Dry Ice Facts
It's gas Jim - but not as we know it.
Dry ice is solid carbon dioxide (CO2).
It is very cold with a temperature of -78C. It derives its name due to the unusual property of turning from a solid to a gas (subliming) and it is because it does not pass through the liquid phase at atmospheric pressures that it is referred to as ‘dry’ ice.
The first published observation of dry ice was in 1835 by French chemist Charles Thilorier. He noted the formation of dry ice when a container of liquid carbon dioxide was opened.
Ice is made by pumping liquid CO2 at -20c and 20 bar through a nozzle to create CO2 gas and dry ice snow. The snow is compacted at high pressure (2,500 psi) to create pellets, slices and blocks.
The CO2 used is food grade and is non-toxic; it is the same chemical that gives drinks their fizz.
In the UK liquid CO2 is a by-product of the fertiliser industry. It can be argued that the use of dry ice is not making a net contribution to global warming because the CO2 involved is being re-cycled; if dry ice was not made the CO2 involved would be released into the atmosphere from the fertiliser plant directly. In some other markets CO2 for dry ice made by burning fossil fuels which is environmentally very harmful.
Dry ice density is around 1.6 g/cm3, however the bulk density is around 1g/cm3 – just like water!
The molecular weight of dry ice is 44.01
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