The Unknow Phase of Matter

God lord but Steve Mould is a brilliant communicator of science.

I've never really understood super critical fluids - even though I've posted about them before, but today's video - especially the part from about 10:20 through 14:20 or so - makes for a brilliant explanation of why fluids go supercritical at higher temperatures.

The use of the entropy and potential energy graphs in combination lays out the argument for supercriticality brilliantly.

Thanks, Steve...thteve.

Freezing liquid nitrogen

I've done that.

Quite a few years ago, in class, I had some liquid nitrogen thanks to the parent of one of my students, and I was able - with the help of a vacuum pump - to repeat this demonstration in class.

I'm not sure my students were nearly as amazed as I was, but it's a singular occurrence for me.

Very cool...(pun intended)...

Solid =/= liquid

I don't think there's any way that you would get through the TSA screening checkpoint with a frozen water bottle even if you were able to argue that it's not a liquid but rather is a solid at the moment.

Scientifically, you'd be right...you should win...but I'm thinking you'd still lose.

In fact, I went and checked the TSA's regulations regarding checking ice through security...

Frozen liquid items are allowed through the checkpoint as long as they are frozen solid when presented for screening. If frozen liquid items are partially melted, slushy, or have any liquid at the bottom of the container, they must meet 3-1-1 liquids requirements.

I guess if you can get your frozen water bottle to the TSA screening checkpoint and have it still be 100% frozen, you can get through the checkpoint...but that's going to take some logistical work or an incredibly cold airport to make sure none of it has melted by then.

SMBC - Superman freezes the Gulf

There was an episode of Batman: the Animated Series in which the villains dump two barrels of stuff into a lake. The barrels rupture (as they are designed to do), and the lake freezes solidly...instantly... the waves are frozen, even.

All I could think when I was in college and rewatched that episode was that the heat of reaction of those chemicals must be hugely endothermic. That's the level of science dorky that I was...clearly was...not is...was.

And then, along comes Zach Weinersmith with his geeky Saturday Morning Breakfast Cereal which is a webcome largely devoid of math but with definite educational overtones.

Check out, for example this comic dealing with the heat of vaporization of water.

And laugh all the way to popularity.

Fire and Ice: a heat of fusion demonstration

Heat of fusion isn't a terrifically exciting concept to demonstrate. Usually it involves melting or freezing of water. Oooh....ahhhhh....zzzzz

But the use of the heat of fusion (or latent heat of fusion, maybe) to start a fire is pretty outstanding.

To explain the concepts...

• paraffin absorbs energy from the blowtorch or Bunsen burner 
• paraffin melts and starts to boil, releasing paraffin vapors (highly flammable, paraffin vapors)
• the ice water beaker is lifted to quickly cool and solidify the paraffin wax
• the paraffin wax had absorbed energy in the process of melting (heat of fusion)
• that energy is released when it solidifies again (reverse of heat of fusion)
• that released energy is enough to set the paraffin vapors on fire

How frickin' cool is that?

And messy, too...how frickin' messy is that?

Check out another version of the same demonstration...