Measure Electrode Potential of half cell (Part - 8) - Electrochemistry, Chemistry, Class 12 Video Lecture

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electrochemistry part 8 is brought to
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no more fear from exam now the question
is how do we measure the electrode
potential of other using standard
hydrogen potential electrode so let's do
that
see if you see at STP at 298 Kelvin I am
talking about at 298 Kelvin my room
temperature see the email of the cell
for this cell will be one this is my
anode this is Kappa so this will be a
hydrogen electrode standard hydrogen
electrode and double bar and they said
this I am my second half in the cell
right this is my cathode
the first question is why did I took as
a naught why did I took as h ee by a
standard hydrogen electrode as anode see
we need to find reduction potential
because the electrode potential is
nothing but induction potential correct
and IUPAC says reduction petition is
nothing but electric potential now if I
keep this as my cathode cathode I swear
I have reduction half right so if you
see II sell whatever we will get from
this is ear adduction that is this value
minus EE oxidation is this guy no.2 and
that is nothing but zero so what will
happen in that case this value is
something we should get experimentally
this is unknown so we do not have to
apply a negative sign so whatever value
we got experimental that becomes by ear
adduction so if you just flip it then
what will happen this becomes zero minus
e oxidation you assume this guy is oxide
oxidizing in that case you have to apply
a negative sign again unnecessarily just
to make things
simpler you can actually do it as a
round also but just to make things
simpler
I'll take standard hydrogen electrode
sn1 because anyway I am trying to find
the reduction potential reduction
happens at cathode so that that be a
known correct
so let's find this for copper so this is
my copper I'll dip in copper sulfate
solution the reaction of the cell is
like this so here I have oxidation
happening right that is my platinum
coated hydrogen gas will get converted
into H+ and double slash this S Plus is
my liquid light here HCL or hbr one mole
and then I have a copper sulphate
solution this C 2 plus is my left right
here and I get copper reza
or this is my reaction right this is my
whole cell representation and this both
h plus is 1 m and in copper block is
also on it because i'm talking what
standard things now all 1em 1em
correct so for this what we get is e CL
is nothing but e reduction minus e
oxidation and this is zero so
experimentally will get this bad so e
cell is nothing but e reduction that is
my Cu 2 plus 2 copper minus e reduction
in this case e reduction potential of h
plus 2 H is 0 and E cell experimentally
will found this to me
point 3 4 put so with this I can say
that e Cu 2 plus 2 cu this reduction
potential of copper two plus two copper
and nothing but point 344 to correct
that means for this reaction copper 2
plus occurs one mole to copper solution
obviously two electrons you need
the e-value is 0.34 correct
now since note one thing here is since
we assumed this hydrogen to be zero
actually this is not zero right this is
four point four volt actual value but
since this we assumed to be zero so we
can't actually say that the standard
electrode potential of this is this we
can say but this indicate this positive
value of this indicates that copper plus
two ions get reduced more easily than
edge presses it just indicates that
copper plus two ions can get more easily
oxidized so it can more easily reduce to
then it's precise because it has a
positive reduction potential positive
reduction prevention that means copper
two-plus easily gets it used to copper
as compared to H+ ions to I do hope you
understand see Cu 2 plus 2 cu this has
the value of 0.3 forward and I am
assuming H plus 2 H has the value of
zero what does it mean if you compare
this anyway this was assumed since this
was assumed I got this value right for
the dependent complete these two
equation this you can say that this
positive value means means this reaction
is physical correct more feasible zero
means okay types when you compare these
two this 0.34 is more than zero that
means this reaction is more feasible
more spontaneous I can say a first
reaction is more spontaneous than second
reaction that implies that copper
two-plus can easily us reduce to copper
if you compare this with hydrogen plus
it if you compare h plus and Cu 2 plus
out of these two it is Cu 2 plus which
will get reduced not H
why because cu+ to see you it is 0.34
volt it relays more energy gives free
energy change is more negative it's more
feasible right not becoming reduction
correct hope you understand that means
if you have in solution h + NC youtube
plus it is Cu 2 plus that will become C
you
it is not H together to become a ch2
right that means if I have s CL and I
have copper si will not be able to
dissolve copula as CN will not be able
to dissolve copper because I should ask
H+ is not strong enough to convert C to
Cu 2 plus like Cu 2 plus can is easy say
C 2 Cu 2 plus 2 cu is more easy than ice
plus 2 H 2 right because for this to
dissolve H+ has to convert to s 2
generally reaction will happen that will
not be feasible correct let's find the
same thing for zinc now so instead of
copper will put zinc here and will put
zinc here now since we are putting zinc
in the reduction side so we will write
the reduction reaction of zinc correct
so here the equation of the cell will be
what my platinum surface my hydrogen gas
one mole becomes s + of one more double
bond my zinc plus of one more will
become zinc is one more necklace this is
a reaction and this is the whole
representation the cell right for this
cell yourself what your right - e of
left that is e of gel n 2 plus 2 jink
reduction - II of hydrogen so cheap
and experimentally this value is how
much - point seven six volt that is
nothing but your genuine - plus zinc -
zero so the reduction potential of zinc
is minus 0.76 but right now the negative
value of the standard electrode
indicates that H+ ions get reduced more
easily if example law we talk about
these two reaction this NH plus 2h this
has the value of -5 7 6 and they serve
the value of zero out of these two which
one is more obviously the second is more
because this is negative value this is
neutral value second reaction and Wanda
in the second reaction will be more
visible then first reaction and we have
seen that zinc has been easy to become
del plus 2 not dead in plus 2 Zn Tynan
right so we compare hydrogen and zinc so
in that case a negative potential of
this indicates that H+ ions gets reduced
more easily than Gellin plus joins so
not you see if you compare you have X
plus ions we have Cu 2 plus ion we have
genital Plaza so with these two values
we have seen that Cu 2 plus ions get
reduced more easily then H+ ions and H+
ions introduce more easily then zinc
plus ions
okay and this is something which you can
easily find using standard electrode
potential correct now let's find as I
told we told you we found the EMF of the
Daniell cell right then yourself nothing
but my analyst from zinc which identity
plus and Mike cathode is you 2 plus 2
copper I am doing both are 1 1 because
the molarity of the electrolytes matter
for this e cell will be what
P not sell as a standard balloon not
right - ki not left right right - left
what is right right as my knot off Cu 2
plus 2 cu - he left is nothing but
reduction at right Jaden 2 + 2 J then
please note it is not genuine - here n 2
plus this n 2 plus together both case I
am writing the reduction values so Cu 2
plus 2 cu we just found the value was
point 3 point 1 and then 2 plus 2 n we
just found the value was minus 0.76 volt
so we solve this you get 1 point 1 and
that's how you get 1 find one would come
it so if you see the standard electrode
potential at 219 is given for most of
the reactions and please know list an
electrode place is nothing but standard
reduction potential electrode tension is
nothing but reduction rate as per if you
see if we stay from 0 to minus 1 this
reduction happening cobalt plus 3 2 + 2
reduction happening you take anything au
+ 3 - 0 reduction happening you take
anything BR 0 2 minus 1 reduction
happening
you take copper copper plus 2 - copper
production happening 0.34 volt the one
we calculate right you see the lead pv +
2 - 0 production happening now all these
reaction you'll see reduction happening
all this thing reduction so this is the
reduced form it is the reduced form
right L + 3 - al reduction happening
calcium 2 plus 2 calcium reduction
happening all place you see reduction
happening right now you see
the reduction potential of f2 to
fluorine is 2.8 7 that means this
reaction is more feasible right as
compared to Mara again here also for us
the hydrogen is the base that is 0
actually this value is 4 point 4 the
actual value but it is assumed to be 0
correct this is all based compared to
hydrogen now I will show you how to read
this one child eyes and it is a very
very important chart I get login from
this see in the standard electrode
potential of electrode is pause
difference at the least keys right I'll
take gold you know gold is not reactive
that's something you know right this is
a stable form this is a stable gold
so the standard electrode potential is
positive that means it's reduced form is
more stable this this if you see here
all positive that means these are more
stable why if it is positive that means
the reaction is possible right in the
reaction is possible that means the
reduced one will more stable as compared
to hydrogen as compared to hydrogen gas
because I am talking about hydrogen
gases are potentially now again if the
electrode potential of the electrode is
negative example in this case that means
it's that means the hydrogen gas is more
stable than it's reduced form so the
standard electrode potential is negative
for example in this case that means it's
reduced that means the hydrogen gas is
more stable than instead of strong see I
am talking only with a reduced form so
that means in this case this is more
stable and it is listed as compared to
hydrogen gas
right because important with the
reaction I am talking about the product
these are my product so in this is
positive that means it is favorable to
get this
product that means the product is more
steeper than hydrogen if it is negative
that means it is not favorable to get
the product right that means the
hydrogen gas is more stable than this so
this is less stable this is more stable
than matchness
hope you understand this is one part
right so if the electrode potential is
positive that means the reaction is more
favorable and since electrode protection
is nothing but the reduction potential
that means the reduced form that if the
product is more stable than hydrogen gas
if this is negative that means the
reduced form that is my product is less
stable than hydrogen gas right and
standard electrode potential is highest
for learning that mean this is very very
stable right
that means fluorine gas has a high
tendency to lose electron and becomes F
minus I this is that - and we have seen
that all this chlorine fluorine bromine
they have tendency to reduce later on
well once they gain electron one the
gain electron they become more stable
right f2 plus two electron gives - this
is very very stable since they reduce
themselves they are very good oxidizing
each other right they are good slightly
because since they are getting reduced
they will oxidize something else so they
are very very strong oxidizing it
reverses to focus there will be very
weak oxidizing it or very weak reducing
eternia right same thing if you see
lithium has the lowest electrode
potential minus 3 that mean this is not
even favourable this is more stable li +
is more stable correct now if you talk
about this this was a very strong
oxidizing in they have seen because it
has put fluorine wants to become f- so
that means if you go up the oxidizing
capacity increase
Nolan has a very good story oxidizing in
it here also if you go down the reducing
agent caps in regards lithium plus is a
very strong reducing agent because
lithium plus wants to become lethal
sorry it is negative this reaction is
not favorable
so this Li plus to Li he is negative so
this reaction is not favorable the
favorable reaction will be LA to la plus
correct why why this is not available
because this is negative so this is
favorable reaction that means lithium
wants to become lithium plus lithium is
a very lithium oxidase very easily
that means lithium is a good lady you
seeing a gentle alright
lithium is a good reducing agent this is
a good lithium to play this game down
good good reduce correct okay another on
time you say so reducing agent
capability increase on the product side
and the reactant side the moment you go
up the oxidizing agent capable CD
increase and please note here copper two
plus two copper is a different value
copper one plus two copper the different
value right you don't think that copper
copper two plus Oh copper three plus of
copper two plus to cover will have same
values right all have little Bala see a
copper two plus gives copper II is 0.34
volt cordless gives copper is 0.5 that
means this reaction is more favorable
than this reaction copper 1 plus
reaction won't be driven copper two-plus
reaction both are getting reduced to
call because it has more key map now we
will see what are the users of the
chemical cells first as it is used
determine the pH of the solution we will
see using Nernst equation you can
actually find the pH of the solution
using email it is also used to find
solubility product will see some
numericals on this it'll also it is also
used to find equilibrium constant here
also we will see some numerical on this
it is also used to find other
thermodynamic property and it is also
used potentiometric titrations these are
the various uses of electrochemical
cells apart from the fact that these
chemical cells are used to produce
electricity that is the main use right
produce electricity and that helps our
laptops mobile cameras inverters they
run on these batteries and they are they
both electrical results
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