ANALYTICAL CHEMISTRY (LAB):
TEST 1 QUESTIONS AND CORRECT
ANSWERS
IdentifyA23A2mainA2potentialA2sourcesA2ofA2errorA2inA2theA2chlorideA2experimentA2-A2Ans--
1.ExposingA2theA2AgClA2precipitateA2toA2sunlightA2causingA2photodecompositionA2ofA2Ag.
2.A2WashingA2theA2coagulatedA2AgClA2precipitateA2withA2largeA2amountA2ofA2waterA2causi
ngA2itA2toA2revertA2toA2colloidalA2formA2andA2losingA2itA2whileA2filtering.A2(AsA2manyA2ofA2yo
uA2couldA2seeA2theA2filtrateA2turningA2cloudyA2whileA2filtering).
3.A2NotA2addingA2enoughA2AgNO3A2causingA2incompleteA2precipitationA2ofA2chlorideA2orA2
notA2addingA2enoughA2HNO3A2whichA2providesA2electrolyteA2forA2precipitateA2toA2formA2an
dA2particleA2growth
GF=A2-A2Ans--MMA2analyteA2/A2MMA2precipitate
WhyA2doA2youA2addA2HClA2toA2theA2mixtureA2ofA2BaCl2A2andA2Na2SO4?A2-A2Ans--
ByA2keepingA2theA2solutionA2acidic,A2weA2reduceA2theA2chanceA2ofA2dissolvedA2CO2A2from
A2theA2airA2reactingA2withA2theA2BariumA2toA2formA2bariumA2carbonateA2(s)A2andA2coprecipi
tateA2withA2BaSO4.
HowA2doA2youA2checkA2theA2purityA2ofA2BaSO4A2crystalsA2formed?A2-A2Ans--
SinceA2youA2startedA2withA2BaCl2A2andA2Na2SO4A2theA2onlyA2otherA2possibleA2substance
A2mightA2beA2NaCl,A2YouA2couldA2testA2forA2thatA2byA2washingA2theA2BaSO4A2crystals,A2an
dA2thenA2afterA2decantingA2it,A2testA2itA2withA2AgNO3,A2ifA2anyA2NaClA2wasA2presentA2inA2th
eA2BaSO4A2itA2shouldA2dissolveA2andA2causeA2aA2precipitateA2ofA2AgClA2inA2theA2washA2w
ater.
InA2thisA2experimentA2youA2usedA2anA2excessA2ofA2theA2BaCl2A2solution.A2HowA2wouldA2yo
urA2resultsA2beA2affectedA2ifA2youA2didA2notA2useA2anA2excessA2ofA2theA2BaCl2A2solution?
A2WouldA2thisA2errorA2causeA2yourA2calculationA2ofA2theA2massA2percentA2ofA2sulfateA2inA2t
heA2unknownA2toA2beA2tooA2highA2orA2tooA2low?A2Explain.A2-A2Ans--
ExcessA2ofA2BaCl2A2ascertainA2completeA2conversionA2ofA2sulfateA2intoA2BaSO4.A2IfA2BaC
l2A2isA2notA2inA2excess,A2massA2%A2ofA2BaSO4A2willA2beA2lowerA2thanA2actual.
TheA2unknownA2metalA2sulfatesA2areA2hygroscopicA2andA2willA2absorbA2waterA2fromA2air.A2
TheA2unknownsA2mustA2thusA2beA2keptA2inA2desiccatorsA2toA2removeA2anyA2absorbedA2wa
ter.A2HowA2wouldA2yourA2resultsA2beA2affectedA2ifA2yourA2unknownA2sampleA2wasA2notA2de
siccated?
A2WouldA2thisA2errorA2causeA2yourA2calculationA2ofA2theA2massA2percentA2ofA2sulfateA2inA2t
heA2unknownA2toA2beA2tooA2highA2orA2tooA2low?A2Explain.A2-A2Ans--
ImpurityA2ofA2waterA2inA2theA2unknown,A2willA2reduceA2theA2amountA2ofA2SO4A2inA2theA2me
TEST 1 QUESTIONS AND CORRECT
ANSWERS
IdentifyA23A2mainA2potentialA2sourcesA2ofA2errorA2inA2theA2chlorideA2experimentA2-A2Ans--
1.ExposingA2theA2AgClA2precipitateA2toA2sunlightA2causingA2photodecompositionA2ofA2Ag.
2.A2WashingA2theA2coagulatedA2AgClA2precipitateA2withA2largeA2amountA2ofA2waterA2causi
ngA2itA2toA2revertA2toA2colloidalA2formA2andA2losingA2itA2whileA2filtering.A2(AsA2manyA2ofA2yo
uA2couldA2seeA2theA2filtrateA2turningA2cloudyA2whileA2filtering).
3.A2NotA2addingA2enoughA2AgNO3A2causingA2incompleteA2precipitationA2ofA2chlorideA2orA2
notA2addingA2enoughA2HNO3A2whichA2providesA2electrolyteA2forA2precipitateA2toA2formA2an
dA2particleA2growth
GF=A2-A2Ans--MMA2analyteA2/A2MMA2precipitate
WhyA2doA2youA2addA2HClA2toA2theA2mixtureA2ofA2BaCl2A2andA2Na2SO4?A2-A2Ans--
ByA2keepingA2theA2solutionA2acidic,A2weA2reduceA2theA2chanceA2ofA2dissolvedA2CO2A2from
A2theA2airA2reactingA2withA2theA2BariumA2toA2formA2bariumA2carbonateA2(s)A2andA2coprecipi
tateA2withA2BaSO4.
HowA2doA2youA2checkA2theA2purityA2ofA2BaSO4A2crystalsA2formed?A2-A2Ans--
SinceA2youA2startedA2withA2BaCl2A2andA2Na2SO4A2theA2onlyA2otherA2possibleA2substance
A2mightA2beA2NaCl,A2YouA2couldA2testA2forA2thatA2byA2washingA2theA2BaSO4A2crystals,A2an
dA2thenA2afterA2decantingA2it,A2testA2itA2withA2AgNO3,A2ifA2anyA2NaClA2wasA2presentA2inA2th
eA2BaSO4A2itA2shouldA2dissolveA2andA2causeA2aA2precipitateA2ofA2AgClA2inA2theA2washA2w
ater.
InA2thisA2experimentA2youA2usedA2anA2excessA2ofA2theA2BaCl2A2solution.A2HowA2wouldA2yo
urA2resultsA2beA2affectedA2ifA2youA2didA2notA2useA2anA2excessA2ofA2theA2BaCl2A2solution?
A2WouldA2thisA2errorA2causeA2yourA2calculationA2ofA2theA2massA2percentA2ofA2sulfateA2inA2t
heA2unknownA2toA2beA2tooA2highA2orA2tooA2low?A2Explain.A2-A2Ans--
ExcessA2ofA2BaCl2A2ascertainA2completeA2conversionA2ofA2sulfateA2intoA2BaSO4.A2IfA2BaC
l2A2isA2notA2inA2excess,A2massA2%A2ofA2BaSO4A2willA2beA2lowerA2thanA2actual.
TheA2unknownA2metalA2sulfatesA2areA2hygroscopicA2andA2willA2absorbA2waterA2fromA2air.A2
TheA2unknownsA2mustA2thusA2beA2keptA2inA2desiccatorsA2toA2removeA2anyA2absorbedA2wa
ter.A2HowA2wouldA2yourA2resultsA2beA2affectedA2ifA2yourA2unknownA2sampleA2wasA2notA2de
siccated?
A2WouldA2thisA2errorA2causeA2yourA2calculationA2ofA2theA2massA2percentA2ofA2sulfateA2inA2t
heA2unknownA2toA2beA2tooA2highA2orA2tooA2low?A2Explain.A2-A2Ans--
ImpurityA2ofA2waterA2inA2theA2unknown,A2willA2reduceA2theA2amountA2ofA2SO4A2inA2theA2me
