Chyros' chemistry thread
Chyros 24 Sep 2010
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 .
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 . The vid is of course made in a very amateuristic way (so shut up Wiz ) but it should serve its purpose well enough.
Also, another thing to kick off: a chemical problem I'll make up for you guys.
Don't quote something from the internet . You're free to (try and) look it up, but try to understand it as well, and post it in your own words .
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 .
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 . The vid is of course made in a very amateuristic way (so shut up Wiz ) 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.
Libains 24 Sep 2010
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.
TheDR 24 Sep 2010
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
Glad to see this thread has been created, i look forward to reading it regularly
Chyros 24 Sep 2010
@ AJ: correct . Now let's get deeper into this.
OK, so why does this electron jump back and forth? What causes it? And why the 4d and 5s orbitals specifically?
This is true for every metal, not just silver, by the way . 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.
AJ, 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.
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.
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.
Destiny 24 Sep 2010
Chyristry thread is finally done, eh, eh? 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 Pretty cool, a bit shaky but it's lovely to get an insight of The Life of a Chyros.
Hehehe, I thought you were going to give someone that flask of liquid nitrogen as coffee since it was so misty Pretty cool, a bit shaky but it's lovely to get an insight of The Life of a Chyros.
Chyros 24 Sep 2010
Destiny, on 24 Sep 2010, 17:10, said:
You sound quite...mature
Quote
a bit shaky
NergiZed 24 Sep 2010
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.
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.
Chyros 24 Sep 2010
I wouldn't be allowed to film what EXACTLY I'm doing either, since that is under copyright management . 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 .
Chyros 25 Sep 2010
Generalcamo 25 Sep 2010
BeefJeRKy 25 Sep 2010
Haha awesome thread Chyros. I should do this in my Bio and Electronics labs this semester
Chyros 25 Sep 2010
BeefJeRKy 26 Sep 2010
Rai 27 Sep 2010
scope, on 26 Sep 2010, 20:45, said:
Indeed. +1.
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.
Chyros 27 Sep 2010
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 .
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:
Try to guess what each compound is, and explain what causes the speckled effect . 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.
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:
Try to guess what each compound is, and explain what causes the speckled effect . 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.
Wizard 27 Sep 2010
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
Mbob61 28 Sep 2010
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
Edited by Mbob61, 28 September 2010 - 02:57.
For the second one, my brain seems to think Copper sulphate was blue? MY chemistry lessons seem like a long time ago now.
Mike
Edited by Mbob61, 28 September 2010 - 02:57.
Chyros 28 Sep 2010
Mbob61, 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
For the second one, my brain seems to think Copper sulphate was blue? MY chemistry lessons seem like a long time ago now.
Mike
Rai, on 28 Sep 2010, 5:26, said:
I think one of the yellowish colors is sulfur!
BeefJeRKy 28 Sep 2010
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?
Is the black precipitate Iron Sulfide? Is the first one Methyl Red?