There are many instances where you will need cooling as part of the procedure, for example in recrystallisation, carrying out reactions at low temperatures, controlling exothermic reactions as well as in vapour traps.
0 - 5 oC
It is important to have a crushed ice - water mixture to ensure good conduction.
Crushed Ice - CaCl2.6H2O (2.5:1)
These baths are 'dry' mixtures and so conduction of heat away from a vessel will be inefficient.
Crushed Ice - NaCl (3:1)
Crushed Ice - CaCl2.6H2O (0.8:1)
Dry Ice - Acetone (propanone)
Dry ice can cause severe frostbite if it comes in contact with bare skin so insulating gloves should always be worn
. The baths should be made up with small pieces of dry ice and topped up with further dry ice periodically.
Liquid Nitrogen is a hazardous material that can cause severe frostbite in contact with bare skin so insulating gloves should always be worn. Because of the risk of suffocation liquid nitrogen should only be used in well ventilated areas.
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Cooling baths are very useful in chemistry labs for many reasons. In this resource we share various recipes for making cooling baths to temperatures below 0oC.
This resource is part of the interactive lab primer - lab techniques collection.
See more lab techniques or visit the interactive lab primer home.