Conductometry

Its is very helpfull for students of graduation .
it contains basics of conductometry.

1. Prepared By
Asmita S. Satao
M.Sc. Sem-2 (Analytical Chemistry)
Fergusson College, Pune (MH)
CONDUCTOMETRY

2. Synopsis
•Introduction to Conductance
•Introduction to Conductometry
•Historical Background
•Principle of Conductomerty
•Instrumentation
•Instrumentation: Current Source
•Instrumentation: Conductivity Meter
•Instrumentation: Conductivity Cell
•Instrumentation: Electrode
•Working of Conductometric Device
•Application of Conductometry
•Advantages of Condtuctometry
•Disadvantages of Conductometry

3. Introduction to Conductance
•Theconductanceistheflowofelectricitythrough
electrolyticsolutionduetomigrationofionsbyapplying
potentialdifferencebetweentwoelectrode.
•Cathode(-vecharged)willattractscations(+ve).
•Anode(+vecharged)willattractsanions(-ve).
•Conductance(G)isinverselyproportionaltotheresistance
(R).
G=1/R
•Unitofconductanceissiemens/meter(S/m).

4. Introduction to Conductometry
•Themeasurementofelectricalconductivityofsolution
duringchemicalreactioniscalledasconductometry.
•Itisdeterminationofqualitymaterialpresentinmixture
bymeasurementofitseffectonelectricalconductivityof
mixture.
•Conductometryisoftenappliedtodeterminethetotal
conductanceofsolutionortoanalyzetheendpointof
titrationthatincludeions.

5. Historical Background
•Measurementofconductancebeganasearlyasthe18
th
century,whenAndreasBaumgartnernoticedthatsalts
andmineralwatersfromthetownBadGasteininAustria
conductedelectricity.
•Firsttimeconductometryisusedintheyearof1776for
thedeterminationofpurityofwater.
•FriedrichKohlraushfurtherdevelopedconductometryin
1860.
•Conductometrywasfirstimprovewiththedevelopment
oftheglasselectrodein1909.

6. Principle of Conductomerty
•Conductometryisbasedontheprincipleof
determinationofchangeinconductivity.
•Changeinconductanceisduetoreplacementofions
witheachother.
•Ionicconductivityisdifferentfordifferentions.
•Forexample,IfwecarryoutreactioninbetweenHCL
andNaOHtheninthisreactionH
+
ionsreplacedbyNa
+
ionsthenconductivitydecreasebecauseconductivityof
H
+
ishigherthanNa
+
.
•Movementofionsismainlydependuponthe
concentrationofions.

7. Instrumentation
1)Digital Display
2)Calibrator.
3)Power switch.
4)Burette.
5)Titrant.
6)Anode.
7)Cathode.
8)Magnetic Stirrer.

8. Instrumentation: Current Source
•Alternativecurrent(AC)isusedassource.
•HighfrequencyACgeneratorisemployed.
•Electricalpotentialisapplied,ionswillbetransferredand
intimatelyconductancetakesplace.
•DCcurrentisnotusedbecauseelectrodebecome
polarizedleadingtohighcellresistance.

9. Instrumentation: Conductivity Meter
•Conductivitymetermainlyconsistofthreecomponents.
1).Digitaldisplay.:-
1.Itdisplaytheconductance.
2.ConductancecanbemeasuredinmicroSiemensandmiliSiemens
dependingupontheconductivityofions.
2).Calibrator.:-
1.BeforewemeasuretheconductancewehavetoCalibratethe
instrument.
2.Calibrationmethodisgivenoninstrument.
3).Powerswitch.:-Toturnon/offtheinstrumentPowerswitchisused.

10. Instrumentation: Conductivity Cell
•ItismadeupofQuartzorPyrex.
•Inconductivitycelltherearethreetypesofcells.
1)Lowconcentrationmeasurement.
1.Itcontainsajarinwhichtwoelectrodesaredippedinsolution.
2.Electrodemadeupofplatinum.
2)Forprecipitatetypeofreaction.
1.Precipitatetypeofconductometrictitrationcanbecarriedout
satisfactorilyiftheensuringreactionproductissparinglysoluble
orhavingstablecomplex.
2.Itcontainsmagneticstirrer.Duetomagneticstirrerprecipitate
doesnotstickonsurfaceofelectrodeandyougetproperreading.

11. Instrumentation: Conductivity Cell
3) Dipped type
Asitisconvenienttodippedinsolutionduetoits
compressedsized.
(A) (B) (C)

12. Instrumentation: Electrode
•MadeupofPlatinum(Pt).
•Surfaceareaofelectrodeis1cm
2
.
•Distancebetweentwoelectrodeis1cm.
•Electrodearecoatedwithplatinumblacktoavoid
polarizationandtoincreasesurfacearea.

13. Working
•FirstlyCalibratetheinstrument.
•Aburettemustbefilledwiththebaseandtheinitialvolume
mustbenoted.
•Aconductivitycellmustbeinsertedintothedilutedacid
solutioninsuchawaythatboththeelectrodesarecompletely
immersed.
•Theconductivitycellcanbeconnectedtoadigital
conductometerinordertoobtaininitialreading
•Thenthebaseaddeddropwiseintotheacidsolution.The
volumeofbaseaddedmustbenotedalongwiththe
correspondingchangeintheconductance.

14. Continue. . .
•Asharpincreaseinconductanceofthesolutionimplies
thatendpointhasbeenreached.
•Theobservedvaluemustbenowplottedgraphically.
•Theequivalencepointcanbeobtainedfromthepoint
ofinsertionbetweenthetwolines.

15. Applications
•Tocheckwaterpollutioninlake,riversandotherwater
reservoir.
•Itisalsousedtocheckalkalinityoffreshwater.
•Salinityofseawatercanbecheckedbythismethod.
•Itisalsousedtotraceantibiotics.
•Usedfortracingmicroorganismsinfoodmicrobiology.
•Purityofdistilledwatercanbedetermined.
•Tochecksolubilityofsparinglysolublesalts.

16. Advantages
•Themeasurementprocessofconductivityisquite
simple.
•Provideaccurateresultswithminimumerrors.
•Bygraphendpointcanbedetermined.
•Suitablefortheanalysisifweakbases,weakacids,
combinationofstrongandweakacids.
•Thismethodisalsosuitableforturbidsolution.

17. Disadvantages
•Onlyfewspecificredoxtitrationcanbedonewiththe
helpofthisprocess.Thisisbecauseofconductivityof
thesolutionismaskedbyrelativelyhighhydroniumion
concentration.
•Theaccuracyofcomductometrictitrationislowwhen
conversionoftheelectrolytesarehigh,makingthe
titrationprocessunsatisfactory.

18. Thank You !!!