Sunday, December 14, 2008
What is a liquid?
I recently had dinner with some chemists and after a bit of red wine the question "What is a liquid?" popped up. The reason the question popped up is the gas sulfur hexaflouride. I had never heard of this stuff before but allegedly you can float solid objects on top of it. Intuitively, I would say that if a ship can sail in it it's a liquid but things clearly aren't that simple. There's quite a few videos with this stuff on the web. In this particular video they float an object on some SF6 in a fish tank (I'm assuming the video is not a hoax). So what is the definition of a gas/liquid? Obviously it' a density thing. Did anyone out there pay attention when they had physical chemistry and would they care to explain it to a simple preparative chemist? Also what is the least dense liquid out there? Besides pentane (0.626 g/cm3) I can't come up with much that has a density below 0.7. D!