• Question: Do you know what dry ice is?

    Asked by Marragh to Nathan on 11 Feb 2015.
    • Photo: Nathan Quinlan

      Nathan Quinlan answered on 11 Feb 2015:

      Hi Marragh. Most things can exist as solid, liquid or gas, depending on temperature. For example, water can be ice, liquid water, or steam. Most things go from solid to liquid gas. Carbon dioxide (CO2) is unusual. It’s one of the main gases in the air that you breathe out. If you cool it down, it turns directly to solid instead of going through liquid. Dry ice is solid CO2.

      Dry ice is famous for making lots of thick steamy-looking stuff. When you put a piece of (very cold) dry ice in contact with warm air, the stuff at the surface will instantly warm up and turn into gas CO2. That wouldn’t normally be visible, but when it leaves the solid surface it is only just gas – so I reckon (I’m guessing a bit now) that there are some tiny solid CO2 crystals in the gas too, like little dust particles, and that’s what makes it look white and steamy.