ANALYTICAL CHEMISTRY LAB EXAM QUESTIONS AND CORRECT ANSWERS

ANALYTICAL CHEMISTRY LAB EXAM
QUESTIONS AND CORRECT ANSWERS

WhatA2isA2meantA2byA2"ClassA2AA2Glassware"A2andA2"ClassA2BA2Glassware"?
A2WhichA2typeA2ofA2glasswareA2isA2referredA2forA2analyticalA2volumeA2measurements?A2-
A2Ans--
ClassA2AA2glasswareA2isA2preferredA2forA2analyticalA2volumeA2measurementA2becauseA2itA
2providesA2theA2highestA2accuracyA2andA2compilesA2withA2ClassA2AA2volumetricA2toleranc
es.A2ClassA2BA2glasswareA2hasA2volumetricA2tolerancesA2greaterA2thanA2ClassA2AA2andA2t
heyA2complyA2withA2ClassA2BA2glassware.

WhatA2doA2theA2symbolsA2"TD"A2andA2"TC"A2meanA2onA2volumetricA2glassware?
A2WhichA2devicesA2areA2associatedA2withA2eachA2usingA2aA2volumetricA2device?A2-A2Ans--
TDA2standsA2forA2"toA2deliver"A2andA2whichA2isA2onA2graduatedA2cylinders,A2burets,A2andA2
pipets.A2TCA2standsA2forA2"toA2contain"A2whichA2isA2onA2volumetricA2flasks.

WhatA2isA2parallaxA2error?
A2WhatA2stepsA2canA2beA2takenA2toA2minimizeA2thisA2typeA2ofA2errorA2whenA2youA2areA2usi
ngA2aA2volumetricA2device?A2-A2Ans--
AA2parallaxA2errorA2isA2whenA2youA2lookA2atA2theA2miniscusA2incorrectly.A2ToA2avoidA2thisA2
measureA2theA2waterA2levelA2atA2theA2bottomA2ofA2theA2meniscusA2whenA2theA2waterA2leve
lA2isA2atA2eyeA2level.

ExplainA2whyA2itA2isA2importantA2toA2calibrateA2volumetricA2devices.A2HowA2doesA2tempera
tureA2affectA2thisA2calibration?A2-A2Ans--
ItA2isA2importantA2toA2calibrateA2volumetricA2devicesA2inA2orderA2toA2obtainA2theA2mostA2ac
curateA2measurementA2possible.A2GlasswareA2canA2expandA2orA2contractA2withA2different
A2temperatures.


AA250.00A2mLA2volumetricA2flaskA2isA2filledA2atA230CA2withA2deionizedA2water.A2TheA2mass
A2ofA2theA2waterA2inA2theA2flaskA2atA2thisA2temperatureA2(asA2readA2directlyA2fromA2theA2bal
ance)A2isA247.7380g.A2
a)WhatA2isA2theA2trueA2internalA2volumeA2ofA2theA2flaskA2atA230C?
A2YouA2mayA2assumeA2aA2densityA2ofA20.0012A2g/
mLA2forA2theA2surroundingA2airA2andA2thatA2theA2balanceA2hasA2beenA2calibratedA2withA2an
A28.0g/mlA2referenceA2weight.
b)WhatA2isA2theA2trueA2volumeA2ofA2theA2volumetrucA2flaskA2atA220C?A2-A2Ans--
a)A250.01A2mL
b)A250.00A2mL

ShowA2howA2youA2wouldA2prepareA2250mLA2ofA2aA20.10MA2NaClA2solutionA2inA2theA2lab.A2-
A2Ans--1.47gA2NaClA2dissolvedA2inA2250A2mLA2water

, YouA2pipettedA225mLA2ofA20.10MA2NaClA2intoA2250A2mLA2ErlenmeyerA2flaskA2toA2whichA25
A2dropsA2ofA2indicatorA2andA20.05gA2ofA2dextrinA2haveA2beenA2added.A2ThenA2youA2carried
A2outA2theA2titrationA2inA2diffuseA2lightA2toA2theA2equivalenceA2point.
a)A2WhatA2isA2theA2titrantA2inA2thisA2titration?
b)A2WriteA2theA2molecular,A2completeA2ionicA2andA2netA2ionicA2equationsA2forA2theA2titratio
nA2reaction
c)A2WhyA2isA2theA2titrationA2carriedA2outA2inA2diffuseA2light?
d)A2WhatA2isA2theA2functionA2ofA2dextrin?
e)A2WhatA2volumeA2ofA20.12MA2AgNO3A2isA2requiredA2toA2reachA2theA2equivalenceA2point
?A2-A2Ans--a)AgNO3
b)NaClA2+A2AgNO3A2-->A2NaNO3A2+A2AgCl
A2Cl-A2+A2AgA2-->A2AgCl
c)A2DiffuseA2lightA2isA2usedA2toA2minimizeA2theA2possibleA2errorA2ofA2photocompositionA2of
A2AgClA2whichA2isA2whenA2thereA2isA2aA2purple-blackA2hueA2onA2topA2ofA2theA2whiteA2AgCl.
d)DextrinA2isA2usedA2toA2preventA2colloidalA2particlesA2fromA2coagulatingA2andA2theA2reduc
tionA2ofA2precipitatesA2surfaceA2area.
e)A20.021LA2AgNO3

AA20.2334gA2quantityA2ofA2primaryA2standardA2NaClA2isA2dissolvedA2inA2250.00mL.A2AA210
.00mLA2aliquotA2ofA2thisA2solutionA2consumesA214.32mLA2ofA2aA2silverA2nitrateA2solutionA2
beforeA2reachingA2theA2endA2pointA2inA2aA2FajansA2titration.A2AA2chlorideA2solution,A2prepa
redA2byA2dissolvingA20.2789gA2ofA2anA2unknownA2sampleA2inA2250.00mLA2takingA2aA210m
LA2aliquotA2ofA2theA2resultingA2solution,A2requiresA211.21mLA2ofA2theA2sameA2silverA2nitrat
eA2solutionA2toA2reachA2theA2endA2point.A2WhatA2percentageA2chlorideA2(w/
w)A2doesA2theA2unknownA2containA2-A2Ans--39.79%

WhatA2isA2meantA2byA2argentometricA2titration?A2-A2Ans--
ArgentometricA2titrationsA2areA2titrationsA2thatA2involveA2silverA2(1)A2ion

ExplainA2theA2principlesA2ofA2absorptionA2indicators.A2UseA2theA2FajansA2methodA2asA2exa
mple.A2-A2Ans--
WhenA2AgA2isA2addedA2toA2ClA2excessA2ClA2isA2absorbedA2ontoA2theA2AgClA2surfaceA2crea
tingA2aA2negativeA2chargeA2priorA2toA2theA2equivalenceA2point.A2AfterA2theA2equivalenceA2p
ointA2excessA2AgA2isA2absorbedA2ontoA2theA2AgClA2surfaceA2creatingA2aA2positiveA2charge
.A2TheA2negativilyA2chargedA2dyeA2partilesA2areA2absorbedA2ontoA2theA2positivelyA2charge
dA2surface,A2signalingA2theA2endA2pointA2ofA2theA2titrationA2byA2theA2colorA2change..

WhyA2weA2needA2toA2standardizeA2NaOHA2andA2HCl?A2-A2Ans--
SoA2thatA2weA2knowA2theA2exactA2concentrationA2resultingA2inA2increasingA2reproducibility
A2ofA2anA2experiment


WhyA2areA2KHPA2andA2Na2CO3A2usedA2asA2primaryA2standards?A2-A2Ans--
PrimaryA2standardsA2shouldA2beA2100%A2pure,A2theyA2mustA2beA2easyA2toA2obtain,A2purity
,A2dryA2andA2preserve,A2theyA2shouldA2notA2changeA2inA2airA2duringA2weighing,A2theyA2sho
uldA2beA2ofA2highA2relativeA2molarA2mass,A2theyA2shouldA2beA2readilyA2solubleA2underA2the