.
Applications of Conductivity Measurements
Some of the important
applications
of conductivity measurements are as follows:
Determination of degree of Dissociation
The degree of disociation of a weak
electrolyte is determined by the application of expression:
a
m
Where A is the molar conductance of the solution and can be obtained experimentally ^m is
the molar conductance at infinite dilution and can be found
from the literature. The method may be
illustrated with special reference to the determination of the dissociation of
phosphoric acid. Consider
phosphoric acid. ionizing as a monobasic acid in to H and HsPO4 ions,
at 25 °C.
A (PO) =A (HC)+ (Nal12PO4) - Am (NaCl)
378.3 70:0 109.0
339.3
acid is 96.5 Scmmol" and the approximate
The measured value of a,, for 0.1M phosophorie
is approximately
dissociation is 96.5/339.3 i.c., 0.285 and
the concentration of the ions
degree ot
0.0285 M.
Determination of Solubility Product of a Sparingly Soluble Salt
1 is
such as AgCl, BaSO4, PbSO4
dissociate in a simple manner, it
If aslightly soluble electrolyte
measurements.
possible to determine the solubility of such salts by conductance
soluble salt and *" is the specific
If *s is the solubility in mole/liter, of a sparingly
relation
conductance 'A is given by the
conductance of the saturated solution, then its molar
k
1000
i.e. s = 1000
At infinite dilution,
k
S= 1000
of a sparingly soluble salt may be
The method for the determination of solubility products
of silver chloride in water at 25°C. First the salt is
explained by taking the example of solubility is suspended
water to remove any soluble impurities. After that it
repeatedly washed with conductivity minute quantity of salt will pass in solution
in conductivity water, warm and cooled to 25°C. A very
conductance of the solution and water used in the preparation of
and the rest will settle down. The
the conductivity cell in the thermostat maintained at
solution is determined in the usual way by placing
25c.
The value of A, for AgCl is given by
Cl'= 61.92 + 76.34 138.3 S cm mol'at 25°c.
(AgCI) A Ag"+ A
=
=
The specific conductance of a saturated solution of AgCl in water is 3.41l x 10° S cm' at 25°C
and if 1.60x 10 is deducted for the conductance of the water, the value of k is 1.81 x 10° ohm' cm
-
Hence solubility of AgCl may be determined by putting the values in eq. (71).
S= 1000
m
= 1000 x 1.81 x 10/ 138.3
TONIC PRODOCT OF AATER
The dissociaüon
Wats a weaK ole colyle
Onsiode
a
watu Can be
quualibuium of
94120 H30 tOH
a ction
o lauw ofmash
ACcosdun9
Ke
H:0]
n excass
Since wall as a Solvent always
due t
it dis sotiakion in
in Lon Ce nthation
and change centhatton as8 umed to be
ence wal ton
negligi ble
CDnstant.
oH) k
Kea H0 Hso")
as 1he
Loric PAodlu ut
Lonic Phoduct
lart ky is Calleol
The Lons
the phoduct o
Phoduct
and i value given by
wateu CoH )ns
CoH-)ton
of
hydsonium (H30
and hyd so xide
hydxocide
Con
centations oo
modm6
At 298 k, K. 1 x10
n duuCtometeuc itations -
(ondu ctomutnic measument 8 ue
1
onenuontu &mployot
to ne he tnd port1 o6
acicl -bae and 0 me tbattoJn such t battons
vauetion o tu tquivalent Londuttanu by h
addilton of tibhant imasmed.
In tonductometiit
advantage taken on 1he {at that
ton ductivty of a SotutHon ofLdependant upon
TuUnboA Ofons and theik tonduu fanu.
fhe
The addtton ef one alectolyte
phoduting no appiCi able
the
Change in volum wtl al the onductanu of
To me onie eacHon
he Solutton accoading
no. ioniu AL action taku place Then the
condu ctHvity also dvesnof Change and
tn
RRation ocCuns, thange Conductvity
oni
OCCuus.
Pg.NO o
Sthong acid vs StAong Base
tOnsi du fhe tibaton o StAong ocid,
Hd wh a shong baso Quch u 8odium
Hydxonide (NaoH)
The aid taken in a
Conduuctivity and alkale in a buctte
The tonduuctane et Hc due
he pAsCnd cf hyduogon on chlostde tons
AS the alkali i added 9Aadually the hydsogen
LDns 0t plaud by glow movlng sodtum ions
H() t cd (aap)] +
LNaia) tOH la4)
Na+
ta4) 4)+H0(1)
AS godium Hydhortdt addecd thL
AemLoved a sigkt4 jonusod
wate
Thulo, the Lonductanu w
deuase
At neuthlizaton
Point Thu Sotutton
(ontains Ng* and u fon wtl
have Qonslduuably low ontae tanu.
Any 9ubsequent addlition t e alkal"|
W sult tn fast moving hydsoay! lont,hesu
The tondu ctane will in
uuase
Minimum
Teaching a Ctain Ceutain valuu
Hd +NaOH Nat tcl tH
Bf Equl valunu
Doiv
Vu
e MADH addud a)
Gaaph fo
HCI vs Na0H lonductanu.
weak acid vg shong Base:
(ongi du a weak aud Suth as
acuttc ocid (has euy low tondut tanu )is ithatd
againsk a sthong base Such as lolium hydao«ide
salt Such as Sodlum aetate, i
(hign tonoed
o NLA CH2cooH +Naonlaa)CH3Co6 tNa tH20
TnSpitt f tommon lon allett, Nuthal galt
1h
which fOsmtd dusing ut paut
zatfon ot
tithaton tnds to Suppo 8S tu lon
the Lonductante fn uajek,
CH3C00H sll pUsent,
A end point when acid à tomplut
neuthal ged usthu additlon alkolin Pnioduc
th eness of fast movng hydroryl Tors, eo
tonductanu ntuases
4MValenu to'nt
Volune NaoH addrd
StA ong acid Vs WaK BOse
7we tittati gtsong acid ik Hd
wi1h aweak baie Such Qu gmmoni um hyelonfau
weak base to a gthong actd
Then additHon o
Cause the Conductanw dease tet
as HTons a Aaplaced by 8lo moving
am moniu tons NHg4
Hd +N,OHNHytl tH20
At neutalii ation of the aid,
fuate addition weakly ionised NHyOH
will Case ho appudalu change In hu tonduttan
LVal ene
Doint
Volwm Hy dil aed dud trul)
Mxtu awMaK and astAOg acjd Pa-ND: 14
Vs Sthong base.
when o minlu o weak and sthon
a cid like atetic acid acjd
qnd hyoo chlosit
tibatad against a 8rAong buue ire NaoH, a Cutv
eThe type shoton n tw igu below ts obtainud
In pesenu of a sthong aid foni ation of a weak
acid Is upped Clue Common ion slfeck.
So gMong acid nuts alised.
rs
fo llo wed by a weak acid. Theuto the
ALt point nts Sectton iapotnt 4 4 to tVe
nautkalzaten a stng ac and Point c Lujeu
t Th (onmple to neudsalnation an acid mintuue.
Velum Nao addud
86Stondand Haokroqon Elachnade
A s the psuimcey stounolceol
Small
olcttnoclo t Censists ef o
toatad wtth
plalnum
Platinum toil
hydsgen, A Plalnum titez
do a b a b
alectouoola
ano
Qnd
ielelas do he
s
tube Thus
Jcrbal thoieugh a glass
CotCuut
hmaRes Cntct tith e 1he
ope3ontation
Pt H(1atm)HiM ov
Ha gas a t
ct m
>ilass hooe
P toloetrok
Covoool uithHa
IM Selutionef Hat
5c
huplroycn olocteelo
SHE S tondosrod
Gut
The p t o l (olaool hy an
hos inlet deor hdiogsn
an
hich
Gless uhs the bettem
anumbei hes at
and Th
he eecape
xCesS a 9as
o un a olilute
beluten
e l e c t u o o l e us placeo
heqlam
oue Containing
an punhyelicgen
ito1.
yuvabnt a atiel Rer
tfhocugh t
.
s bubblod
loatm pic2eLe
at abscebool
by th
A Paot tho qes 0Bcopos
Ohyobtegon
oloctrede and OKOSS
Pt yulubsvium botnieon he
Gut Thus an
e n tho olectreolo and
abssnhodhylegen
the H Jons ih Soluton takos plate
Elcdheus
Sing alettodes
A Single elethode is tomposed a
e etaie tondu lontact wlth an slem lyie
,
in
etal,
be a
LOTLcu cTo. An lotuo tonduutoa may
oalla
a abSobed on metal oA a metal
a
Spauingly Soluble Salt and an
oith SolutHon
l e t o lytx
aledolyta Londuclot may
be
OA sed sal.
1.Met- Metal 1on eleciode
ele duode tonststt chb
This
ape o an
ions.
a
Solution
of I oon
in
a metal Aod dipped
dipped In zine lfau Solution
-9) zine ked fepugentid
as,
be
eleiode Sealton may
The
MAa) tne Mls)
behave asa Mab vd positlve
Imetal
The
ShiH lowands Aight.
fhen equai bsium will
M fon n Sot s du uese. 1| tu
tontenuation
negaHve ions th 2auali bAium
Mutal beha ves asa
Contentaton M lonu in sr
ynusase
a Tn soluble metal sald elechodumetal and
Lonsist a
These letaodes
Th Sau metal
Salt o*
S a m e
Spaing ly Solub haying
Th
uble
dlpPping na Selution_f
a
anion
of tis ypo
An impoltant ele ctuode
il tonsistu o metuy
the Calomel eletspde. chloide
uuou
soluble
salt, solid me
Spauingly a tomno
pettasium
chlosiele having hlosde,
aSoutHon
salt
muscuus Chlok
Solubls
fon (el-) wlth SPaulngly Hg
cd,)
ug:
be upu sentud as
The olechode may
silva -Silvet
chlotide- Hy dro
Kel (sol)
6theu example:
alectode
chlonit Acid
3. Gtas
eledhooluL
a gaues9
These
electudu onsibt
Tough soluionu theà i
bubblin4
tonHinuously
pussuL. In this ype o
valu gas
at a stuady non meBal is tontact wlh
lechodu, a gaueous t gascs ane non
the
ele ieity , an inuk utal such as
Conductoks d
is diprd in 9erl Contain ing theiong
pt, old, gaaphit
othe gos and tw 1a4 s bubbled ovc t
Cy3enslectscole,
amples Hycuogen eletieole Orygen
chloaine &leduodle
Inut Meta Oncidation Raoducion leLodes
Th tium onidatton eduction alectodle
wod oA those le chotu Podent tal 1
hich
lone the 8ame Sues
vLloped due to Lesence of
in u dHaunt oxidaion otatu. 7his lype
Alehools consistu an intu oleduod immaed In
fhe Subs both The
a mized Sof. tontainng
when a Pt w
ozidined and wduud otms.
long
is ineted Into the Sbf cont aining fet ard Fes*
be uptesentud as.
le cthode iea cion may
Th
Fe Caa) * Fe*laa)
tho nad metal s to pick up
The gunction ol tontac-
The olo th ical
alechon and to phovicl
the electoele.
9. b)Nunst EuaHon
In 1889 NOLnst dulved a quantitatBve
elatton bet wecn The cle tbeda Potental and
the on (enthatfon mital Tong ase involved.
The maci mum wosk avalibll wm
&e veigibl chemiual PAotess is equal to the
marimum a mount o ele thital anng4
Accoding Vant Hof Iso tnesm,
AG At +RT An P
whe
AG- Change în ee anng
AG ehange in un enugs at Stardaid
ConodlHon.
R Gras Lonstant
T- TempeLaluu
P
PAoduts ton (ent kation
R-Ruactant on centsation.
This Change in
ue onug is tonvohd do
leccal ong hich iven by nEF whu
E omF aa day. The ntgatve grgn indtcats
de tuuasing duing the eaction.
Re nug4 in
A01 n E F
Aor -nEF
tne ahove 2uation,
D equaHng
nEF nE°F + RT ln
dividing by -
nF
.RT1n
E
F°-2 303 RT Log
nF
an Oxidatton Realtion:-
Cpraides 12
M- M+ne
E2.303 RT Ing M
nF
F:
F-2303 Log M"
-2303(8.314) a49) leg mn
nx 964so
F- 0:054 log M3
t.
EE o.O9 Log
n
tend tonetde Re stuetion Reacion:
M tne M
: E-2303RT og m)
M
9.303R LonF
E+-303R o [M"J
nF
