oh really? Is the answer Viniger and Baking soda?
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#13 BeefJeRKy

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Posted 25 September 2010 - 22:46

Haha awesome thread Chyros. I should do this in my Bio and Electronics labs this semester :Ban:
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#14 Chyros

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Posted 25 September 2010 - 23:42

View PostGeneralcamo, on 26 Sep 2010, 0:05, said:

View PostChyros, on 25 Sep 2010, 5:36, said:

View PostGeneralcamo, on 25 Sep 2010, 6:25, said:

YOU SHOULDN'T BE ALLOWED NEAR A CHEMISTRY SET
Fun fact: the stuff under your sink is considerably more dangerous than any chemistry set will ever be 8| .

Oh really? Is the answer Viniger and Baking soda?
That just fizzes a bit :lol: . If you intend to, it's easy to make bombs or gas grenades with some household cleaning stuff.


View Postscope, on 26 Sep 2010, 0:46, said:

Haha awesome thread Chyros. I should do this in my Bio and Electronics labs this semester :xD:
Do it mofo 8| .
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Our Master has no need of money. But still he sits and counts it. As a meditation.
-The Book of Cataclysm


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#15 deltaepsilon

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Posted 26 September 2010 - 01:02

Your voice is sexy :lol:
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#16 BeefJeRKy

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Posted 26 September 2010 - 12:45

View Postdeltaepsilon, on 26 Sep 2010, 4:02, said:

Your voice is sexy :xD:

I agree. It is epic for narration. The Discovery Channel should hire you for one of their shows :lol:
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#17 Rai

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Posted 27 September 2010 - 13:05

View Postscope, on 26 Sep 2010, 20:45, said:

View Postdeltaepsilon, on 26 Sep 2010, 4:02, said:

Your voice is sexy 8|

I agree. It is epic for narration. The Discovery Channel should hire you for one of their shows :lol:

Indeed. +1.:xD:

In other news, watching you do these kind of experiments want me to re-live my childhood hobbies in my spare time, although it's quite more random and not studied, like combining mixing foot powder, ethyl alcohol, coffee and water. D:
And I'll be watching this thread from every update you do. It's just that interesting.

Edited by Rai, 27 September 2010 - 13:06.

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#18 Chyros

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Posted 27 September 2010 - 17:43

Once I posted a picture of a bunch of coloured solutions I made, in LPTPW, now another Guess That Compound question, this time with a bunch of solids. Use the colour and texture of the compounds to figure out what they are. You are allowed to use any means at your disposal, though of course a chemical background will help :lol: .

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I had to use a flash to capture the colours in the most neutral way I could. The sixth one is pinkish red, and the fifth one is ochre speckled with green. To make the last thing a bit clearer, since the speckled effect is hard to capture with a compound overturned so much, here is a separate picture of the fifth compound:

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Try to guess what each compound is, and explain what causes the speckled effect :xD: . Good luck!

EDIT: I'll give a hint, too. All compounds except the red one are metal salts.

Edited by Chyros, 27 September 2010 - 17:52.

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#19 Destiny

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Posted 27 September 2010 - 18:11

Say cheese!
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#20 Chyros

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Posted 27 September 2010 - 18:31

View PostDestiny, on 27 Sep 2010, 20:11, said:

Say cheese!
:)
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Our Master has no need of money. But still he sits and counts it. As a meditation.
-The Book of Cataclysm


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#21 Wizard

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Posted 27 September 2010 - 22:22

I don't know what that fifth one is called in chemistry terms, but I am sure it was in my fridge whilst at uni :)

#22 Mbob61

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Posted 28 September 2010 - 02:56

I will have to dig out some of my old chem books (although i'm not sure i even took them to uni) if you want some answers from me :)

For the second one, my brain seems to think Copper sulphate was blue? MY chemistry lessons seem like a long time ago now.

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Edited by Mbob61, 28 September 2010 - 02:57.

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#23 Rai

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Posted 28 September 2010 - 03:26

I think one of the yellowish colors is sulfur!
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#24 Chyros

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Posted 28 September 2010 - 06:09

View PostMbob61, on 28 Sep 2010, 4:56, said:

I will have to dig out some of my old chem books (although i'm not sure i even took them to uni) if you want some answers from me :)

For the second one, my brain seems to think Copper sulphate was blue? MY chemistry lessons seem like a long time ago now.

Mike
Heh, yeah, do try :D . Copper sulphate is indeed blue, but a lighter blue than this compound, which is more of a dark cyan. You're quite close though ;) .


View PostRai, on 28 Sep 2010, 5:26, said:

I think one of the yellowish colors is sulfur!
Good guess, but no cigar - sulphur is very yellow, but these compounds are orange and a kind of ochre, and sulphur isn't a metal salt ;) .
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#25 BeefJeRKy

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Posted 28 September 2010 - 13:23

If the blue one isn't copper sulfate, it's probably hydrated Copper Nitrate (anhydrous form is white)

Is the black precipitate Iron Sulfide? Is the first one Methyl Red?
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