Dry Ice – safety and suppliers

While dry ice is great fun to experiment with, safety is very important. Please treat it with the respect it deserves and take note of the instructions and information below.

SAFETY

  • Dry ice is very cold (minus 78.5 degrees Celsius).
  • As such it should not be handled with bare hands or eaten while solid.
  • It is so cold it can cause burns and blistering.
  • Keep away from kids and pets.
  • Do not dispose of down drains or in sinks. When the dry ice makes contact with water in the drain it will freeze and as it does so the water will expand, which may result in damage.
  • Do not enclose in airtight containers. Always allow gas to escape. When storing dry ice, leave esky lids loose at all times.
  • Use in a well ventilated area. When transporting ensure fresh air is available for the driver, passengers and pets.

Scientific stuff

Dry ice is actually frozen carbon dioxide. Unlike water that can express all three phases (solid, liquid and gas) – on Earth, carbon dioxide has a gas phase and solid phase, but no liquid phase. This means as it changes from a solid directly into a gas (a process called sublimation) which results is no “liquid” and therefore it is termed “dry” ice.

Dry ice is colourless, slightly acidic and has a zesty odour. It is mainly used to refrigerate food or lab samples, for flash freezing or for shrinking pipes and metal in manufacture.

Adding dry ice to water increases the speed of sublimation and can make the water acidic (not dangerously). As the carbon dioxide changes to gas some of it dissolves into the water and produces carbonic acid (a weak acid). This change can be seen if an indicator such as universal indicator or a pH meter is used.

As dry ice is constantly changing from a solid to a gas it doesn’t last very long. At the time of purchase you may have an esky full of pellets while 12 hours later you won’t. This means three things:

  1. you should never put dry ice in an airtight or enclosed space as it will cause an explosive effect (due to built up pressure as gas takes up more space than a solid).
  2. you should only keep and use dry ice in a well ventilated area (as carbon dioxide can cause hypercapnea – too much carbon dioxide in the blood).
  3. if using the dry ice sometime after purchase, you should buy more than you need to counteract sublimation rates of your dry ice.

For more experiments you can try with dry ice, click here.

Suppliers

Dry ice can be purchased by the kilogram from the following businesses. It is suggested you call ahead to ensure they have stock and take your own esky so your dry ice is well insulated.

Dry ice can cost between $12 and $20 per kilo.

Australia wide – http://www.boc.com.au

South Australia – http://www.dryicesupplies.com.au

New South Wales – http://www.mriceman.com.au