Critical Opalescence in Carbon Dioxide
Fascinating demonstration of critical opalescence..
One feature of the teaching at Dalhousie University’s Physics Department is a laudable emphasis on demonstrations.
Visiting Professor Tom Duck there, I was delighted to be shown a demonstration I had heard of, but never seen: the phenomenon of critical opalescence in carbon dioxide.
In my previous articles I described the phenomenon in two immiscible liquids which is an exact analogy for the physics of critical opalescence in a pure substance. But it’s not what physics students read about in text books.
Michael: What are you going on about?
The phenomenon occurs when one heats a liquid in a container with a small amount of free space.
- As the liquid heats up, it expands causing its density to fall.
- The liquid also evaporates causing the vapour (gas) pressure to…
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