Sciencemadness Discussion Board - Lab Fridge. I searched around and Didn't Find Much...

what does ether do when it comes in contact with fats ?

could that reaction be of any synthetic importance(to make protecting groups?)

Usually the phase is liquid and it extracts fats, but since Magpie is talking vapors here, he does literarily mean it tainted, or contaminated his food. It is possible to use ethers as protecting groups for alcohols, or even special ether-like ketal/acetal groups on ketone and aldehyde respectively... but this is the formation of an ether, not the use of one.

Ether lipids (of glycerol) are biological signaling and structural molecules, and the synthesis of them would require etherification of specific glyceride chains, so that could be viewed as a use in the synthesis of these compounds, in some manner of thinking.

CuReUS - 7-10-2014 at 23:53

You can use a normal fridge for the storage of most non-flammable chemicals without any issues. And storing highly sensitive explosives like diazomethane is probably a less than good idea regardless of what type of fridge you own.

but because of its explosive nature,no one will ship it to you(it might blow up during transportation

) ,and synthesizing it is a pain(you need to use a special distillation kit from Sigma-aldrich because diazomethane can explode if you use normal ground glass joints

so chemists make it in big batches once and for all and store it in the frigde

and you cant deny the fact that it is the best alkylating agent around

Quote:

If you want to store flammables safely, then you can still use a normal fridge, with some limitations. You need to make sure that there are no ignition sources inside the fridge. That means, remove the light socket, any thermostats which switch internally, and so forth. These things can be removed from a regular fridge or replaced with external equivalents, if you know what you're doing (or know someone who does!).

in today's fridge,the defrosting is automatic,which means the compressor "switches" on and off every 12 hours.now you cant take the compressor out,can you

so you would have to buy a fridge with manual defrost,and every time you defrost it,you have to take out all the chemicals.finding such a fridge with and age old technology in today's world can be challenging :cool:

Quote:

The cooling coils are usually made of aluminium these days.... I suspect that you could coat them with epoxy or something resistant, but I don't know how well that would work.

the coils act as a heat sink.what that means is that the coolant absorbs heat from whatever you store in the fridge,dumps it into the heat sink and in the process becomes cooler so that it can absorb heat again and the cycle can be repeated.the heat sink in turn dumps it into the atmosphere and it has to do that fast,or you might just wait for winter to keep things cool

.hence a good conductor like aluminium,before they used copper but copper is expensive and will increase the weight of the fridge(copper is more dense that aluminum,thats why overhead cables and high tension wires are made of aluminum

covering it with epoxy will decrease its ability to lose the heat to the atmosphere
but wont the aluminum be already covered with an oxide layer,and isnt that oxide layer resistant to even conc nitric acid(thats why nitric acid is transported in aluminum tanks)

[Edited on 8-10-2014 by CuReUS]

CuReUS - 7-10-2014 at 23:59

Quote: Originally posted by Chemosynthesis

what does ether do when it comes in contact with fats ?

could that reaction be of any synthetic importance(to make protecting groups?)

Usually the phase is liquid and it extracts fats, but since Magpie is talking vapors here, he does literarily mean it tainted, or contaminated his food..

so does that mean that magpie kept the ether in the fridge one night and the next morning he saw that all the fatty foods had become emulsions?

Little_Ghost_again - 8-10-2014 at 00:04

Just use peltier cells! double them up for better performance, you can get them really cheap on ebay. My little polystyrene fridge box with 6 cells is around 1c most the time, all you need is a difference in temperature.

Chemosynthesis - 8-10-2014 at 00:05

so does that mean that magpie kept the ether in the fridge one night and the next morning he saw that all the fatty foods had become emulsions?

Probably more comforting and interesting than the unpalatable surprise I suspect he had.

[Edited on 8-10-2014 by Chemosynthesis]

CuReUS - 8-10-2014 at 00:21

Just use peltier cells! double them up for better performance, you can get them really cheap on ebay. My little polystyrene fridge box with 6 cells is around 1c most the time, all you need is a difference in temperature.

i thought that a difference in temperature would produce an electric current according to the seebeck effect

to do the opposite i.e the peltier effect ,you would have to pass current through it .which will make one junction(or one side as in the peltier cell) hot and the other junction cold

generally peltier cells are used in biolight camping stoves

in these stoves ,one side is exposed to the heat from the fire whereas the other side is exposed to the atmosphere(in this case the cool night air

) .this will produce a current which can be used to charge your phone etc

but is this an efficient solution .the size of the fridge will be really small(i have heard they make portable frigdes with this idea)

Little_Ghost_again - 8-10-2014 at 12:05

Yes your correct, however if you put the hot side inside the fridge and the cold side of that outside the fridge and backing onto the hot side of the other, then you put a cpu aluminium heatsink on that, wire a 35mA (or less) cpu fan (you can find them at the dump but dont use ones over about 35mA.
Then what happens is the cell pulls hot air from inside the fridge to the outside, this produces a current as you say, but if you have them back to back and a temp difference then normally you can get the fridgee pretty cold if you use the wrong side in the fridge, sometimes the fan will cycle alot but that dosnt matter. what matters more is you draw off and use the current hence the heatsink and fan.
Works a treat, I also use this sort of thing on my fishtank LED lights, it keeps them cool and powers the fan.
It dosnt work if you put the cold side in the fridge though, in you do that then you need to power it, you also cant (I dont think anyway) get below about 1C

[Edited on 8-10-2014 by Little_Ghost_again]

aga - 8-10-2014 at 12:47

The Peltier effect, simply put, is that if you pass a current through a Peltier device, the Heat transfers from one side to another.

Often referred to as a 'Peltier Heat Pump', as it basically pumps the heat from one side to the other.

They are really Cool devices.
Oh, and Hot too, on the other side.

Little_Ghost_again - 8-10-2014 at 13:19

Quote: Originally posted by aga

The Peltier effect, simply put, is that if you pass a current through a Peltier device, the Heat transfers from one side to another.

Often referred to as a 'Peltier Heat Pump', as it basically pumps the heat from one side to the other.

They are really Cool devices.
Oh, and Hot too, on the other side.

You dont have to pass a current though, if you use them back to front then they make a current. place your hand on the cold side and you can light a led, use a linear technology dooh dah and you can up the voltage output and power a fair bit.
Weurth elektronica do a cool kit for energy harvesting, we have one at school

zenosx - 8-10-2014 at 16:04

I don't "Need" to store ether in the fridge as my lab stays pretty well at 20C, I was thinking more of lowering vapor pressure n such, i suppose it isn't really necessary. Having one just for chemicals would be ideal as I will not mix chemistry and cooking

On the manual defrost, my current (old) mini fridge upstairs is exactly like that. I have to unplug and defrost it manually. Maybe I'll use it and buy a new one for the upstairs.

Thanks for all of the very helpful replies. I learned quite a bit that I didn't know.

Oscilllator - 8-10-2014 at 20:49

Little_Ghost you seem to be implying that your fridge requires no power source, which I find impossible to believe given those pesky laws of thermodynamics. Do you think you could post a diagram so we could better understand what you are talking about?

[Edited on 10-10-2014 by Polverone]

CuReUS - 9-10-2014 at 08:20

i think what he is trying to say is this
let one peltier cell be represented like this- [c||h] (actually the formation of cold and hot side depends on the direction of the current ,which depends on how you connect the terminals of the peltier cell with the terminal of a battery)

now suppose two cells are kept side by side ,the cold side of one cell inside the fridge,the hot side of the first cell facing the hot side of second cell and the cold side facing the fan

fridge -c||h-h||c -fan

now initially there is no hot or cold side
when the fan is switched on the two junctions are created in the right cell
due to this a currect flows in that
that current flows to the second cell and makes two junctions
but isnt it easier to just connect the peltier cell to the external power source
and wont the cpu fan cause sparks if the connections get corroded

Little_Ghost_again - 9-10-2014 at 10:50

No I didnt explain well.
In the weurth kit there is a cell connected to a circuit to boost the current etc so it runs a micro board and LCD.
The hot side of the cell is connected to heat sink of largeish size, the side that feels a bit cooler is the side you place your hand or whatever. Now this side drags the heat from your hand to the other side of the plates ~9they are just N and P type junction plates, this produces a current and the micro and LCD light up.
So I took this further, Iput the side that got warmer to another plate, this warmer side is sandwiched with the side that feels slightly cooler on this second plate, this drags the heat out quicker from the first cell. The heat sink now goes on the warm side of the second cell so it can rid itself of heat.
They work by temperature gradients so the warmer of the two sides must have a large ish heat sink. the more heat you can shed from the warm side the cooler the cold side gets.
its not magic just thermodynamics, or basically a heat pump!
The fan just helps use the current and give the cells two sides, they come with a red and black lead, although you can wire any way around stick to the red and black and dont put in serise.
To get it going properly you warm the side inside the fridge to create a temperature gradient.
It does eventualy equal out and stop making a current, but in use I havnt seen this.
With heat from say fish tank lights the cells will produce plenty of current as long as tere is heat.

Little_Ghost_again - 9-10-2014 at 10:53

Forgot to add that as long as the room the fridge is in is at least 8c warmer than inside the fridge it works fine, if your room is say 3c then it isnt going to work very well, if you heated the room to 60c you would get a freezer

Lambda-Eyde - 9-10-2014 at 12:49

>>> https://www.sciencemadness.org/whisper/viewthread.php?tid=20...

Little_Ghost_again - 9-10-2014 at 13:06

Ok one last try at this and will put basically.

There is no power required in the terms of electric, this isnt new or dosnt break any thermo laws, think solar................

How the cells themselves work is by using the same type of material found in a transistor, P and N type materials in a PNP or NPN transistor.
All that happens is electrons move from one side to the other in the presence of a temperature gradient.

So your power is there in the form of electrons, they move from N to P (actually it might be the other way I cant remember at the mo), anyway they move from one side to the other. as they move they take latent energy (heat) with them.
So in doing this they can produce power, solar uses light to do this, peltier cells can do it using heat.
Most people actualy apply a current to the cell to make them heat one side or cool the other, but you can do it by heat and a difference in tempreture and create a current.

watch this for a better explanation, my fridge just uses two cells back to back and linear technology chip to manage the harvesting and bump the power up with joule thief like circuit

https://www.youtube.com/watch?v=9aSPopIcKLQ

Oscilllator - 9-10-2014 at 17:47

The way I understand your device, you have a temperature difference between the outside and inside of the fridge. You use this temperature difference to generate electricity, which you then use to power another peltier cell and create an even greater temperature difference. This is analogous to using a motor to run a generator that powers itself, and is impossible.
The problem is your device has no power input; it just runs by itself. Solar cells have a power input of sunlight. If you remove the sunlight, the power stops. Peltier cells have a power source of heat. Remove the heat source, the power stops. This is the key difference here that makes your device impossible.

The specific law of thermodynamics you appear to have violated is the second one. You have gone from a homogenous system with a uniform temperature, and created a temperature difference. This is impossible UNLESS you input some kind of energy in the form of light, electricity or heat.

With regards to the power source being electrons, they are not. Electrons can convey power, but they are not a source in and of themselves. In the same way when I throw a ball across the room and hit somebody, I have transferred energy to them but the source of the energy is not the ball, it's me.

ziqquratu - 9-10-2014 at 22:26

Regarding diazomethane:

but because of its explosive nature,no one will ship it to you(it might blow up during transportation

) ,and synthesizing it is a pain(you need to use a special distillation kit from Sigma-aldrich because diazomethane can explode if you use normal ground glass joints

so chemists make it in big batches once and for all and store it in the frigde

and you cant deny the fact that it is the best alkylating agent around

"Best" in terms of reactivity - maybe. But "best", factoring in convenience and safety? Hmmm... Besides, you can easily use regular, cheap glassware to generate diazomethane as required - just not stuff with ground joints. Diazomethane WAS prepared - safely! - before Aldrich started selling kits, you know! Not relevant to this thread, though, and I think I've posted the procedure we used to use on the forum in the past anyway, if you're interested.

in today's fridge,the defrosting is automatic,which means the compressor "switches" on and off every 12 hours.now you cant take the compressor out,can you

The compressor of every fridge I've ever seen IS on the outside - otherwise it'd be trying to cool itself as well as the other contents of the fridge! Trust me, a regular fridge can be made flammable safe - been there, done that. It's only things inside the actual refrigerated compartment that need to be sparkless - in most cases, the light and the thermostat are the only things that need moving outside.

Yes, it certainly would decrease heat transfer - but by how much? Given a lab fridge is opened only rarely, meaning heat loss is less of an issue, would it matter? This I don't know the answer to.

but wont the aluminum be already covered with an oxide layer,and isnt that oxide layer resistant to even conc nitric acid(thats why nitric acid is transported in aluminum tanks)

Aluminium oxide is perfectly happy to react with (most?) mineral acids, just like aluminium itself.

The specific law of thermodynamics you appear to have violated is the second one.

Yeah, everyone wants to get around that one...

[Edited on 10-10-2014 by ziqquratu]

Little_Ghost_again - 10-10-2014 at 01:41

The way I understand your device, you have a temperature difference between the outside and inside of the fridge. You use this temperature difference to generate electricity, which you then use to power another peltier cell and create an even greater temperature difference. This is analogous to using a motor to run a generator that powers itself, and is impossible.
The problem is your device has no power input; it just runs by itself. Solar cells have a power input of sunlight. If you remove the sunlight, the power stops. Peltier cells have a power source of heat. Remove the heat source, the power stops. This is the key difference here that makes your device impossible.

The specific law of thermodynamics you appear to have violated is the second one. You have gone from a homogenous system with a uniform temperature, and created a temperature difference. This is impossible UNLESS you input some kind of energy in the form of light, electricity or heat.

With regards to the power source being electrons, they are not. Electrons can convey power, but they are not a source in and of themselves. In the same way when I throw a ball across the room and hit somebody, I have transferred energy to them but the source of the energy is not the ball, it's me.

NO NO NO NO
I DO NOT power the cells at all! I use the power produced by both cells to simply drive a jouel thief type circuit that goes to a fan, the fan just helps get rid of the heat on the last cell in the stack, it simply makes it a little more efficient.
The more heat you draw away from the hotist plate the colder the coldest plate get.
Look at the video link its a legit electronics blog.
No magic or thermo laws broken.
You dont power any of the cells in fact you have to use the power they produce to keep the electrons flowing.
Search you tube and look for the weurth elektronica energy harvesting kit, or the linear technology stuff, search with key word TEG or thermo electric generator.
The idea is to generate small amounts of current with heat difference, use that current to light a led or run a small fan it dosnt matter, but using the power keeps the electrons flowing therfore one plate gets warm and one gets cold.
I cant believe you make this seem so hard!!

Tell you what I will got get the links, these are major companies and well known in electronic circles

Little_Ghost_again - 10-10-2014 at 01:46

Right this kind of explains it
https://www.youtube.com/watch?v=YhynSkFlJOs
the side he heats you put in the fridge, the side he dosnt heat you add a large heat sunk too, simples. the side he is heating will take ANY heat from 1C up and pass it to the other side, as long as you use a heat sink to get rid of this heat it will keep going, you use the current produced so the electrons are used up and keep flowing, I just added another cell on top to make the whole thing a bit more efficient.

Little_Ghost_again - 10-10-2014 at 01:51

GRRR if I get £6 soon I will buy a couple more to show you, when you buy them and leave them in a room for a day unconnected to anything, you find one side hotter than room temp and one side cooler than room temp, they never equal room temperature on the plates. its this principle I use to cool a box

Oscilllator - 12-10-2014 at 03:48

Little_Ghost I understand perfectly how these cells work, that's not the problem. The problem is that as you keep saying:

I DO NOT power the cells at all!

If you leave the cell in a room alone by itself I firmly believe that you will not find one side to be hotter or colder than the other. To create a temperature difference, you must apply an an electric current, it's as simple as that. I think it would help if another member could weigh in on this here, as it really is quite elementary.
I have just bought 4 "peltier thermoelectric coolers" from ebay for a total of $9.92 since this debate has sparked my interest in these devices. When they arrive I will leave one alone in a room, and we shall see if a temperature difference develops!

unionised - 12-10-2014 at 04:34

I work for a lab that should really know better but a decade or so back we blew up a fridge.
It was used for storing urine samples after they had been extracted with ether - so they had ether in solution and perhaps a little of the liquid. They were "sealed" with plastic film.
The ether vapour diffused out through the film, mixed with the air and was ignited - most probably by the thermostat.

After that cockup we decided that all the fridges on site would be sparkproof- even the ones for the milk in the tea room.

In many cases we simply bought new, sparkproof, fridges but in some cases we got someone to alter them to make them sparkproof. All they needed to do was move the thermostat's switch outside the cold storage compartment of the fridge.

If I wanted a sparkproof fridge at home for storing chemicals, I'd use one of these sorts of things.
Brushless motor (and it's outside the "box" anyway to improve efficiency.

http://www.amazon.co.uk/Coolbox-Electric-Warm-Cool-Box/dp/B0...

Littleghost seems to have missed the bit in that video where they supply energy to the peltier with a blowtorch.

It's easy to prove that you can't have a fridge that runs without some sort of power.
Imagine that I could get one- let's say it keeps the inside at 4C while the outside is at 20 C

I can get some chloroethane and put it outside the fridge where it will boil.
(the boiling point is 12 C or there abouts. I can use the vapour it produces to run a small turbine and I can connect that turbine to a generator to make electricity.
Then I can take the vapour through a tube in the fridge and cool it so it condenses back to a liquid.
I can feed that liquid back into the boiler (outside the fridge) and have it circulate- with a bit of clever design, I can use gravity to make the dense liquid flow back into the boiler.

Great! free electricity.
But, we know that's impossible- due to the laws of thermodynamics.
So we know the fridge can't work

Little_Ghost_again - 12-10-2014 at 07:30

Little_Ghost I understand perfectly how these cells work, that's not the problem. The problem is that as you keep saying:

I DO NOT power the cells at all!

Make sure you have a decent heat sink on one side, as you say you need a temperature difference, put the heat sink on the warm side.
Seriously this isnt magic or breaking and laws of physics. It a simple move of electrons from a P type material to a N type material, as long as one side is at a different temperature it works, the greater the difference the better, but if you leave in a room with a heat sink on you will find one side slighly colder than the other.
They use them for wood burning stoves as well, they have a fan on a all metal stand with a cell on the bottom, it gets hot and drives the fan this blows warm air into the room.

Little_Ghost_again - 12-10-2014 at 07:33

Forgot to add google thermal electric generator and energy harvesting, look at link from linear technology and weurth elektronica, both huge and reliable companies.
They have loads of info on using TEGs.

unionised - 12-10-2014 at 10:02

What you are proposing is like connecting the shafts of a generator and a motor together and connecting the wires so the generator feeds the motor then hoping it will make electricity.

A wood burning stove provides energy to maintain the temperature gradient.

TEG work just fine, but you can't use one to power itself any more than you can pick yourself up by your bootlaces.

CuReUS - 13-10-2014 at 05:04

the only way to end this debate is this-
little ghost ,i have great respect for you as i have read your previous posts
please be a gentleman and post some picture of your setup or atleast upload a blueprint or something

SeReOUSLi -this discussion is going nowhere and this isnt even a physics forum :cool:

[Edited on 13-10-2014 by CuReUS]

Little_Ghost_again - 13-10-2014 at 05:17

the only way to end this debate is this-
little ghost ,i have great respect for you as i have read your previous posts
please be a gentleman and post some picture of your setup or atleast upload a blueprint or something

SeReOUSLi -this discussion is going nowhere and this isnt even a physics forum :cool:

[Edited on 13-10-2014 by CuReUS]

I am trying to sort pics out, I havnt posted pics for a little bit because the reader on the laptop isnt recognizing the camera card!!
But I totally agree with you, Ihave read all my posts in this thread and none of them put across what I am trying to say or describe! Its utterly frustrating for me and yes pictures will sort it out.
Trust me its gonna be a face palm moment when you see it and say "why didnt you just say X Y Z) (face palm for me).

The only other thing I can to add before I can get pics working again is the following.
It was mentioned in a post above that I didnt say about the guy using a blow torch.
Thats important because the point is he used a blow torch to get more power (obviously he put more energy in so more out).
The way the fridge thing works is really simple, take the blow torch thing, the idea isnt to produce electric energy, the idea is to make sure that any current however small is used (in the fan coil even if it isnt enough to move the fan).
If you were to put the outside of the cells against a radiator then the other side of the side gets cooler. In a way the current is a by product and not of much relevance to the fridge, except if you dont use it the whole thing reaches stale mate quicker.
Right I have reached the point if I continue it will confuse more, so maybe this will help sum it up.
Simple heat pump? thats the principle, no its not rapid cooling no it dosnt always make the fan spin (it does on my fish lights but they produce alot of heat therefore.
more energy).

I am anxious to get you pics as my explanation is utter crap, I am really sorry I cant express myself properly with this, to be honest its a utter shambles
LG

hyfalcon - 13-10-2014 at 05:20

This doesn't violate any thermodynamic law. He's using a heat source to stimulate the system, thus, energy in.

CuReUS - 13-10-2014 at 05:23

Quote:

I am trying to sort pics out, I havnt posted pics for a little bit because the reader on the laptop isnt recognizing the camera card!!

really ,i thought a tech savy person like you must have a camera with an USB cable atleast

also now you are telling that you keep the cells next to a radiator(oscillator,i hope you are reading this)

a picture speaks a thousand words

Little_Ghost_again - 13-10-2014 at 07:40

Quote:

I am trying to sort pics out, I havnt posted pics for a little bit because the reader on the laptop isnt recognizing the camera card!!

A tech savy person like me would have a camera with a cable,but a tech savey 14 year old kid dosnt have the money for a camera, so said kid borrows dads Nikon D7000 which while it did have a cable is somewhere I havnt a clue! its also not a standard cable, so tech savy kid stuck with taking sd out of camera when he can sneak said camera out of the draw!

NO
I said or hinted that putting it by a radiator makes it work better, i was trying to help described the principle!

I already said right at the start that the better the temp difference the better it works.
I have found the weurth kit as well so will take pic of that. The teg has a heat sink one side and the moment you take the board out the box one side is definitely colder than the other.

I dont get why you think it breaks thermo laws??? all it does is move heat from side to other, it does it better though if you use the electrons up as it does it.
I now cant for the life of me remember which side is which, but one is N type material and one doped P type, little electrons move from one to the other depending on a difference in tempreture, simples. No magic no broken rules, used a great deal for energy harvesting and powering micro controllers like energy micro Gecko's (one comes in the kit), you switch the jumpers put your hand on one side of the teg and the LCD comes alive and gives you the time or something.
LG

Little_Ghost_again - 15-10-2014 at 19:13

I have been lent one of the weurth energy harvesting kits!!! Hopefully I can get the camera sorted as it can video as well, that way apart from my own set up, you can see exactly what I been banging on about.
When I get it I will take it out the box leave 10 mins and take the temperature both sides (unconnected from the micro board).
There will be a temperature difference for sure as one side has a simple small heat sink, then on video I will place my hand on the side without the heat sink and connect the micro board, this should spring to life, but more importantly keep watching the thermometers, the side with the heat sink will warm up as the side with my hand tries to get rid of the heat.
And that is precisely how my fridge works.

Oscilllator - 15-10-2014 at 20:27

I look forward to the results of this experiment. I to will conduct many experiments when my peltier cells arrive.

To be clear, the energy harvesting part of the kit is just a peltier cell with a heat sink on one side, and it will develop a temperature difference on its own without you providing any power input?

Little_Ghost_again - 16-10-2014 at 05:52

I look forward to the results of this experiment. I to will conduct many experiments when my peltier cells arrive.

To be clear, the energy harvesting part of the kit is just a peltier cell with a heat sink on one side, and it will develop a temperature difference on its own without you providing any power input?

Right for clarity
http://www.we-online.com/web/en/electronic_components/produk...
This is the kit, inside is a few different ways to power the micro board, you choose which by way of jumpers on the harvesting board.

If you put the jumper to the TEG (peltier cell or whatever you want to call it) then you find the side with the heat sink on is warmer than the side without.
Wether or not the micro board springs to life depends on the amount of current, this depends on heat, so a warm room you are likely to get it to work a cold room unlikely, you need some heat in some form to produce power to reach a level that the harvesting board can power the micro board.

But that is not the point is it???
The point of the whole thing is to prove that with a heat sink and two cells back to back you get a much colder side and a warmer side.
In this instance because its only one cell I expect to see less cooling but still a couple of degrees difference between the hot side and cold side.
I cant remember which way round it goes but one side will try and take the heat via its plate and pass to the other side.
So as my house is around 15c I doubt its enough to power the board but all we need is one side colder than the other and point proved

Little_Ghost_again - 16-10-2014 at 05:53

Incase anyone wants one of the kits DONT!!! They are not worth the money! There is a better board now by linear tech and the rest of the stuff you can pick up cheap, I am borrowing this kit from a center I know.

zenosx - 19-10-2014 at 17:43

More importantly ,, who got to clean up all of the hot piss! LOL

Quote: Originally posted by unionised

I work for a lab that should really know better but a decade or so back we blew up a fridge.
It was used for storing urine samples after they had been extracted with ether - so they had ether in solution and perhaps a little of the liquid. They were "sealed" with plastic film.
The ether vapour diffused out through the film, mixed with the air and was ignited - most probably by the thermostat.

After that cockup we decided that all the fridges on site would be sparkproof- even the ones for the milk in the tea room.

In many cases we simply bought new, sparkproof, fridges but in some cases we got someone to alter them to make them sparkproof. All they needed to do was move the thermostat's switch outside the cold storage compartment of the fridge.

If I wanted a sparkproof fridge at home for storing chemicals, I'd use one of these sorts of things.
Brushless motor (and it's outside the "box" anyway to improve efficiency.

http://www.amazon.co.uk/Coolbox-Electric-Warm-Cool-Box/dp/B0...

Littleghost seems to have missed the bit in that video where they supply energy to the peltier with a blowtorch.

It's easy to prove that you can't have a fridge that runs without some sort of power.
Imagine that I could get one- let's say it keeps the inside at 4C while the outside is at 20 C

I can get some chloroethane and put it outside the fridge where it will boil.
(the boiling point is 12 C or there abouts. I can use the vapour it produces to run a small turbine and I can connect that turbine to a generator to make electricity.
Then I can take the vapour through a tube in the fridge and cool it so it condenses back to a liquid.
I can feed that liquid back into the boiler (outside the fridge) and have it circulate- with a bit of clever design, I can use gravity to make the dense liquid flow back into the boiler.

Great! free electricity.
But, we know that's impossible- due to the laws of thermodynamics.
So we know the fridge can't work

[Edited on 20-10-2014 by zenosx]

zenosx - 19-10-2014 at 17:46

I also want to see the setup because I also see several violations here. Simply putting a peltier to a peltier will not generate the equivalent of perpetual motion as that violates all kinds of physical laws. Energy comes from somewhere, even if it's just temperature fluctuations in the room, however I can't see these being big enough to create enough current to power something like this... I suppose I am also confused....

Little_Ghost I understand perfectly how these cells work, that's not the problem. The problem is that as you keep saying:

I DO NOT power the cells at all!

unionised - 20-10-2014 at 13:30

Quote: Originally posted by zenosx

More importantly ,, who got to clean up all of the hot piss! LOL

Quote: Originally posted by unionised

[Edited on 20-10-2014 by zenosx]

Perhaps I should have mentioned that the explosion blew the door off the fridge and dug a hole in the wall opposite. If anyone had been in the way they would have been seriously injured or killed.
However the sample were probably largely unaffected by the incident.

CuReUS - 21-10-2014 at 03:21

Quote: Originally posted by unionised

the same thing happened with diazomethane,the door blew off and got embedded in the opposite wall 20 metres away

chemical coincidence dont you think
maybe its genetic ,who knows

DrMario - 26-10-2014 at 07:47

One thing to think about, however, is corrosives. The cooling coils are usually made of aluminium these days, and do not like even the tiniest traces of acid in the atmosphere. If the coils are exposed and you have corrosives in there, you will walk in one day and find the fridge running with no coolant (trust me, I speak from experience... one very well sealed bottle of thionyl chloride was enough to ruin the coils in a six month old, $1500 kitchen-type fridge we used in our university lab!). I suspect that you could coat them with epoxy or something resistant, but I don't know how well that would work. Of course, in a home lab, you may well not have any corrosives you want/need to store cold anyway.

I got myself a minifridge specifically to store corrosives: the big three (sulfuric, nitric and hydrochloric acid) along with some phosphoric acid and H2O2. While I could never smell anything noxious in the fridge so far, it's early days (only got it a week ago) and after I read your post I decided to place a piece of polished aluminium inside the fridge. I plan on checking it from time to time to see if there is any corrosive gas building up. Do you think this is a good idea?

ziqquratu - 26-10-2014 at 16:43

At the least, I can't see how it could hurt. The problem, as I see it, is if you can detect a problem before it breaks through the (relatively thin) evaporator tubing and all your refrigerant leaks out. One pin hole is all it takes...

All I can say is, if you want to be certain, the aluminium tubes which contain the coolant must never be exposed to the internal atmosphere of the fridge. In professional lab fridges, those tubes are completely outside the chamber, behind a plastic sheet (but obviously they're still inside the fridge's insulation!). My thought is that a layer of protective epoxy might also do the job to protect a regular fridge, but that's 100% untested conjecture on my part!

For the items you've listed, though, I'd only keep the H2O2 in the fridge; everything else is room temp storage! Also, of those, I'd think HCl would be the biggest risk to your fridge - it's highly volatile and loves aluminium (and I would expect HNO3 to be similarly problematic). Sulfuric and phosphoric, being largely non-volatile, I would expect to be less of an issue, but there's no real need for them to be in there anyway, as far as I can imagine.

DrMario - 26-10-2014 at 17:45

My need for storing the HCl in the fridge comes from a complete lack of a cool storage. I really don't need the fridge to be cold - I just need a place where the temperature will not be >30C during summer days.

Still, you gave me a lot to chew on, ziqquratu.

ziqquratu - 26-10-2014 at 22:51

Meh, working in university labs, we kept all our HCl (up to 37%) at room temperature. And "room temperature" varied between 0*C and 45*C (I'm in Australia, and our labs had terrible heating/cooling!). No problems were noticed for synthetic purposes!

DrMario - 27-10-2014 at 00:35

Okay. The thing is, I use very small amounts of the stuff, which I keep in a smaller bottle, while the larger bottles are stored away for the long haul. I imagine you would be opening your bottles regularly, which I don't intend to do.

ziqquratu - 27-10-2014 at 20:14

It would, of course, depend on the lab, and I'm not sure of your own experience, but you might be surprised by how little mineral acid a typical organic lab may use. Most of my work has, to date, required acids in the 1-5M range, with HCl being the most used. At a guess, I'd make up a litre of 5M HCl from the conc. acid say four times a year, and a litre of 1M perhaps once a month. I'd use sulfuric acid a couple of times a year, and the only use I recall having for nitric acid was preparing aqua regia for cleaning, maybe once a month or so. Use by other people in the lab was probably less than that (I work with lots of amines, so a lot of acid-base workups!). Just to demonstrate, in my previous lab with between six and ten chemists, there was a 2.5 L bottle of 70% nitric which was open when I got there and still had a good amount remaining when I left after over 6 years! I think in that time we used maybe 5L of sulfuric acid. We did go through a lot of HCl, though, but only on the order of a few (5-10) litres per year at most.

Furthermore, keeping the bottles closed up should, I imagine, mean they're even less likely to change concentration significantly! So long as you keep them under reasonable conditions (a nice cool corner with reasonable ventilation, out of the sun and whatever) I'd suspect they should be fine for quite some time.

DrMario - 28-10-2014 at 03:49

I work at two institutions. One has, what you would call, typical organic labs (some are analysis, some are synthesis labs). In that institution's labs I have yet to see any mineral acid bottles - but I certainly did smell some (once I opened one of the chemical cabinets I was inundated by a cloud of noxious something that had to be either nitric or hydrochloric plus random reagent aroma). The reason for the apparent lack of such acids is that here we do a lot of masspect in addition to LC and GC. Masspec is really one of the main competencies of this department, and apparently, inorganic acids are not compatible with it. Plenty of acetic acid though.

The other institution is kind of exactly the opposite: not much organic synthesis, but we use tons of hydrochloric, nitric, hydrofluoric, sulfuric and phosphoric acid. And H2O2. We use so much of these, that no bottle remains unopoened for more than 24 hours, except for week-ends, and these bottles (2.5L but more usually 5L) last for a week to less than a week, depending on the lab.

I've been working much longer with the latter institution, so my experience is "tainted" from there.

ziqquratu - 28-10-2014 at 18:00

Yeah, I know what you mean - there are big differences in acid usage between my current and former workplace. I, too, remember the joys of opening our corrosives cabinet and getting a nice big lungful of acrid fumes - or brushing against the inside reaching for a bottle at the back and coming out with a nice big streak of damp, corroded (and still corrosive-covered!) metal sludge on my arm! Funnily, OHS never picked that up...

I assume you want the small bottles for workplace 1; if you can just fill those small bottles in workplace 2, then you have no worries about storing the larger bottles. If you can't do that, I'd still recommend not risking your fridge by storing those acids in it. They're perfectly stable and, in tightly closed bottles, shouldn't be affected by evaporation or absorption of water from the air over any reasonable period of time.

Just for the record, though, I have no experience with HF, so my statements may not be appropriate for that! Definitely get advice on that from someone who knows how to handle it.

DrMario - 28-10-2014 at 23:26

Don't worry, I have no intention of storing HF! Very little use for it. Besides, any contact with HF, however minor, results in a mandatory night at the hospital. The nice thing about HF, though, is that it's less volatile than HCl, and that most metals corrosion is self-limiting (most metal fluorides aren't water soluble).

Thanks to this fruitful dialogue, I have now removed the HCl from the mini fridge, made sure the cap is tight, and put a little parafilm on it for good measure. I can't detect any HCl gas at all, so far.

ziqquratu - 29-10-2014 at 14:33

Yuh, had the experience of being exposed to HF (from hydrolysis of NH4F). Fortunately avoided the hospital - just had to wear a glove full of calcium gluconate gel for 24h (including passing through airport security... fun times explaining that!)

Are you saying you're now storing it out of the fridge? If so, I'd say great.

If you're saying you parafilmed it up and put it back in, keep in mind my original story - ours was ruined by a VERY well sealed (sure-seal, parafilm, cap, parafilm) bottle of thionyl chloride. I really don't think you can seal these things well enough to prevent sufficient leakage. It is a completely closed system inside the fridge, after all, so the acid vapour will eventually make its way to any unprotected metal.

CuReUS - 30-10-2014 at 03:03

Quote: Originally posted by DrMario

. Besides, any contact with HF, however minor, results in a mandatory night at the hospital..

Yuh, had the experience of being exposed to HF (from hydrolysis of NH4F).

yes ,HF is a toxin in the body becaue the flouride ion messes up with the calcium metabolism of the body ,and since calcium plays a vital role in nerve impulse transmission(acetyl choline etc) ,all your muscles and even your central nervous system could be affected

Quote:

Fortunately avoided the hospital - just had to wear a glove full of calcium gluconate gel for 24h

isnt calcium gluconate also used against spills of magic acid and flourosulphuric acid

[Edited on 30-10-2014 by CuReUS]

DrMario - 30-10-2014 at 09:00