ANALYTICAL CHEM LAB FINAL C311 QUESTIONS AND CORRECT ANSWERS

ANALYTICAL CHEM LAB FINAL C311
QUESTIONS AND CORRECT
ANSWERS
ConfidenceA2IntervalA2-A2CI=A2meanA2±A2tA2(SD/√n)

StandardA2DeviationA2-A2standardA2deviationA2=A2√[∑(x-mean)²/n-1]

absoluteA2uncertaintyA2-A2theA2maximumA2absoluteA2errorA2allowedA2inA2aA2solution

RelativeA2toleranceA2-A2relativeA2toA2theA2solutionA2value

CoefficientA2ofA2varianceA2-A2SD/A2meanA2xA2100%

relativeA2standardA2deviationA2-A2SD/A2IA2meanA2IA2xA2100%

meanA2-A2averageA2ofA2allA2values

rangeA2-
A2theA2differenceA2betweenA2theA2highestA2andA2lowestA2scoresA2inA2aA2distribution


accuracyA2-
A2AA2descriptionA2ofA2howA2closeA2aA2measurementA2isA2toA2theA2trueA2valueA2ofA2theA2qua
ntityA2measured.

precisionA2-
A2aA2measureA2ofA2howA2closeA2aA2seriesA2ofA2measurementsA2areA2toA2oneA2another


LabA23-A2KMnO4
WhatA2isA2theA2balancedA2reactionA2betweenA2KMnO4A2andA2oxalate?A2-
A22MnO4A2+A25(C2O4)^2-A2+A216H+A2->A210CO2A2+A22MnA2+A28H2O


LabA23-A2KMnO4
WhatA2isA2theA2differenceA2betweenA2acidA2baseA2titrationA2andA2aA2redoxA2titration?A2-
A2acidA2baseA2titrationA2includesA2transferA2ofA2protonsA2andA2aA2redoxA2reactionA2include
sA2transferA2ofA2electrons

LabA23-A2KMnO4
HowA2isA2theA2determinationA2ofA2theA2endA2pointA2differentA2thanA2usingA2phenolphthalei
n?A2-
A2InsteadA2ofA2usingA2phenolphthalein, A2permanganateA2ionA2isA2reducedA2toA2aA2nearlyA2
colorlessA2Mn2+A2whenA2mixedA2withA2sulfuricA2acid

, LabA23-KMnO4
WhyA2isA2itA2necessaryA2toA2performA2aA2blankA2trial?A2-
A2blankA2trialsA2areA2importantA2becauseA2weA2canA2subtractA2thatA2volumeA2fromA2theA2o
neA2weA2recordedA2toA2minimizeA2error

LabA24-A2UV-vis
StateA2theA2rangeA2ofA2lightA2fromA2theA2electromagneticA2spectrumA2thatA2isA2inA2theA2UV
A2regionA2-A2100nm-400A2nm


LabA24-A2UV-vis
WhatA2areA2theA2expectedA2amountsA2ofA2caffeineA2andA2benzoicA2acidA2inA2aA212A2ozA2ca
nA2ofA2mountainA2dewA2andA2sprite?A2-A2MountainA2Dew-A21.67A2mg/ozA2ofA2caffeine
Sprite-A21.35A2mg/ozA2ofA2caffeine
5A2mg/ozA2ofA2benzoicA2acid

LabA24-A2UV-vis
WhatA2isA2theA2conversionA2factorA2betweenA2fluidA2ouncesA2andA2milliliters?A2-
A21A2flA2oz=A229.6A2mL


LabA24-A2UV-vis
IfA2youA2areA2givenA2aA2stockA2solutionA2ofA2caffeineA2andA2benzoicA2acidA2ofA220A2mg/
LA2andA210A2mg/
LA2respectively,A2showA2calculationsA2toA2makeA2theA2followingA2dilutionsA2inA2aA2totalA2vol
umeA2ofA25A2mLA2ofA2water.A2Caffeine:A216A2mg/L,A213A2mg/L,A210A2mg/L,A24A2mg/
L.A2BenzoicA2acid:A28A2mg/L,A26A2mg/L,A24A2mg/L,A22A2mg/LA2-A2(20)(V)=(16)(5)
V=A24A2mLA2stockA2-A21A2mLA2ofA2water
(20)(V)=(13)(5)
V=A23.25A2mLA2stock-A21.75A2mLA2ofA2water
(20)(V)=(10)(5)
V=2.5A2mLA2stock-A22.5A2mLA2ofA2water
CaffeineA2^^^^^
(10)(V)=(8)(5)
V=A24A2mLA2ofA2stock-A21A2mLA2ofA2water
(10)(V)=(6)(5)
V=3A2mLA2ofA2stock-A22A2mLA2ofA2water
(10)(V)=(4)(5)
V=A22A2mLA2ofA2stock-A23A2mLA2ofA2water
benzoicA2acid^^^^^

LabA25-A2LC
ThisA2experimentA2isA2reverseA2phaseA2chromatography,A2whatA2doesA2thisA2tellA2youA2ab
outA2theA2polarityA2ofA2theA2mobileA2andA2stationaryA2phases?A2-
A2nonpolarA2stationaryA2phase
polarA2mobileA2stationaryA2phase

LabA25-A2LC