It's winter break here at Princeton High School (in Cincinnati, where you friendly, neighborhood blogger teaches), and that means a whole bunch of students hanging around at home in need of chemistry learning opportunities.
I'd particularly recommend making your own gel window clings (easy, kid-friendly) and the copper-plated Christmas ornaments (higher degree of difficulty).
I've made the ornamnets before, and they're a blast.
She's pretty lucky there that she didn't get a serious injury, admittedly.
But...
There's a significant mis-statement in the title of the video. The Coke bottle doesn't explode at all, not even a little.
What happens is that the liquid nitrogen poured into the bottle changes from liquid into gas. That's happening all the time at room temp. You have to store liquid nitrogen in what's called a dewar flask (the metal thermos that the 'scientist' is pouring from) because it insulates the liquid nitrogen from the heat of the surroundings, slowing down that process.
When the liquid nitrogen is poured out of the flask, it boils very quickly. When it boils, it changes from liquid to gas and expands drastically.
If there's nothing in its way, that expansion is no big deal. It pushes against the air; the air moves; all is well.
If you pour it on top of Coke, the liquid nitrogen (being less dense than Coke) floats and is open to the air. Again, no big deal.
If you invert the bottle so the liquid nitrogen floats upward to the sealed end of the bottle and has Coke below it, suddenly the liquid nitrogen is trapped. The expansion now has a problem because it has to push its way outward. In this case, the expanding gas pushes the Coke out of the now-upside-down bottle. According to Newton, every action (Coke pushing downward) has an equal and opposite reaction (pushing the bottle upward). Check out conservation of momentum if you have issues with that.
Because the Coke being pushed downward has mass and is moving, it produces force. Again, Newton F=MA. The plastic bottle has very little mass, so if an equal force is pushing the bottle upward, (equal F, smaller M) we get a much greater acceleration (A), so the bottle shoots upward very quickly.
As long as the bottle is flipped definitively and quickly...and it's pointed directly upward with nobody's face above it...it should be safeish.
The host didn't flip quickly. She paused because she was rightfully afraid.
The host didn't point the bottle directly upward. She rightfully wanted to move away, so she tipped the bottle and moved away at the same time.
Don't mess around with liquid nitrogen in sealed containers, folks.
See, it's funny because the phrase 'splitting the atom' often refers to nuclear fission, the literal splitting of the atomic nucleus, creating two daughter atoms from a single atom, typically converting a small amount of mass into a large amount of energy.
