Volumetric Analysis Power Point Presenation

A detailed power point presentation introducing Volumetric Analysis

1. Introduction to
Volumetric Analysis
S.Y. B.Sc. Semester –IV
Dr. AshwiniWadegaonkar

2. 1.Introduction
2.Methodsofexpressingconcentrations
3.Primaryandsecondarystandardsolutions
4.Apparatususedandtheircalibration:burettes,micro-
burettes,volumetricpipettes,graduatedpipettes,
volumetricflask
5.Methodsofcalibration
6.Instrumental&non-instrumentalanalysis–Principles&
Types

3. Introduction
Chemicalanalysisplaysanimportantrolein
studyofcompositionorconstituentsof
substancesormaterial.
Thechemicalanalysisisbroadlydividedinto
twotypes
Qualitativeanalysis
Quantitativeanalysis

4. Thevolumetricmethodinvolvesmeasurement of
volumesofthereactingsubstances.
Theweightoftherequiredconstituentsisindirectly
obtainedbymeasuringthevolumeofasolutionof
knowncompositionrequiredtoreactwithaknown
volumeofasolutioncontaininganunknownweightof
thedesiredconstituent.
Thisisdonebyaprocessknownastitrationwhichis
dividedintofourtypesdependinguponthenatureof
thechemicalreaction.Thefourtypesare
a.Acid–baseorneutralizationmethods
b.Precipitationmethods
c.Complexometric methods
d.Oxidation–reductionmethods

5. Thequantitativeanalysisisfurtherclassifiedinto
twobranchesnamely
Volumetricanalysis
Gravimetricanalysis

6. Volumetric analysis
Volumetricanalysisisalsoknownastitrimetricanalysis.
Thereagent(thetitrant)isaddedgraduallyorstepwisetotheanalyte
fromaburette.
Thekeytoperformingasuccessfultitrimetricanalysisistorecognizethe
equivalencepointofthetitration(thepointatwhichthequantitiesofthe
tworeactingspeciesareequivalent),typicallyobserved as
acolourchange.
Ifnospontaneouscolourchangeoccursduringthetitration,asmall
amountofachemicalindicatorisaddedtotheanalytepriortothe
titration.
Chemicalindicatorsareavailablethatchangecolouratornearthe
equivalencepointofacid-base,oxidation-reduction,complexation,and
precipitationtitrations.
Thevolumeofaddedtitrantcorrespondingtotheindicatorcolourchange
istheendpointofthetitration.
Theendpointisusedasanapproximationoftheequivalencepointandis
employed,withtheknownconcentrationofthetitrant,tocalculatethe
amountorconcentrationoftheanalyte.

7. https://www.youtube.com/watch?v=Iurzrzwm9Fo
https://www.youtube.com/watch?v=d1XTOsnNlgg
https://www.youtube.com/watch?v=wRAo -M8xBHM
https://www.youtube.com/watch?v=YIYJr6WlfHA

8. Involumetricanalysis,concentrationof
substancesarefoundoutbyvolume
determination.
Theunitusedformeasurementofvolume
ofaliquidorsolutionis“litre”.
Thelitreisdefinedasthe
‘volumeoccupiedbyonekilogramofwateratthe
temperatureofitsmaximumdensity(4
o
C)andat
normalatmosphericpressure’.

9. Themillilitreisthethousandthpartofa
litre.
Thecubiccentimeter(cm
3
)isthevolume
occupiedbyacubesuchthateachedgeof
thecubeisonecentimeterinlength.
Therelationshipbetweenmillilitreand
cubiccentimeteris
1000ml=1000.028cc
Thetermmlismorecorrect

10. Theprecisionofvolumetricworkdepends
uponaccuracywithwhichvolumeof
liquidscanbemeasured.

11. Therearecertainsourcesoferrorswhich
mustbecarefullyconsidered.
◦Changesintemperaturecausechangeinthe
volumeofglassapparatusandliquids.
eg.Anordinaryglassflaskof1000mlvolume
showsanincreaseofincapacity0.025mlper
degreecentigrade.
◦Theremaybeerrorsofcalibrationofthe
apparatus
eg.thevolumemarkedontheapparatusmaynot
bethetruevolume.
•Sucherrorscanbeeliminatedonlyby
recalibratingtheapparatus

12. Methods of Expressing Concentration of
solutions
Therearemanysystemsofexpressingthe
contractionofsolutions.
Weightofsolutepresentinagivenvolumeof
solution
Molesofsolutepresentinonelitreofsolution,
calledmolarity
Gramequivalentsofsolutepresentinonelitreof
solution,callednormality
Percentageofsolutebyweightinasolutionof
knownspecificgravity

13. 1.Weight of Solute per Unit Volume of
Solution
Inpreparationofsolutionusingthissystem,a
knownweightofthesoluteisdissolvedand
dilutedtoknownvolume.
Ifaccuracyisrequired,thesoluteisweighed
andtransferredtoavolumetricflask,and
dilutedtoaknownvolume.
Theconcentrationisusuallyexpressedasgrams
ofsolutepermillilitreofsolution.
Anymultipleorfractionalpartofsuchsolution
willcontainaknownweightofsolute.

14. 2. Molarity
a.Amole:Themolecularweightexpressedingrams
ofanysubstanceiscalledasmoleorgram
moleculeofthesubstance.Forexpamle,sodium
chloridehasmolecularweight58.5gofsodium
chloridemeansonemoleofit.
b.Millimole:Themoleisverylargeunit,hencea
smallerunitwhichisonethousandthofit,known
asmillimoleisused.Thus1mole=1000
millimoles.
c.MolarSolution:Amolarsolutionisdefinedasthe
solutioncontainingonemoleofthesoluteinalitre
ofitssolution.Forexample40gofNaOHisone
litreofsolutioniscalledas1MNaOHsolution
Weight of solute in grams
Number of Moles = --------------------------------
Molecular weight of the solute

15. MolarityofSolution:Itisdefinedasthenumberof
molesofthesolutepresentinonelitreofitssolution.It
canalsobedefinedasnumberofmillimolesofasolute
presentinonemillilitreofitssolution.
Number of moles of the solute
Molarity = --------------------------------------
Volume of the solution in litre
Number of moles = Molarityx Litre
Number of millimolesof the solute
Molarity = ------------------------------------------
Volume of the solution in millilitre
Number of millimoles= Molarityx MilliLitres

16. 3. Normality
Theconcentrationofsolutioncanalsobeexpressedinterms
ofnormality.
Varioustermsinvolvedinitare-
Equivalent Weight :
Theequivalentweightofasubstance(elementor
compound)as:
“Thenumberofpartsbyweightofit,thatwillcombinewith
ordisplacedirectlyorindirectly1.008partsbyweight
ofhydrogen,8partsbyweightofoxygen,35.5partsby
weightchlorineortheequivalentpartsbyweightofanother
element”.

17. MilliequivalentWeight : It is obtained by dividing
the equivalent weight by 1000.
Gram Equivalent Weight : It is the equivalent
weight expressed in grams
Equivalentweightofasubstance=1equivalentofa
substance=Equivalentweightofsubstanceingrams
MilligramEquivalentWeight:Itisobtainedby
dividingthegramequivalentweightby1000.

18. NormalityofSolution:Normalityisasystemofexpressing
concentrationbasedonnumberofequivalentsofsolute
presentinonelitreofsolutionorthenumberof
milliequivalentsofsolutepresentinonemillilitreofa
solution.
Number of equivalents of the solute
Normality= -------------------------------------------
Volume of titration in litre
Number of milliequivalentsof the solute
= -------------------------------------------------
Volume of the solution in millilitre
Number of gram equivalents = Normality x Litres

19. https://www.youtube.com/watch?v=KLjWa9cE2uk
(molaritymade easy)
https://www.youtube.com/watch?v=hQrih9m_nmQ
https://www.youtube.com/watch?v=QCZMyx_557I
https://www.youtube.com/watch?v=fDh30u -c0Sc
https://www.youtube.com/watch?v=0MwIMhcAWLQ
(normality and equivalent weight)

20. Primary and Secondary Standard Solutions
Thestandardsolutionispreparedbydissolvinganaccurately
weighedquantityofahighlypurematerialcalledaprimary
standardandthendilutingtoanaccuratelyknownvolumeina
volumetricflask
Ifmaterialisnotsufficientlypurethensolutionispreparedto
giveapproximately thedesiredconcentrationandthis
standardizedbytitratingaweighedquantityofaprimary
standard.
https://www.youtube.com/watch?v=xKH2AvS_sOk

21. Theprimarystandardshouldfulfillthebelow
requirements
◦Itshouldbe100%pure
◦Itshouldbestabletodryingtemperaturesandit
shouldbestableindefinitelyatroomtemperature.
Theprimarystandardisalwaysdriedbefore
weighing.
◦Itshouldbeeasilyandreadilyavailable
◦Althoughnotnecessaryitshouldhaveahigh
formulaweight.
Thisissothatarelativelylargeamountofitwill
havetobeweighedtogetenoughtotitrate.
Therelativeerrorinweighingagreateramount
ofmaterialwillbesmallerthanthatforsmall
amount

22. Preparation of Standard Solution
◦Incaseofvolumetricanalysis,thefinalresult
dependsupontheaccuracywithwhichthe
standardsolutionisprepared.
◦Theconcentrationofstandardsolutionis
establishedbydirectandindirectmethod.
DirectMethodofPreparationofStandard
Solution(PrimaryStandard)
◦Inordertoprepareastandardsolution,the
substanceisweighedaccuratelyequaltoan
equivalent,oradefinitefractionormultipleof
anequivalent,dissolvedinwateranddilutedto
aknownvolume.

23. Indirect Method ofPreparation of
StandardSolution(SecondaryStandard)
◦Theprocessofdeterminingtheconcentrationofa
solutionbytitratingitagainstasolutionofapure
substanceofknownconcentrationiscalledas
standardization.
◦Thustheexactconcentrationofthesecondary
standardsolutionisdeterminedbytitratingitagainst
aprimarystandardsolution.
◦Thesecondarystandardsolutionmaybefurtherused
forstandardizationofothersolutions.

24. Equivalent weight in different types of
reactions
◦Therearevarioustypesofchemicalreactions.The
equivalentweightvarieswiththetypeofreaction.
◦Samecompoundsmayhavedifferentequivalentweights
indifferentchemicalreactions.
◦Hencenormalityofaparticlesolutionmayalsobe
differentindifferentchemicalreactions.
◦Equivalentweightindifferenttypesofchemicalreactions
isdiscussedasshownbelow
NeutralizationReactions
ComplexFormationandPrecipitationReactions
Oxidation–Reductionreactions

25. Neutralization reactions
◦Inreactionsbetweenacidsandbases,oneequivalentis
theweightofthereagentwhichcontainsorreactswith
onegramatomofreplaceablehydrogen(1.008g)orwith
onegrammoleculeofhydroxyl(17.008g).
Molecular weight of acid
Equivalent weight of acid = ----------------------------
Basicityof that acid
◦Thebasicityisdefinedasthenumberofreplaceable
hydrogenatomspresentinonemoleculeofthatacid.
◦Thetermacidityisdefinedasthenumberof
replaceablehydroxylionspresentinonemoleculeof
thatbase
Molecular weight of base
Equivalent weight of acid = ----------------------------
Acidity of that base

26. Complex Formation and Precipitation
Reactions
◦Theequivalentweightofcomplex
formationandprecipitationreactionsis
theweightofthesubstancethatcontains
orreactswith1gatomofamonovalent
cationM
+
,½gatomofbivalentcation
M
2+
,1/3gatomofatrivalentcationM
3+
andsoon.
◦Theequivalentweightofcationisequalto
itsatomicweightdividedbyvalency.

27. •The equivalent weight of a substance in complex
formation reaction can be determined by writing
down the ionic equation of the reaction
2KCN + AgNO
3K [Ag(CN)
2] + KNO
3
i.e.2CN-+ Ag+ [Ag(CN)2]-

28. Calibration
Calibration of measuring instruments
https://lab-
training.com/2015/01/06/volumetric-
apparatus-use-calibration/
https://pharmapathway.com/calibration-
procedure-volumetric-glassware/

30. Instrumental analysis
Instrumentalanalysisisafieldofanalyticalchemistrythat
investigatesanalytesusingscientificinstruments.
Instrumentalchemistryinvolvestheuseofcomplex
machineswithinthefieldofanalyticalchemistry.
Thisfieldusesinstrumentstoanalyzeparticlesand
molecules.Partofanalyticalchemistryisexploringhow
theseinstrumentsworkwithintheframeworkofresearch.
Two common methods ofinstrumentation are
spectroscopyandmassspectrometry.Spectroscopyuses
electromagneticradiation,whilemassspectrometryuses
magneticandelectricfields.
Instrumentalchemistryisutilizedwithinthefood,
pharmaceutical,medicalandenvironmentalindustries.

31. Theinstrumentalmethodsofchemical
analysisaredividedintocategories
accordingtothepropertyoftheanalyte
thatistobemeasured.
Manyofthemethodscanbeusedforboth
qualitativeandquantitativeanalysis.
Themajorcategoriesofinstrumental
methodsarethespectral,electroanalytical
andseparatory.

32. Thepossibilitytorealiseanalysesonsmalland
verysmallsamplesisoneofadvantagesof
instrumentalmethods incomparison with
chemicalmethods.
Bothchemicalandinstrumentalanalysis
methodshaveaseriesoflimitation,everyof
themhavingadvantagesanddisadvantages

33. Advantages of Instrumental methods of analysis
UVvisiblespectrometryasmallamountofthesampleis
requiredforanalysis
Determinationbyinstrumentalmethodisconsiderablyfast
Complexmixturecanbeanalyzedeitherwithorwithouttheir
separation
Reliabilityandaccuracyofresultsareobtainedby
instrumentalmethod
Whennon-instrumentalmethodisnotpossible,instrumental
methodistheonlyanswertotheproblem

34. Limitations of Instrumental methods of analysis
Ingeneralinstrumentalmethodsarecostly
Requiremaintenance
Alsorequiretrainedpersonnelforhandling
Thesensitivityandaccuracydependuponthetypeofthe
instrument
Specializedtrainingforhandlinginstrumentisrequired
Thereisfrequentneedofcheckingresultswithother
methods
Insomecasesinstrumentalmethodmaynotbespecific

35. List of Instrumental methods of analysis
UV visible spectrometry
IR spectrometry
Atomic Absorption
spectrophotometry(AAS)
Nuclear magnetic resonance
spectrophotometry
Emission spectroscopy
Fluorometry
Turbidimetry
Conductometry
Polarimetry
Massspectometry
Polarography
Raman spectroscopy
Flame photometry
Radiochemical methods
Potentiometry
Electrogravimetry
Nephelometry
Refractometry
X –ray diffraction
method

36. Instrumental methods
Spectral Electro-analytical Separatory
•Absoptiometry
•NuclearMagneticResonance
•Thermalanalysis
•InfraRed
•UVspectrophotometry
•X-rayabsorption
•Turbidimetry
•Nephelometry
•Refractometry
•Conductometry
•Voltametry
•Polarography
•Electrogravimetry
•Coulometry
•Amperometry
•Potentiometry
•Chromatography
•Massspectrometry

37. Non instrumental analysis
Thechemicalmethods(gravimetricandtitrimetric)from
ensemble ofquantitativeanalysismethods are
correspondingtomacroscaledeterminationswhile
instrumental methods areused forquantitative
determinationsstartingwithsemi–microscale.

38. Chemical methods
(Non instrumental analysis)
The chemical methods have advantages:
Thenecessaryequipmentisveryexpensive;
The methods arebased on absolute
measurements;
Proceduresaresimpleandprecise

39. The chemical methods have disadvantages:
Theprecisiondecreasewithdecreaseofsample
amount;
Therealisationofananalysisisrealisedinaenough
longtimeperiod;
Theyaren’tflexible;
Theyarepollutantforenvironment;
Sometimestheyaren’tspecific