L24 : Kohlrausch Law: Numerical - Electrochemistry, Chemistry, Class 12 Video Lecture

hello friends this video on
electrochemistry part 24 is brought to
you by exam for your calm no more fear
from exam so here we have to find lambda
M naught that means motor conductivity
at infinite dilution for CSEA given
mgesa 4 you will use this table so you
see lambda M naught or cacl2
as per called restore will be lambda e
naught of C 2 plus plus lambda M naught
off CL minus and then we - why because
CAC and - it will dissociate into C 2 +
I + 2 chlorine ions let's put the values
here that becomes CA 2 + 1 1 9 + 2 into
chlorine CL minus seventy six point
three what are the unit siemens
centimeter square per mole we solve this
you get this becomes 150 two point six
plus one one nine there is 271 0.6 C
means centimeter square correct let's do
the same thing for mgesa 4 so if you see
mgesa 4 it will break into mg plus 2
plus ions plus so4 minus ions correct so
if you want to find the lambda M naught
of MGS o 4 so as per called rock
slightly nothing but lambda I am NOT of
mg 2 plus plus lambda M naught of s
about to - so what is the value of mg 2
plus this is 1 0 6 x over 2 minus 160
and the unit is the same guy same in
centimeter square per mole so if you
solve this you get 266 Simmons
centimeter square it easy the next
question is the lambda I am not for any
CLS CL n any AC are given right we have
to find the lambda M naught of h AC C
NaCl will break into any plus plus CL
minus s here will break into h plus CL
minus and any issue will break into any
plus EC right so if you want to find the
lambda M naught of NaCl will be nothing
but lambda not of any plus plus lambda
naught off CL minus and that value is
given 120 6.4 unit is given that is s
centimeter square similarly lambda net
of HCl is given that is nothing but
lambda M naught of h plus plus lambda M
naught of CL minus and that is given for
25.9 Siemens centimeter square per mole
similarly this is given lambda net of
any AC is given that is nothing but
lambda naught of any plus EC minus and
that is given ninety one point zero
Siemens per square this is equation one
is in equation two and is in option
three now if you see if you just see if
we add these two equation if you add
these two equation second and third if
you add these two and then subtract the
first equation what will happen is we
will get lambda out of h plus CL minus
NF
plus a signal and from this we are
subtracting CL minus and ne plus correct
these two will go off and these two will
go up so if you what I am doing is I am
adding 2 & 3 and from that you're
subtracting the first equation by it's
what will get is the whole equation will
be getting is lambda I am NOT of h plus
plus lambda I am NOT of AC minus and
that value are getting is this Plus this
right for 25 plus 91 minus 126 point for
if we solve this you get three ninety
point five and unit will be s seen
square Carmel and this is what this
value is nothing but lambda I am NOT H
see because H AC will break into H a
plus AC - correct then that's what we
are able to find the lambda naught C
thus three equations quadratic equation
you just reframe this equation to make
sure that you get the value of more on
molar conductivity of H AC ad infinitum
the next question I have is the
conductivity of some mole of acetic acid
as given we have to calculate it's this
sufficient constant is we have to
calculate the alpha and K if lambda M
naught is given like C for to find the
value of K Lirio constant I have to find
alpha and alpha is what lambda M by
lambda I am NOT correct is that in
finite duration this is at any
concentration so lambda M naught is
given to us this value is given to us I
have to find first my molar conductivity
at this concentration what is the
conductivity is given K is given and see
also given so lambda is nothing but K by
Z so I can easily find as well once I
have the lambda M I have alumni event I
can find alpha once I have alpha I can
find keep little goes right so this is
what the acetic acid the equation is I
have ch3 Co H it will become ch3coo
minus and h plus right measuring c is my
initial concentration and after
equilibrium is reached this becomes CL v
is become Cl so my K will be what C
alpha square by 1 minus alpha by CL Phi
into CL Cabaye C 1 minus alpha by L we
have seen this so many times so I just
told this because this is nothing but
concentration of cscl co- into
concentration of h+ by concentration of
CO h so I need to find first one as per
my discussion I have to first find
lambda M so lambda M is what K by C
lambda M naught is given in C means
centimeter square per mole so will try
to find the lambda M also in this unit
what is the value of k k is given
conductivity is given this this is my
key in this messy k is my key that is 4
point 9 5 into 10 to power minus 5
Siemens per centimeter
this is mole per liter so this is point
0 0 1 0 to 8 moles per liter liter L
make it point 0 1 centimeter cube like
0.1 centimeter cube yeah sorry rate 1
liter is point once individual so with
this I'll get in the same unit so if we
solve this you get 48 point one five
Siemens centimeter square per
that is the value of lambda M this is I
have lambda M naught is given a take in
pin alpha alpha I have seen that by
kollross law is nothing but lambda n by
lambda M naught lambda m vs four forty
eight point one five five this is sorry
one five Siemens centimeter square per
mole this all unit divided by value
three nineteen point five same in
centimeter square per move these two
units gets cancer and this value you get
is point one two three three
once I have alpha I can easily find ke
ke is what C alpha square by K is C
alpha square by 1 minus alpha let's put
all the values C is what C is given that
is in point zero zero one zero two eight
and C please note here will be in
molarity moles per liter it will not be
in moles per centimeter cube or most per
meter cube and the alpha is point one
two three three square by 1 minus alpha
that is point one two three three so you
solve the values you get one point seven
eight into ten to the power minus 5 and
unit will be obviously moles per liter
why because this is unitless this is
glitchless so the unit of 811 will be
nothing but the unit of molarity
concentration in molarity is mole's per
liter the next question is the
resistance of a conductive cell consists
of point zero one MKC or solution at 298
Kelvin is 150 ohm so this is where the
instance is not existence this is my
concentration is my temperature what is
the cell constant the conductivity of
the same concentration the concentration
is same if you see at this is this so
this is my conductivity conductivity is
what K
right formula I know is our is rural why
this is the formula II know but Rho is
not given K is given I can say nothing
but 1 by k ly correct so in this case
let's see what will given a state is
given yes conductivity is given yes and
what is the cell constant this is cell
constant right so let me make it G Star
ready the formula I am going to use is R
is equal to 1 by K G star so the point I
am trying to say here is I don't
remember all the formulas I just
remember this formula R is equal to Rho
L by a and then based on whatever is
given if my conductivity is given I will
make it 1 by K if my LMI is given I will
make it
G Star right so I don't remember all the
formulas in this remember 1 formula R is
equal to Rho L by 8 this is the formula
of the using Dom so correct I have to
find one cell faster Easter so my G star
is nothing but R into K what is the
value of R 1 pipe double zero ohms what
is the value of K K is given this value
0.14 6 into 10 to the power minus 3
Siemens per centimeter Siemens and homes
gets cancelled you saw this you get
point 2 1 9 per centimeter and that is
my cell constant if you see says concert
is L by a so it's if you put length in
winter centimetre area and centimeter
square unit will come out to be one per
centimeter and that is the chip thank
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