okay so today I'm talking about platinum
and platinum is used in things like
jewelry but probably more importantly or
certainly more importantly from the
point of view of chemists is used as a
catalyst that was a very good catalyst
for a lot of reactions which means it
speed up reactions Platinum is an
enormous Li and reactive element doesn't
react with air so if you have a lump of
platinum it stays the same for years and
years and years so what I have here is
platinum gauze so it's a very fine
platon gauze at the end of stainless
steel wire and we're going to use this
as a catalyst to decompose some methanol
in France locked away in a safe there is
the international kilogram a block of
platinum which defines what we mean by
kilogram and every few years they take
it out and weigh it just to make sure
that all the balances and everything
else haven't gone out of calibration and
you can do this because platinum doesn't
react with the air doesn't react with
water and so on but even so I think they
keep it under an inert gas to be doubly
sure Platinum is quite expensive this
piece here is very thin actually it's
actually very thin so there's not a hell
of a lot of platinum in this I'm going
to put this platinum and contact what
method our vapor going to heat it up a
little bit and it's going to drive the
catalytic decomposition of the methanol
producing formaldehyde hopefully that
reaction is going to generate some heat
and hopefully the Platinum is going to
get hot enough that it's going to set
the methanol vapor on fire I was once
invited all there was a chance to go on
to tour to go in down the Platinum mang
but I decided not to go firstly because
you had to get there at 7 o'clock in the
morning which bit early for me and
secondly because you had to strip naked
at the end just to make sure you weren't
stealing any of the platinum
full body search why didn't you want to
do it very well
even professors are modest so here on
the real you can see at the top end a
really beautiful sample of research
quality platinum platinum is a very very
precious metal it's a very very high
value not just for jewelry but also for
the production of auto catalytic
converters and other chemical processes
so I'm going to heat up their platinum a
little bit and then I'm going to pop it
into the flask Platinum is also used
very widely in catalytic reactions if
you expose methanol methyl alcohol to
platinum in the presence of air the
Platinum gets hot because it catalyzes
makes the reaction between methanol and
oxygen go much faster so what happened
was I heated up the Platinum a little
bit put it in into the atmosphere above
the methanol and the methanol molecules
hit the Platinum surface and start to
decompose the second reaction that
happens is when it gets hot enough
methanol vapor can actually start to
combust can start to react with oxygen
inside the flask that was the pop that
we heard
pop was the oxygen being used up really
quickly inside the flask really quite
wonderful sample really expensive as
well as one gram left one gram of
platinum it's used in so-called glow
plug engines for model aircraft if you
have a model aeroplane and you want a
real engine the No then you don't have
room for spark plugs and things like
that that you would have in a proper
internal combustion engine but if you
use a small piece of platinum the heat
of the reaction keeps it hot so that the
fuel mixture will ignite just as if you
had a proper spark plug and everything
else catalysis by platinum take two so
we're going to have another go at
decomposing methanol by a platinum
catalyst Platinum is very expensive and
the reason is expensive is that it's
only found in very small amounts in the
ores a really good platinum all may give
you seven grams per tonne of rock and so
you need an awful lot of rock to get a
substantial amount of platinum and
you've got to remember it's a very dense
element so seven grams wood Platinum is
far fewer atoms than say seven grams of
lithium so we have a warm Platinum above
the methanol methanol molecules are
coming up hitting the Platinum surface
starting to glow platinum mines also
produce other so-called noble metals so
you get quite a lot of gold coming from
the mine in fact much of their profit
comes from the gold and you also get
palladium and rhodium and osmium though
those are usually less abundant than the
platinum
and one of the real worries is that if
we invent these new technologies
platinum fuel cells for cars whether
there be enough platinum in the world to
make as many cars as we want
now it's still going and we have a
platinum it's been
minutes the Platinum still down and sort
of methanol molecules of evaporating
slowly from the top of the the the
methanol so first I hit the platinum and
a decomposing platinum is also used in
electrochemistry there are lots of
reactions where you use an electric
current to split water to do other
electrochemical reactions and if you
want to have an electrode that is really
inert people use platinum the glow is
generated this this this reaction it's
quite energetic and generate some heat
so we're actually heating up the
Platinum surface as it goes along it was
discovered in some electrochemical
experiment which involved bacteria that
Platinum can stop bacteria growing and
this led to the discovery of a
anti-cancer drug pulses platon I better
get a muggy so this model here is not
very good one but will do for cisplatin
so you imagine the platinum in the
middle with four atoms around it in
cisplatin it has two nitrogen atoms here
two chlorine atoms there and if you want
to see how cisplatin is made we go
really good video of my colleague John
Moses and his group making it on the top
of Mount Snowdon the highest mountain in
Wales but the way that this works is
that the platinum we can react with DNA
in cancer cells and one of these groups
attacks one strand of DNA the other
group the other strand of DNA so that
DNA which allows cells to multiply by
the two strands splitting cannot split
because they're held together by the
cisplatin and so it is quite an
effective cancer drug it's been going
for a squad for quite a few minutes now
which is pretty cool
so it's glowing away there as the
decomposition happens so there there's
catalysis of methanol decomposition by a
by platinum