L34 : Fuel Cell - Electrochemistry, Chemistry, Class 12 Video Lecture

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we will learn as a few itself let's
first understand the concept behind the
fuel cell so if you see the production
of electricity generally if we do now so
mostly I think it seventy percent of
electricity generation is done by
thermal power plant by a burning coal
that is not efficient way to produce
electricity but still it is a major
source of electricity right so there if
you see the chemical energy is converted
into heat energy then heat energy is
used to heat water and then creates
high-pressure steam and then it runs on
turbine and there is a dynamo - and then
dynamo creates electricity there is no
direct way of converting chemical to
electrical energy chemical to et2 again
mechanical mechanical to electrical
correct so that is not efficient also
plus that is full of polishing it image
start of politic gases which is not good
for health if you're looking for a go
green earth where you want of better
earth with less pollution we should go
for fuel cell right so the galvanic cell
that are designed to convert the energy
of combustion of fuel hydrogen methane
etc directly to chemical energy they are
called future so fuels are nothing but
they also galvanic cell because in
galvanic cell what we do don't think
they are burning cell is something which
is created by Galvin it is just in this
honor we have given this name Calvin
Excel so gerenuk cell is any same that
converts chemical energy to electrical
energy directly directly right so in
this case chemical energy of hydrogen
methane etc is used and this kind of
cell is called fuels right let's see one
combustion reaction of what like
hydrogen so if you see water how it
reacts water reacts with oxygen to
prepare
what so hydrogen react with oxygen to
form water and this is a spontaneous
reaction Delta G is less than zero
spontaneous reaction so you keep
hydrogen oxygen near when it will form
water and it'll generate some heat
energy also right and here if you see
the beauty of this is that for this
reaction there is a transfer of
electrons if you see internally what
happen is hydrogen actually we lose
electron or becomes H+ and gives to you
later right that is how happens hydrogen
becomes s+ correct oxygen also if you
see to take half oxygen it takes 2
electron and becomes o2 - and this H+
and OH - - react to form water
correct so if you see there was hydrogen
here there's an hydrogen here they both
gave two electrons what will happen they
become H+ and they became education into
h plus we have gone similarly I had this
oxygen here it took it in they gave this
and this is used by this oxygen right
half of I'm taking it's a person - to
form Oh - now if you see this
now if you see this hydrogen this
hydrogen is this oxygen combined and
they form water but if you see intially
they were the transfer of electrons from
hydrogen to oxygen and they form a bond
right you must have seen this reaction
so for hydrogen and oxygen they react to
form water and there is a transfer of
electron but this is the internal
transfer of electron it is of no use to
us but if somehow we
for this transfer of electron to happen
externally then we can create energy for
example let's separate this so we have a
hydrogen here which gives h plus an
electron hydrogen gives s plus an
electron and we have oxygen right which
has become let's suppose yeah this is in
need of electron oxygen somehow we allow
H+ to come here but oxygen if you want
via ask oxygen to come through a this
electron if you force electron to come
through a circuit we can produce current
because current is nothing but flow of
electrons if you attach a bulb air blood
will do so in this chamber let's suppose
V from hydrogen here and hydrogen breaks
into H+ and electrons electrons here we
pass me some more loudly hydrogen to
pass through here we have oxygen waiting
and electron be allowed to pass through
some circuit then we can produce current
correct so here there has to be some
barrier which will allow only H+ ions
and not electron neither hydrogen gas to
pass through there is difficult task
right because they have very small level
the size of electrons in size of
hydrogen size of electrons and size of
hydrogen gas is very very small
but there has to be something if you
want to generate electricity from this
source because if you can somehow just
allow hydrogen to pass through in there
but we don't pass allow electron to pass
through then the electron will obviously
come from this path some home to meet
this oxygen because it's hydrogen oxy
and they are dying to me hydrogen want
to meet oxygen let's suppose this is the
goal hydrogen has I doesn't want to be
talking in any all right but there is a
barrier and hydrogen is not allowed now
what hydrogen thought is if hydrogen can
actually break itself
into h plus an electron then it can pass
through how if you see if this barrier
is only allowing h plus ions then
hydrogen will say okay let me break into
two parts and let me at least go as h
plus ions and the electron will come
from some of the circuit okay it is like
you are going you are want to pass
through this place but you have a huge
baggage with you and you're not allowed
to go through the huge baggage
so what you do you will keep your
baggage here and you will go in this
path and your bag will come from some
other path but at least by the time you
come here you'll have your bag and the I
mean you you will be there in your bag
alot of there so zooms electron as a bag
if you are with the bag you are not
allowed to pass right but if you just
remove your bag this bag is the electron
you are allowed to pass and the bag we
come to some other path somebody will
take it and bring your back right and
this flow of electron will produce
electricity so now what this is
observers the size of hydrogen if you
see the radius of a hydrogen is nothing
but 5 1 2 3 4 into 10 to the power minus
15 meter that is the size of hydrogen it
looks very small actually 10 to power
minus 15 we talk about the size of
hydrogen ions it is 0.8 into 10 to the
power minus 15 meter talk about the
electrons the size is 2 into 10 to power
minus 15 meter so what for now since
everything is in 10 to the minus 15
meter just ignore this values because
everything is in 10 to power minus 7
meter now if you see hydrogen is almost
5 lakh times bigger than hydrogen ions
and even electrons is little bit bigger
than hydrogen ion it's a big mystery
right if you see these two if you
combine hydrogen electron it becomes
such a big thing and that's what you
have seen in the atomic model because
the whole thing is filled with empty
space it's all empty space there so if
you
bring this hydrogen into hydrogen ions
and electrons the size decrease a lot
from 50,000 it became almost 1 + 2 3
from 50,000 units and became 3 units
huge difference in size now if you can
create some holes here like the membrane
which we have seen right or net which is
of this must size let me this up 1 into
10 to the power minus 15 meter size that
means that allow H+ but little not allow
electron because from a hole off point
from a hole of 1 into 10 to the power
minus 5 meter radius size you the
electron will not pass because the
electron size is 2 into 10 to the power
minus 5 meter that radius okay so at
this level if you can create a membrane
which is of almost this range the radius
of the holes in that membrane is of this
range 100 K - Baba - 15 meter actually
then the hydrogen class will be able to
pass through electrons will not be able
to pass through hydrogen gas gas no
chance at all right and here we can
create some catalyst which can help them
to break if you have platinum catalyst
because hydrogen will not bring into H+
in E - so easily so we'll create some
catalyst and will help them to break
themselves into H+ any man science and
then since this membrane which we are
creating will be aligned to pass
electrons through sorry hydrogen through
hydrogen will pass through electrons
will take this route to come in the
current will flow let's see the example
of a fuel cell now so let's see the
construction of this so this is my anode
this whole thing is my Road actually
this is my ah platinum catalyst this is
my anode with a negative charge and this
is a cathode with a positive Here I am
selling some electrolytes this has some
electrolytes we mark this in dots or
slots they are made of lights and these
electrolytes will allow the movement of
charge because from here we will see
that H+ will move it will allow h+ 2
right there will be some catalyst the
brown one is a catalyst and this is the
Platinum catalyst this catalyst will be
used to convert h plus h 2 2 h plus ions
as I told there has to be someone who
will help them to decrease the size
hydrogen gas item will be converted into
H+ ions and electrons correct also I
told there will be some membrane the
green one is my proton exchange membrane
we call is a semi permeable membrane and
it's made from I know verse right and
they are designed to conduct H+ they are
designed to conduct H+ they will only
allow H+ they told h+ is very small size
they'll allow h+ and they'll block
electron hydrogen gas all these things
are long correct even oxygen because a
very small size right h+ is very small
size 10 to the power minus 15 meter so
this holes are very small it will allow
h+ only they so if you see this proton
exchange membrane they use fluoropolymer
nephron actually that's used to create
proton exchange membrane will not
discuss more into this let's understand
they are very very my new holes in this
that laws only Ashba science we are
dealing at that level 10 to the power
minus 5 meter level right now if you see
the hydrogen and the oxygen gas are
bubbled through you see my hair my
hydrogen gas and oxygen gas here my
hydrogen gas is bubble - here's my
hydrogen gas that is bubble through in
this and from here my oxygen gas
bobberts if you see hydrogen gas goes
and hits this catalyst so we see once
again hydrogen gas came and it is a fuel
my fuel is my hydrogen here you see
this hydrogen gas came and it has hit
this platinum catalyst now some of these
hydrogen gas will be broken into H+ ions
and E - electrons correct what we
understands because this platinum
catalyst will help it to Brooke so this
will break into H+ and emails I now if
I've told you this this proton exchange
membrane will only allow H+ ions it will
not allow a - ion to go so H+ ions will
pass through this and this electrolyte
as I told is something which allows s
plus ions to go through any positive
ions will go through it is my
electrolyte so this H+ ions will go from
here it will reach this position why do
this position I will explain with that
part also right because the electron
went from here to here and it is more
electron here they want to me this
electron back so they will come there
correct and now they send this electron
it can come till this point but it won't
be able to cross this green membrane so
what this will do this electron will
take this circuit path and come here so
the when it crosses this part the bulb
grows see once again it crosses this
circuit right the bulb will glow and
that's what electricity is now we have h
plus in E - and back that means now what
will happen is the oxygen is bubbled
from here now if you see there is oxygen
there's h plus h plus e minus they are
all combined to form water right and the
water will drain out correct let me
repeat once again this is fuel is my
hydrogen is a fuel it is it comes here
some of the hydrogen breaks this is the
the red one is my Platinum catalyst it
helps to break into H+ an email sign and
whatever is not broken it goes back from
this excess fuel path and this membrane
green member will allow hydrogen to pass
it will pass come here this stream event
will block electron to pass so this
electron
cross this path it might cross this path
it will produce electricity here and now
we have H+ ions in - ions here the
oxygen the air is bubbled here and now
they all combine to form water and the
water is out that is the logic behind
the future cut its efficiency is 70% if
we talk about the thermal power plant
efficiency is almost 40%
it is pollution free go green it's a
very very good way actually so if you
see the reactions lemonade
so at cathode is my reduction right so
if you see the cathode this is my
cathode side so here I had oxygen oxygen
it reacted with the electrons let me add
some water because water was here a way
it reacted with some electrons and forms
for o H - I'm a node if you see
oxidation happen hydrogen broke into H+
ion we have shown so we take hydrogen
will this Oh H - it forms over water and
pressure for it
correct so what our reaction is hydrogen
plus water is equal to h2o
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