Buffer Solution - Equilibrium, Chemistry, Class 11 Video Lecture

hello friends this video an equilibrium
part 42 is brought to you by example a
calm no more fear from exam before
watching the video please make sure that
you have watched all the previous parts
now I learn a very very interesting
topic called buffer buffer solution the
name sounds very fancy what is buffer
solution is the solution is nothing but
a solution which resists change in PH
even if you add some amount of acid or
base to it in the solution even if you
add some H+ ion it won't change the pH
or small H my design
it won't change the pH sounds very good
right so the solution which doesn't
change the pH even if you add some small
amount of h plus or minus signs so what
is the user buffer solution plays a very
critical role in a biochemical and
chemical process we will talk about that
if you see the blood blood example of
buffer solution it has a specific pH
even you are increased trying to
increase or decrease the X plus ions
considerations the pH won't change we
will discuss about the Bakker solutions
therefore kind of of Croatian strong
acid buffer strong base before weak acid
before Andy please discuss all these
strong acid buffer if you take very
strong acid like HTML 3h s CL they are
also a buffer with the low pH why
because even if you add something some
wash - iron that will be used right the
chain it will be very good it's very
very acid right since it is very strong
acid even if you add small drops of h
minus ion this would be used somewhere
it will be lost it will lost in
translation and you lost it will be
always acid same thing with the strong
base buffer if you have very strongly
NaOH requests then if we add small
amount of H+ ions it won't make any
difference in the pH this is strong
beans buffer but strong acid and strong
which is something which we don't want
right in real life you want something we
have to be paid but we has been weak
please if you normally add any
the servicemen science it will change
the pH watch video so far weak acids
well first we have to do something
different so what we do here is we take
weak acid and their sword in strong base
Lily how example my acetic acid is a
weak acid right and I take sodium
acetate it's a strong base it has a pH
of four point seven five Wisconsin and
how it is continued is that by this case
my acetic acid hardly dissociates so
most of the amount will be as weak as in
a very few amount of H+ MCS to you
Co minus ions may be there so really CSC
Co and able dissociate completely almost
so large amount of CCS 3 Co - and na +
PB there now if I try to add let's
suppose H - E what happened the moment I
ID OS - iron what will happen is we
combined with H+ ions can't combine with
any + no because if you see NaOH is the
strong base it wants to come be in na +
in a wish - 90% the case is here
but h2o is a very big thing so h+ + OS -
hardly 1% it always tries to be in this
part 99% white so it's all this nice to
be in this part in this case always
touch to be in this part so if you add X
plus h minus ions s + will take that and
form this and if you add let's suppose H
+ here then the ch3 Co - will take this
CH h and form ch3 Co if CSD CU h is
formed in more quantity now this
reaction will kick off and create please
quite a balance right if you eyelash
pressed CSD CO - is absorbing it if you
add H - especifically so we have readily
free ions to absorb extra h plus h minus
- that's why it's a buffer right so in
this case we see you I'd watch - ions
and they won't take h nurse will take
and form what if you had X plus CS v co
- we'll take it from CS 3
gee so even if you add more H+ handled
by a large amount it can with its and
lot of h+ ions because it's a bead acid
right similarly we have weak base buffer
so we have d paste + sort of strong acid
nation example in this case we have M
William chloride and ammonia hydroxide
my bps both ammonium hydroxide and then
I got ammonium so I know in this case if
I want to add H class what will happen
you combine with this guy
well what do i watch - you combined with
I just plus 1 to minus sielmann's here
right so in this case this can be its
and lot of H minus 10 lava so this is
this thing because we have more here
let's put less it can be send of H - if
you either base also in this it can
withstand the pH run more and more wise
- you're a little less can do it and it
won't like the pH to power and it's pH
is around nine point six ten questions
here you define the pH result mixtures
10 ml of 0.2 m cos 2 and 25 ml of 0.1
MHC
so we have this reaction c a.o HT + t HC
r delivering with the c SE n + twist
this is the reaction here right so at T
is equal to 0 what is the concentration
of this guy cos 2 n HCl that is
something here - fine so this is a sedan
is a base here right so first this base
this is acid react from salt and it'll
become either acidic or basic so let's
find the number of moles so we have 10
ml of point M cos 2 is nothing but 10
into 0.2 that is too many moles of CHD
smelly we have 25 ml of 0.1 that is 2.5
we move this off at CL all right let's
have this reaction first let's assume T
is equal to 0 i had moles of this 2.5
moles of this zero most of those
realises this that suppose takes x right
so it will take 2.5 - things to X
actually correct well this is 1 this is
2 is talking about the coefficient and
this will form x this is a formula now
if you see this is 2 since it want to
react what if X is equal to 1.25 then
hole of a seal is gone right if X can
have and went to five value also because
it's neutralization reaction so let us
assume X go to 1.25 so this become
two point five minus two point five that
is 0 that becomes one point two five
does he loves to point five and then it
comes to minus-15 goodbye right t is
equal to eight million gets it so if you
see this is zero now this has this value
is gonna ignore also indifferent ignore
that part so we have just as 0.75 milli
moans but we have to find the molarity
in all right so molarity is what moves
by volume personal volume 10 plus 85 35
so molarity off of cos2 is what we have
0.75 by 35 milli little so this becomes
in this point zero one this is what we
need there wasn't many moles and
milliliters or cancels and you get this
much molarity of the CH so now this
means after this reaction s seal is gone
I am left only with CA o h2 so I can
have this reaction now cos2 will react
to form c plus plus to wash my hands you
have to find the pH that means if I have
point zero two one four and zero here T
is equal to 0 T is equal to equilibrium
this will become 0 this will become 2
into point zero 2 1 for M correct so Y
is minus concentration is what point 0
48 M so I can find pH Poh is what - lava
this value point 0 4 this is nothing but
1 point reason my Poh is one point 3 7
th is what 14 minus one point three
seven that is twelve point six and that
is C in this case what happened was Co
h2 and HCV reacted the IC was totally
consumed we have only CST but the number
of Molossia still was lesser not the sum
of the cs2
to react with us here now with whatever
number of moles we have or ch2 we found
the number of
Oh H minus ions we'll get to that we can
find out th thank you
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