Sam and Neil have devised what to me is
a new experiment for Halloween it's
something that involves the use of
Neil's cauldron so here it is this is a
hemispherical analyzer from an old XPS
machine so XPS is x-ray photoelectron
spectroscopy Neil is salvaged this piece
of metal and added legs to it so he's
made his own which is cauldron and we're
going to do a reaction in it that really
is going to boil and bubble
there are a few steps to this the first
stage is actually to set up the lumps of
charcoal so we need to create our own
little barbecue in Neil's lab so Neil's
constructed a small barbecue little
grill and he's got pieces of charcoal
that he's made himself
the cauldron is filled with liquid
oxygen liquid oxygen boils 13 degrees
centigrade above liquid nitrogen that's
at minus 183 degrees centigrade as
always you can see that the liquid
oxygen has a nice slight blue color to
it and the reason it's dangerous is that
it's very concentrated oxygen and
therefore it can make things burn very
dramatically and I was really quite
worried about this experiment because I
had seen cotton wool reacting with
liquid oxygen and you may have seen it
on one of our videos poof and then we've
also tried reacting charcoal with
gaseous fluorine f2 and that burst into
flames pretty dramatically as well so I
was quite worried about what would
happen when you dropped red hot charcoal
into liquid oxygen
it's a beautiful reaction so so free you
can actually see they start out glowing
red hot then it was kind of orange and
it was getting hotter and hotter as the
reaction progress and so by the end of
it that small lump of charcoal that
remained was actually glowing white-hot
because it was that hot in there it's
giving out a huge amount of heat you can
see the charcoal is glowing really
red-hot so it means that the reactions
going quite fast but it swims around on
the surface almost peacefully and I
think the reason is because the charcoal
is so hot it is not actually in contact
with the liquid but is floating as it
were on the cushion of oxygen gas rather
the same thing that happens if you drop
water onto a hot metal plate it runs
around but it vaporizes quite slowly so
what you're actually seeing is the
reaction of charcoal with oxygen in what
turns out to be quite a nice controlled
way definitely go again
in some ways it's a much more satisfying
reaction than an explosion because an
explosion happened so quickly that even
with a high-speed camera you only get a
few frames but with this reaction you
see it skittering around and you have
time to think about what's happening and
anything that makes you think is good
yes that's it exactly that that's what
we wanted you to film as well
look at all Duras well I think his
cauldron is really rather fun and it
might be quite interesting to try
reacting some other things with liquid
oxygen or other liquid gases be quite
fun to try filling it with liquid
ammonia but then we'd have to do it in a
fume hood or the whole building would
have to be evacuated