Cooling mixture

Cooling mixture prepared from substances, melting or dissolution which there is a significant absorption of heat. To quickly achieve a constant temperature cooling all the cooling mixture of a solid shredded and mix carefully mix. Moderately low temperature give O. E., in which 100 g of ice (and snow) take sodium chloride (table salt) 33 g (temperature maximum cooling is 21.2 degrees), ammonium chloride -25 g (-15,8 degrees), ammonium nitrate - 45 g (- 17, 3C degrees), sodium nitrate - 59 g (to 18.5 degrees), calcium chloride crystal to 143 g (-55 degrees).
For more low temperatures used O. S. of solid carbonic acid with the addition of organic liquids with a low freezing point (ethyl alcohol, chloroform, ether, methyl chloride). They are added to improve contact with a cooled surface. In this case achieved temperature from -77 degrees to -82 degrees. Deeper cooling give liquid air (-186 degrees) and liquid nitrogen (-196 degrees).
Cooling mixture are mainly used in laboratory practice.