Kind: captions
Language: en
[Applause]
boiling point is something that we
normally think of as a stable property
of a substance but it really depends on
what the pressure is around the
substance so for example water only
boils at 100° C if the pressure is one
atmosphere so if you reduce the pressure
then those water molecules that are
going quite quickly can easily escape
from the water if there's no pressure
pushing down on them so you can get
water to boil at room temperature this
is really boiling water the funny thing
about boiling water at room temperature
is that it actually decreases the
temperature of the water that's because
all of the fastest water molecules
Escape leaving only the slow ones behind
we're refrigerating the water
refrigerating the Water by boiling it
yes yes that is a cool concept I know
everyone's a big fan of liquid nitrogen
but I've never seen solid nitrogen so we
use the same trick pumping out the very
fastest nitrogen molecules and
eventually that decreased the
temperature enough that the nitrogen
actually
froze
no I'm putting a uh thermocouple in
there so we can measure the temperature
of our liquid nitrogen and it
reads
uh okay so the temperature of our liquid
nitrogen is aboutus 196 CS which is
exactly what it should be and now we're
going to uh Evacuate the chamber we're
going to suck the air out of
there you can see that the the nitrogen
is boiling
okay the temperature it's the
temperature is dropping minus 199 minus
200 nothing we're coming up on the
triple point of nitrogen yeah I don't
know no
no maybe
not we are forming solid nitrogen
pre the ice is actually getting sucked
up by the reduced pressure up here and
there's a higher pressure underneath the
ice because the vacuum pump hasn't had a
chance to work
there I've never seen solid nitrogen
before the
nen after creating the solid nitrogen we
poured it onto a water bath and we got
the whole surface so cold that carbon
dioxide actually condensed out of the
atmosphere and we formed solid carbon
dioxide dry ice on the surface of the
water
[Music]
for
wa
we have a solid piece of
CO2
and
[Music]
jaser
[Music]
H but
the world should feel the same fres of
refence slide off the tip of the pencil
called inal FR usually many layers