Sciencemadness Discussion Board

Saturated CaCl2 Ice Bath

boobmaan - 9-3-2012 at 15:00

Can a saturated solution of CaCl2, combined with cocktail ice, reach and maintain sub-0c temperatures?

Just curious... ;-)

tastyphenome - 9-3-2012 at 16:38

www.google.com

"lowest temp ice bath cacl2"

first link: http://en.wikipedia.org/wiki/Cooling_bath

first info paragraph:

A bath of ice and water will maintain a temperature 0°C since the freezing point of water is 0°C. However, adding a salt such as sodium chloride will lower the temperature through the property of freezing-point depression. Although the exact temperature can be hard to control, the ratio of salt to ice influences the temperature:

-10°C can be achieved with a 1 to 2.5 ratio of calcium chloride hexahydrate to ice.
-20°C can be achieved with a 1 to 3 ratio of sodium chloride to ice.
-40°C can be achieved with a 1 to 0.8 ratio of calcium chloride hexahydrate to ice.


thankyou

boobmaan - 9-3-2012 at 18:43

Yes. Google. Thanks.
The question was asking if a saturated solution of CaCl2 and block/cocktail ice can reach and maintain a sub-zero temp. I'm not talking about crushed ice or shaved ice. I'm talking about the ice you get at the supermarket or convenience store. Also, this is OTC CaCl2, not CaCl2·6H2O... I'm talking damprid.

In this thread:
http://www.sciencemadness.org/talk/viewthread.php?tid=10444#pid125424
chemrox says:
Quote:

My CaCl2 solution is in the freezer at -14*C which is about where I want it for the use I have in mind. I used really cheap dessicant from an RV supplier.

I have not asked chemrox on his procedure... Does anyone have any more advice/experience using CaCl2 & ice to achieve subzero temps? Would I just crush the ice and add the CaCl2? It seems to me that a solution would be easier, but I have no experience. I'm just trying to gather as much information as possible before expending resources! And I would rather not mess with acetone or Isopropyl to get the temp down...
Quote: Originally posted by tastyphenome  
www.google.com

"lowest temp ice bath cacl2"

first link: http://en.wikipedia.org/wiki/Cooling_bath

first info paragraph:

A bath of ice and water will maintain a temperature 0°C since the freezing point of water is 0°C. However, adding a salt such as sodium chloride will lower the temperature through the property of freezing-point depression. Although the exact temperature can be hard to control, the ratio of salt to ice influences the temperature:

-10°C can be achieved with a 1 to 2.5 ratio of calcium chloride hexahydrate to ice.
-20°C can be achieved with a 1 to 3 ratio of sodium chloride to ice.
-40°C can be achieved with a 1 to 0.8 ratio of calcium chloride hexahydrate to ice.


thankyou


[Edited on 10-3-2012 by boobmaan]

Bot0nist - 10-3-2012 at 06:47

You can get sub zero temps with most salt/ice baths easily.

The damp rid will hydrate when exposed to moisture...

Get a thermometer and dip it in the mix.

[Edited on 10-3-2012 by Bot0nist]

peach - 10-3-2012 at 08:05

According to this table of frigorific mixtures, dry ice like temperatures can be achieved with regular ice and dilute sulphuric.

I have actually attempted that, thrice, but struggled to get it below regular ice / salt temperatures. It'd be interesting for others to try and see if they can get it down that low. Perhaps the sulphuric I was using wasn't dilute enough, and the heat of further dilution was overriding the heat absorbed by the melting point depression.

CaCl2 AND NaCl?

boobmaan - 10-3-2012 at 13:02

What about a combination of NaCl and CaCl2? A saturated solution?

If so, procedure? Thank you!

Bot0nist - 10-3-2012 at 13:42

Procedure? Come on man, just make a saturated solution of the salts in water (till no more dissolves), add crushed ice and mix. Keep in the freezer for a bit to help. Then stick in the thermometer to see what you have. Experiment with ratios till you get what you need. Simpler than making ice tea...

peach - 11-3-2012 at 02:20

Buy a bag of ice cubes. Wrap some in an old tea towel and place on concrete floor. Smash to bits with the bottom of a pan. Put a tupperware box on the kitchen scales, weigh in some ice, pour over the corresponding amount of table salt, give it a good stir with a spoon, done.

If you have snow where you live, that's better. And you can guesstimate the salt ratio by eye once you've seen roughly how much it is.

I seem to remember 400ml of said mixture keeping the temperature in a dewar at -20 for about 45 minutes to an hour before it started going back up much. I'd had the dewar in the freezer prior to that I think.

If you don't have any snow, and don't like smashing things with pans, Mr. Evil Face Frosty is here to help.



[Edited on 11-3-2012 by peach]

boobmaan - 11-3-2012 at 11:01

lol. I had one of those too!(never noticed the Evil Face though ;-).

Thank you everyone!
Quote: Originally posted by peach  
If you don't have any snow, and don't like smashing things with pans, Mr. Evil Face Frosty is here to help.



[Edited on 11-3-2012 by peach]