L9 : Adsorption Numerical - Surface Chemistry, Chemistry, Class 12 Video Lecture

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let's take some numerical the question
is why substance like platinum
impaneling often used for carrying out
electrolysis for aqueous solution the
question is so we use some time this
platinum or platinum metal right why
see these are inert these are inner -
they don't take part in the reaction
right now the question is what is their
inner why do we need them see you later
dad everything is depending on surfacing
you know right is all again so basically
as importantly so these platinum of
platinum they provide surface leave the
provides surface area for reaction to
happen since they are more surfacing at
the moment you have platinum or platinum
surface areas more the reaction is
possible because everything is
applicable surface right if there is
more surface area reaction is costume
but they access they do not take part of
the reaction the question is why is my
physical adsorption decrease with
increase in temperature see is a tone
that physical absorption this is what
exothermic correct detached follow isn't
zero now if it is exothermic then as per
my Lee chart your principal right
principle we know that what happens see
this is exothermic you increase the
temperature the reaction goes in
backward direction they actually goes in
that direction that means the rate of
reaction decrease if you increase the
temperature okay this is true for
physical adsorption but for chemical
adoption it is pretty difficult because
they also if you see it's exothermic
process but there you need more heat
because the reaction the bonds are
formed
the bonds are broken so the activation
range is high so you've revised it a bit
of heat so the activation energy is east
and the reaction goes faster with a
different concept rate here it's all
wonderful for our nationalism author of
activation energy so ass pretty simple
game here so surface is the surface
energy is decreased in the etheric
process and that surface energy decrease
comes out as heat and it becomes
incoming process the moment you eat the
whole system as per liter to a principle
the reaction moves the backward
direction and then the rate of reaction
degrees and I says why are common
substance more effective and solvent
then they push like home they don't that
adsorption is directly proportional to
surface area right now it is powdered as
a bit so the surface area is increased
ordered means more subtly if we talk
about this example I have a cube 3 by 3
3 by 3 meter whatever you want you can
say let's take by 3 centimeters right 3
by 3 and when you break into 4 then you
break into 19 right so this is broken in
19 to 9 this becomes 1 by 1 but their
harmony 1 2 3 4 5 6 9 9 to 3 27 so we
have 27 piece and this is one piece
let's find the surface area in this case
surface area is what 6 a square there is
6 into a into a there is 54 centimeter
square let's find the surface area in
this c41 the surface area is what 6 into
a square a is 1 into 1 that is 6 but
they are total 27 cubes now write the
total surface area will be 27 into 6 you
solve it you get 162 is in Dvinsk where
you see earlier the surface area of 54
the moment you grind it you break this
one busy to 9-piece 27-piece the surface
area degrees to 162 centimeter square
thus the same amount of substance is
same in both case right this end
but the only difference is you have
broken it into small piece the surface
he has increased from 54 centimeters
quite new 1c to 2 centimeter square
that's why we see that the more reporter
substan the more is a surface area
correct and those we use powder
substance for adsorption and we call
that activated adsorbent see the next
question is seen the next question is
what do you understand my activation of
my adsorbent and how it is this
activation of adsorbent means what to
increase that zorbing power of adsorbent
right did we write here to increase
adsorbing power or ads or mega what can
be achieved is what we have seen that in
key surface area and how will you do
that by breaking into places you just
saw right just now here's some this has
less surface area this has more surface
area
the second thing also we use is we use
some specific treatment what is that
see if I have this charcoal what I can
do is I can heat this at a high
temperature let me almost 1000 Kelvin so
but then maybe the moment you eat this
chart for the high temperature what
happens in all the gases that are
adsorbed or expended right
that means more room for new ads or rate
this was my enjoyment the moment you
heat it up all the adsorbent is gone
right all expelled
it means you remove room for its orbit
now why adsorption is always exothermic
they told exit applicants were still -
less than zero that means heat is gear
not as I told that during adsorption
what happens is the surface energy is
decreased right these particles are not
allowed to move Hey
so the adsorption leads in the decrease
in the residual force on the surface of
adsorbent is my adsorbent so this
decrease in surface energy comes out as
heat it does it is extra right that is
one explanation
the next logic I have is the intro of
the system is decreasing right because
the movement of the particle is
restricted correct and since adsorption
is happening when delta T is also less
sensitive that means the reaction is
happening it's spontaneous
correct so Delta G is less than zero the
best reaction is happening if we're
talking about the scenario a reaction
happened I know that Delta G is nothing
but Delta H minus T Delta s this is
negative this is negative this has to be
negative
correct so this we can say that Delta H
is the idea that means it is a totally
so our absorption is always excellent
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