Catalysis, Promoter & Poison - Chemical Kinetics Video Lecture | Chemistry for GRE Paper II

hello friends this video on surface
chemistry part 10 is brought you by exam
viacom no more fear from exam now I will
talk about a topic called catalysis so
what is catalyst so we have seen the
catalyst and nothing but substance which
by its mere presence increase or
decrease the rate of reaction without
being itself used up so they take part
in the reaction they form intermediate
or sometimes but they are not being used
up it's the substance which by its mere
presence increase they increase the rate
of reaction it was malaria for teammate
weight 130 may be the rate of reaction
is increased just by its mere presence
and they are called catalyst right and
this action of catalyst to change the
rate of reaction is called catalyst it
great here catalyst is nothing but
action of catalyst order of chain rate
of reaction this is called catalysis
correct for example nickel is used in
hydrogenation to increase the rate of
reaction the next example is
decomposition of potassium chlorate see
visions potassium chlorate kclo3 it will
decompose into KCl and oxygen this is
the bath reaction now without catalyst
it will need a temperature of almost 800
Kelvin but if you use a manner do the
same reaction will need almost 450 or
480 C we see the temperature requirement
has decreased earlier some 800 was
required or more than 800 now only 480
Kelvin is required for the same reaction
so here M no.2 is a
catalyst another reaction can be to
produce ammonia
I have n2 + 3 H 2 gives 2 n is 3 it
doesn't happen on it so on but if you
use this iron catalyst the reaction is
fast so here I am is a catalyst in this
reaction also we have seen the platinum
electrodes used for later lattices there
is also for example of catalysts enzymes
in our body is a very good example of
catalyst because these enzymes are used
to digest food and these nets are also
used for various functions in a body
like if you talk about this word
catalyst this word was Cohn coined by
mensch listen in 1835 so this guy was
studying the effects of foreign elements
on various reactions and he coined this
term in 1835 called catalyst when we
talk about catalysts we have two things
we have promoters and we have poison so
one which enhance speed of reaction and
one which slows down the speed of
reaction Hey so promoters they enhance
the activity of catalyst and poison
decrease the activity of credits and
let's understand this see for a reaction
we have something on catalyst right
these catalysts will either increase the
speed of reaction or will decrease in
speed of it correct now to to change the
impact of catalyst if you use promoter
or you can use poison
so if you are using a promoter the
catalyst which was supposed to increase
the reaction will increase the reaction
or the more if you use the promoter for
the catalyst which is decreasing the
react rate of reaction it will decrease
the rate of reaction or the more
similarly poison poison is to decrease
the effect of catalyst right so for a
reaction where you are using a catalyst
to increase the rate of reaction you are
using a poison it will minimize the rate
of reaction it will I mean the catalyst
will be there the reaction will happen
but to help in controlling the rate of
reaction because see it is like this I
know I have a catalyst catalyst can you
calculate of reaction but now if I want
to control the catalyst activity so in
that case we can use promoters and
poison if you use some promoters the
activity can accelerate the activity in
green as the activity of the catalyst if
you use a poison you can decrease the
activity of the catalyst right so poison
and promoters has to be clogged with
catalyst they can't be used alone
example this n is 2 + 3 h2 if you use
iron as a catalyst I will be the
catalyst to give ammonia right here my
molybdenum it acts as a promoter to the
island it act as a promoter
this iron is my catalyst so hope you
understand a different calculation
promoter catalase is something which
impacts the rate of reaction without
getting it impacted on its own now the
rate of reaction is impacted by the
catalyst if you want to control the rate
of the impact what we can do is we can
use them promoters or poison with that
we can actually impact a change this
catalyst behavior so if you use
molybdenum it act as a promoter and the
iron catalyst acts all the more better
right again the reactions I can use
example
hydrogenation reaction window right I
have a Lou Keane you use hydrogenation
planes of platinum catalyst alkane
correct so here I can use sulfur or
these guys are poison it is a poison
this is a platinum is a catalyst so
these poisons help in controlling the
rate of reaction for example no other
kind if I do a hydrogenation just in the
presence of platinum catalysts you'll
get hulky but instead of alkene I want
alkene right I want to remove only one
hydrogen bond this has three hydrogen
bonds you get or the two hydrogen bond
is gone and you get alkene but if I want
to give it make it alkyne
I want only one hydrogen bond to go the
presence of catalyst again platinum I'll
use poison right I can use sulphur or
arsenic woman use this episode for the
arsenic then my alkyne will be converted
into alkene so lindlar catalyst is
another good example of my poison
correct so these are the poisons which
helps in controlling the rate of
activity of gaseous razón the activity
of catalase is impacted by promoter and
poison these impact catalyst right these
are the one which impact the catalyst
you don't end of the day since Nam see
these promoters and poison impact the
catalyst and catalyst in point impact
the reaction rate so end of the day they
help in controlling the rate of reaction
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