chemical kinetics.pdf

class 12 chemistry chapter 4 short notes revision ntes

1. Electrochemistry
30
Minutes
Revision
ByBharatPanchal

2. ONE
SHOT
t
SHORTNOTES
PoY.O
t
ExemplarMCO

3. &Electrochemistry3
Electrolyte:
Thosesubstancewhich
dissociateintoone
in
theiraqueoussold
on
passingelectricity
are
known
as
electrolyte.e.gNace,
keNon-Electrolyte:
Thosesubstancewhich
doesn'tdissociate
into
ions
in
their
aqueoussolution
on
passingelectricity
isknown
as
non-electrolyte
egsugar,Urea,Glucose.
whichdissociatecompletelywhichdissociatepartially
intoions. intoions.
e.gHU,HNOs,HaSOAetc.
e.gNHIOH,Calotc,
CHgCOOHetc.

4. CONDUCTORS
MetallicConductors
Electrolyticconductors
·
flowofelectricityis
duetotheflowof
electricityis
due
to
flowof
eo
theflowofion
·
Alsoknownas
electronic
·
Alsoknownas
ionic
conductors.conductors.
·
flowof
electricity
takesplace
·
flowofelectricitytakesplace
withoutthedecompositionofby
the
decompositionof
substance substance.
·
Theelectricalconductiondecreases.Theelectricalconductionincreases
with
increase
oftemp.
with
increase
of
temperaterestr
becauseincrease
oftemp,
increases
whichproducehinderance
in
theflow
ofelectrons
interionicattraction
·
low
as
well
as
High
·
Onlylow
voltage
ofcurrent
voltageofcurrent
can
pass
can
bass
throughelectrolytic
throughmetallicconductorsconductor
e.g.
re.Al,Agetc. e.g
Nax,
Naotetc.

5. ·
FactorsInfluencingElectrolyticConduction:
-NatureofElectrolyte:
larger
the
no.
ofions,
more
is
conductance
->
Natureofsolvent:
The
electrolytes
ionizein
waterbutnot
in
organic
solventslikebenzenebecausewater
in
polarwhereas
beuzene
isnon-polar.So,electrolyticconductance
increasein
polarsolvents.
-
solute-solventattractions/solvation
or
Hydration:
larger
thesolvationofions,lesser
isconductance
-Temperature:
Asthetemp.
increases,
theconductancealso
increases
because
the
dissociation
ofelectrolyteincreases.
So,numberofions
as
well
as
the
speed
ofionsincreases
->
Dilution:
Asdilution
increases,
thenumberofionsof
a
weak
electrolyte
as
well
as
theirspeedincreases
and
so
conductancealsoincreases
8

6. 9.Whatis
cell?
Am.It
is
a
devicewhichusedtoconvert
one
formofenergy
-
into
anotherform
ofenergy.
ELECTROCHEMICALCELL ELECTROLYTIC
CELLLOAN PANIC

7. =SaltBridgeitsfunctions:
a
U-shapedglasstube
containing
concentratedsonof
aninertelectrolyte
like
KCIKNO3
K250+inagar-agar
form
whose
one
endis
dipped
in
one
beaker
andandend
isdippedin
anotherbeaker.
function
-
i)Preventthepassageof
one
electrolyteinto
another
ii)Itcomplete
the
inner
cell
circuit.
ii)It
maintains
theelectrical
neutrilityofsoil
in
bothhalf
cells.
iv)usedtoconnectboththebeakers.
-
I

8. ElectrochemicalCell/Galvanic
Cell
/
Voltaic(ell:-
It
is
usedto
convert
chemicalenergyinto
electricalenergy.
.
we
taketwobeakers
·
InIstbeaker
we
take
In
roddippedinInsofsol
·
In
Indbeaker
we
take
Cnroddippedincuso+soll
·
Salt
Bridgeisusedtoconnect
boththebeaker
·
oxidationtakesplaceat
In
Godin
Istbeaker
·
Reductiontakesplaceatcu
·
OxidationhalfRxU
rodinandbeaker.
In
+2n+2ee
LO
AN
·
Reductionhalf
Rxn
Cuf++2e0-ce left
o
Anode
Negativere
OverallyIn+cu
->
Int+
G OxidationUI
2

9. ElectrodePotential,
the
tendency
of
an
electrodeto
either
lose
or
game
to
when
itis
placedinits
own
solution.
S
fo
t
OxidationPolential ReductionPotential
The
tendencyof
an
electrode
The
tendency
of
an
electrode
tolose
ee &
togam
ee
STANDARDHYDROGENELECTRODECS.U.E)
Devicewhich
is
usedto
Calculatestandardelectrode
us Potential
ofanyelectrode.
->
It
canactas
bothoxidation
as
well
as
ReductionPotential
A
sAnode
-
He->2HT+
2e0
Ascathode
-
&H+
+2e0-Ha.

10. ElectrochemicalSeries
Arrangement
of
variouselectrodes
in
the
increasing
orderofstandardreductionpotential.
CHI
Li
-
withium
-
3.05V
ca-calcium
-
2.87Vself
a
A1-Aluminium-1.66V
2-
Zinc
-
0.76V
th fe
-
Iron
-
0.44U
set Ni
-
Nickel
-
0.25V
rico
Ob-lead
-
0.13V
H
-
Hydrogen
0.OOV
Cut
to
Cr
->
copper
+
0.3AVAge
5)
exer
t0.SOV863453
By
T
Bromine
+1.O8V37ACc
Ac-Gold
↑
1.SOV

11. Application
1)ComparisonofRelative
ReducingPower
or
oxidisingPower
2)
Predicting
the
feasibility
or
spontaneityof
a
RedoxReaction
3)
Predictingwhether
a
metalwillreactwithdilute
mineralacidsandwillevolveHydrogengas
or
Not.
2)
Activity
or
reactivity
ofmetals.
3)CalculationoftheEMEof
a
cell.
E.
M.F
=
Ecel:Ep-Ec
=
Ecathode-EoAnode
-
EReduction
-
Foxidation

12. NewustEq,"
DependenceofEMF
on
concentrationofelectrolyte
andtemperature
Nerusteq,"
forhalf
cellRx
Mn++hee->M/s
(99)
FM
=
EMFenMsrea
EM:
electrodepotentialofmetal
under
givencondition
EM:
electrodepotential&
metalunderstandardcondition
R:gasconstant
=
8.3145K-mol-
T:TempinKelvin
F:Faraday
constant(96500(mol
1)
n
=
n0.6
to
loss
or
gain
inreaction
EM:
Em-059llyn+y
Em
=
Em
-
0591lg
n
+3

13. Forcell:-aA+bBEcC+dD
Excell:
Ecell-alligactcl
te
of
Ecell:
Fcell-oral
logoa
=>
Ecell-0591lg
Oc equilibrium
where
is
concentration
quotient,
constant
At
equilibriumEcele:
0
andQc=KcEiel=0591lgkc
Cat
298K)
standardMaximum
Gibbs
or
workdone
A4=-nfEel
free
energy
bycell

14. Calculatethe
eatoffollowingcellat298K:
Mg/Mg*
(0.001M)
//CuS(0,000/M)/Cu
EmgCtMg=-2.37V
En+/(u
=
0.3AV
Am
Etell:Ep-Ec
>
0.36-(-2.37)
=
2.71V
Ecell:
Eiell-591
legoxinin
=
9.71-591lig
agesare
=
2.71-591
log
of
a
=
2.71-0.02955=52.68V

15. =
CalculatestandardGibbsfreeenergychangefor
the
givenreaction:2n+Cult->Inet+Cu
AnDC:=-UFEcel GivenEell:
Hop
=
-
2X96500X1.10
=-2123005
mol=-212.3K5molt

16. ConductanceofElectrolyticSolutions
·
Resistance:
It
the
obstructiontotheflowofelectric
through current
It
isdirectly
proportheconductor.Youroth
(l)andinversely
proportionalto
area
ofcrossection(A)
RC
or
R
=
s
A
specificResistance
or
Resistivity.
UnitofResistance
=
ohm(l)
Unitof
Resistivity
=
ohmmetre
(2m)
·
conductance:
the
inverse
ofresistance
a
=
=
A
=
k*
Unitofconductance
is
ohnt
or
who
or
lt
or
siemens
CONDUCTIVITY:
The
inverseof
resistivityis
calledconductivity
especificconductance)
unit:ohntcm-a=k*
whenArkana1=LiM
G
=
15
conductivityof
a
materialisits
conductance
whenitissomlong
andits
area
of
cross
sectionisLama.

17. ·
MOLARCONDUCTIVITY:
It
is
the
conductivityofallthe
ions
producedbydissolvinga
moleof
an
electrolyteinsoll
It
isdenotedbyam
am
=
kXVoram
=
15x00
=
kX
Units:ohm"cmmoltor
s
comemolt
Molarity.k
=
ax
Note
R=
1"Theis
calledcell
constantdenoted
by
qx==RK
am
=
k-X
8.Discussthevariationof
conductivity
andmolar
conductivity
withconcentration
(NCERT
Am
In
case
ofstrongelectrolytes
themolar
conductivity
Amydilubort
coneto
increasesslightly
with
dilution,
as
mobilityofionsincrease
In
case
ofweak
electrolates
the
degree
14dilbortconc.k
ofionisationincreaseswithdilutiontherefore,
there
is
a
largeincreaseinmolarconductivity
withdilution.
conductivltyisconductancebetweentwo
oppositefacesof
one
centimetrecube.On
dilution,
no.
of
ionspercm3decreasesthereforeconductivity
decreases
on
dilution
CHyCOOH
xm
=
limiting
molarconductivity
when
concentrationapproaches
zero,themolar
conductive
presen
KC
conductivity.

18. KOHLRAUSCHLANN:
-
Limiting
molar
conductivity
of
anelectrolyteisthe
sum
ofindividual
contributionof
anionandcationofelectrolyte.
AAB
=
AAT
+AmB-ImNU=Natida
MAT:
limitingmolar
conductivityofcation.
NinB:limiting
molarconductivityofAnion.
Applications:
-
is
calculationoflimitingmolar
conductivityof
weak
electrolyte.
is
calculationoftheDegreeofDissociation
-DegreeofDissociation(c)
am-
Molarconductivityat
anyprote
CONC.C.
iii)Calculationofdissociationconstantofweakelectrolyte:
2
=
concentrationDissociationConstant(k):
<C
c
=
DegreeofDissociation

19. ·
suggest
a
waytodetermine
the
airvalueofwater.
Al
AimCHO)
=
SmH+
+
dm
OH
-
-
we
find
out
amcrce),amcNaon)
andamchasesthen
ACHO)
=
AmCHCD)
+am(NaOH)
-
am(Nac
8.
The
conductivityof
0.comsolutiono
keat
298Ki
0.0218s(.m.Calculateitsmolar
conductivity.
(NCERE)
An
am:
xloo.o8x1000
=
124,cmemo
to
⑨.AimforNall,
HCand
CHylooNa
are
126.4,
425.9and
910scdmol"respectivelyCalculateiforCH.coon.
An.AiNaU:jwNat+juC=
186.4sc.mMol-O
-
amHU:dint
+
did:425.9
scm-mol-
-
AmCHyCOONa=diCHyCOO-+dmiNat:
91.0Sc.MCmol"-O
we
havetocalculateinCHCOOM:AmCH100+nmHt
operating@t@-0
390.5
semol

20. Faraday'sLawofElectrolysis:
firstlaw:
Themass
ofsubstance
deposit
or
liberated
at
any
electrode
during
electrolysis
isdirectly
probortionaltotheamountofcharge
passed.
MathematicallyWXO
E:
I:
B/t]
# WXIXt [IXt
=
0]
w
=
zXIXt
wemass
ofsubstancedeposit(liberate
2-
electrochemicalequivalent
z
=
g56500
=
armasa
It
currentto
time
⑨what
doyou
mean
byFaradayConstant?
Am.Chargeof
one
moleof
ee
F
=
6.022x1093
x1.6x10
-
19=96487(molt
↑
96500(molt

21. secondlaw:
-
whensame
amountofelectricitypassedthrough
two
differentelectrolyteconnectedinseries,amount
ofsubstancedepositedatelectrodesisdirectly
proportional
totheirequivalentweight.
AModntG
Agdeposit
c.
9AONE
9.
Asolutionofcusor
electrolysed
for
20
minuteswith
a
current
of
1.5ampereswhatthe
mass
ofcopper
depositedatcathode RT
An
ACC.toRxCuet
+200
->
Cu
w
=
2XIXE
=
MabyIXt=5X.5Xo
10.2938g

22. BATTERIES
Thesearesource
ofelectricalenergy
which
mayhave
oneormore
cellsconnected
inseries
C
Goodqualitybatteryshould
be
light,compactand
itsvoltageshouldnotvaryduring
its
use.
PRIMARYBATTERIES
the
reaction
occur
only
once
andafter
useover
a
periodof
time,
batterybecomesdeadandcan'tbe
reusedagain.
DRYCELLORLECLANCHECELL
(+)
Terminal
Thiscell
consist
asInGodact
as
anode
andcathode
is
carbonrod
whichis
surroundedbybowderedMade
in
-2n2+2e0
AtCathode-
>MuOz
+C
MnOs+2NHy
+2e0>MucOs+2NHstHO
·

23. MERCURY
CELL
It
consist
zinc-mercuryamalgam
as
Anode.
-Anodecay
incing.The
cathode
is
a
paste
mercuric
oxide
(Ngo)
separaort
can
CAmalgamandCarbonpowder.
The
electrolyteconsistof
a
mixturekou
andno
>Cathode(Hgo)AtAlode
In
+20n
->
2n0+H0+900
i Atcathode
HgOtHgO+Re0
->
Hg
+
2OU-
2n
+HgO->ZnOtHg
#Thepotential
ofamercury
cell
approximately
1.35V.
It
remains
constant
as
in
the
overallcellreaction
no
tons
are
involvedinsolution.
Thus
itlastslonger.
UsesofMercurycell
It
issuitableforlowcurrent
devices
likewatches,hearingaids,toysetc.

24. secondaryBatteries
A
secondarycellafter
usecanbe
recharged
bypassing
current
itinoppositedirectionso
thatit
can
be
used
again.
Agoodsecondarycell
can
undergo
a
large
no.
Idischarging
and
charging
cycles.
egleadstorageBattery,
Nickel-cadmiumbattery,
u-You
battery
LEAD-STORAGEBATTERY:
-
it
consist
of
a
leadanode
and
leadoxidecathode.A38%
not
⑦ solution
of
sulphuric
acidacts
I
I
Cathode
aselectrolyte.Eachcell
give
cellissufficient
to
give
EEEEEEEEEEEEEEEEEEE
thevoltage24
so
this
thevoltage
of121.These
voltaiccells
are
separated
bythinfibre
glasssheet.
DuringDischarging,
thecellreactions
are

25. DuringDischarging,
thecellreactions
are
ATANODE
Pb+SOn?
->p650x+Cee
ATCATUODE
PbOc+SO,+AUT+Ce0
->
PbSOrtCHO
TheOverallcellRX:
Pb+PbOc+2HaSOc
->
2P650
++
CHO
Duringcharging,
currentispassedthroughthe
terminal
fromexternal
source.The
reactions
are
reversed
Uses
=it
iscommonlyused
inautomobiles,power
↑
uverters

26. FUELCELL:-
chemical
energyfromcombustion
of
fuels
likehydrogen,methaneand
methanolisconverted
into
electrical
energy
-
It
ishighlyefficient(70%)
HzO methodwhen
compared
tothe
Cathode
efficiencyofthermalbowerplant
-side
productis
waterwhich
doesn't
cause
pollution.
are
bubbledthroughporouscarbon
trodoEEEEEEEEEEE
Inter
⑲
Inthe
cell,hydrogenandoxygen
(40%)
electrodesintoaqueoussodium
hydroxide
solution.
Finelydivided
O2platinum
or
balladium
acts
as
a
catalyst·
*
Itwasusedforprovidingelectricalpower
A
pollospace
programme.
Thewatervapourswere
producedcondensedandaddedtothe
drinking
watersupplyforastronauts
Atcathode
8+C
H0+100
->
you-
AtAnode
21+
you-->
HHO+
fee
overall
cellRxU
interna

28. thank
You