AQA A LEVEL CHEM PRACTICALS - PAPER 3
QUIZZES WITH ANSWERS GRADED A+
measuring,e.m.f.,of,electrochemical,cells,,,ANS,-
The,standard,cell,potential,is,the,e.m.f.,between,two,half,cells,making,up,the,cell,,measured,under,standa
rd,conditions.
clean,piece,of,each,metal,,e.g.,copper,and,zinc.,degrease,using,propanone,
place,copper,in,a,beaker,with,around,50cm₃,1moldm⁻³,copper,sulfate,solution,,place,zinc,in,a,seperate,be
aker,of,same,concentration,and,volume,zinc,sulfate,solution
join,the,two,beakers,with,filter,paper,coated,in,NaCl/potassium,nitrate,-,acts,as,a,salt,bridge
connect,one,end,to,positive,terminal,of,voltmeter,and,the,other,electrode,to,the,negative,terminal,,ensuri
ng,the,reading,is,positive,-,if,it,is,negative,,reverse,the,connections,to,the,electrodes
record,the,reading,of,the,voltmeter,,writing,which,electrode,is,connected,to,the,positive,and,negative,ter
minals
standard,solution,,,ANS,--
,place,a,known,mass,of,a,sample,in,a,beaker,,add,100cm³m,of,distilled,water,to,beaker,to,dissolve,sample,,
record,mass,to,2,d.p.
-,use,a,glass,rod,to,stir
-,pour,this,solution,into,a,graduated,flask,via,a,funnel
-,rinse,beaker,and,funnel,using,distilled,water,and,add,washings,to,volumetric,flask
-,make,up,to,the,mark,with,distilled,water,so,that,the,meniscus,sits,on,the,line
-,invert,flask,several,times,to,ensure,uniform,solution
Titration,-,known,concentration,in,burette,,unknown,concentration,in,conical,flask,,,ANS,--
,rinse,burette,with,deionised,water,and,then,with,the,solution,you're,using
-,fill,the,burette,past,the,mark,(using,funnel),and,empty,the,burette,until,meniscus,is,on,the,line
-,removal,funnel,so,no,more,solution,can,enter
-
,rinse,pipette,with,deionised,water,and,then,with,the,solution,you're,using.,when,filling,pipette,go,past,th
e,line,then,empty,until,meniscus,is,on,the,line
-rinse,conical,flask,with,deionised,water
, -,pipette,25cm³,of,required,solution,into,conical,flask
-,add,required,indicator
-,swirl,to,mix
-,titrate,the,solution,from,the,burette,,about,1cm³,at,a,time,,until,indicator,changes,colour
*any,drops,or,splashes,up,the,side,of,the,flask,should,be,washed,with,deionised,water
*repeat,titration,adding,solution,dropwise,when,reaching,end,point,-
,record,all,to,2.d.p,but,only,ending,in,0,or,.5,repeat,until,results,are,concordant,(within,.1)
What,may,go,wrong,with,titration?,,,ANS,-may,lose,some,solution,before,it,starts
don't,remove,funnel,so,some,drops,fall,during,titration
may,rinse,conical,flask,with,solution,so,you,have,added,more,solution,to,the,flask
may,not,include,all,of,the,washings
Which,indicator,should,be,used?,,,ANS,-strong,acid,-
,strong,base,=,either,methyl,orange,or,phenolphthalein,(,pink,to,colourless)
weak,acid,-,strong,base,=,phenylphthalein,,strong,acid,-
,weak,base,=,methyl,orange,(,yellow,to,red/orange)
Indicator,must,change,sharply,at,the,equivilance,point,,so,the,pH,range,of,the,indicator,should,fall,within,t
he,'vertical,section',(region,of,rapid,pH,change)
What,happens,in,an,acid-base,titration,,,ANS,-
solution,of,alkali,of,known,concentration,added,from,a,burette,to,a,measured,amount,of,an,acid.,indicato
r,used,to,find,end,point,-,from,volume,of,base,required,,concentration,of,acid,can,be,calculated
How,can,number,of,molecules,of,water,of,crystallisation,be,determined,in,a,practical?,,,ANS,-
titrate,the,aq,solution,,with,known,volume,in,a,conical,flask,and,acid,in,burette,,repeat,titration,until,conc
ordant,results,found.
Use,added,volume,to,work,out,moles,using,molar,ratio.
calculate,mr,using,known,mass,and,number,of,moles,found,-,then,calculate,'x',using,found,mr,-
,mr,of,each,molecule,in,substance,,divided,by,18,to,find,number,of,H2O,molecules
QUIZZES WITH ANSWERS GRADED A+
measuring,e.m.f.,of,electrochemical,cells,,,ANS,-
The,standard,cell,potential,is,the,e.m.f.,between,two,half,cells,making,up,the,cell,,measured,under,standa
rd,conditions.
clean,piece,of,each,metal,,e.g.,copper,and,zinc.,degrease,using,propanone,
place,copper,in,a,beaker,with,around,50cm₃,1moldm⁻³,copper,sulfate,solution,,place,zinc,in,a,seperate,be
aker,of,same,concentration,and,volume,zinc,sulfate,solution
join,the,two,beakers,with,filter,paper,coated,in,NaCl/potassium,nitrate,-,acts,as,a,salt,bridge
connect,one,end,to,positive,terminal,of,voltmeter,and,the,other,electrode,to,the,negative,terminal,,ensuri
ng,the,reading,is,positive,-,if,it,is,negative,,reverse,the,connections,to,the,electrodes
record,the,reading,of,the,voltmeter,,writing,which,electrode,is,connected,to,the,positive,and,negative,ter
minals
standard,solution,,,ANS,--
,place,a,known,mass,of,a,sample,in,a,beaker,,add,100cm³m,of,distilled,water,to,beaker,to,dissolve,sample,,
record,mass,to,2,d.p.
-,use,a,glass,rod,to,stir
-,pour,this,solution,into,a,graduated,flask,via,a,funnel
-,rinse,beaker,and,funnel,using,distilled,water,and,add,washings,to,volumetric,flask
-,make,up,to,the,mark,with,distilled,water,so,that,the,meniscus,sits,on,the,line
-,invert,flask,several,times,to,ensure,uniform,solution
Titration,-,known,concentration,in,burette,,unknown,concentration,in,conical,flask,,,ANS,--
,rinse,burette,with,deionised,water,and,then,with,the,solution,you're,using
-,fill,the,burette,past,the,mark,(using,funnel),and,empty,the,burette,until,meniscus,is,on,the,line
-,removal,funnel,so,no,more,solution,can,enter
-
,rinse,pipette,with,deionised,water,and,then,with,the,solution,you're,using.,when,filling,pipette,go,past,th
e,line,then,empty,until,meniscus,is,on,the,line
-rinse,conical,flask,with,deionised,water
, -,pipette,25cm³,of,required,solution,into,conical,flask
-,add,required,indicator
-,swirl,to,mix
-,titrate,the,solution,from,the,burette,,about,1cm³,at,a,time,,until,indicator,changes,colour
*any,drops,or,splashes,up,the,side,of,the,flask,should,be,washed,with,deionised,water
*repeat,titration,adding,solution,dropwise,when,reaching,end,point,-
,record,all,to,2.d.p,but,only,ending,in,0,or,.5,repeat,until,results,are,concordant,(within,.1)
What,may,go,wrong,with,titration?,,,ANS,-may,lose,some,solution,before,it,starts
don't,remove,funnel,so,some,drops,fall,during,titration
may,rinse,conical,flask,with,solution,so,you,have,added,more,solution,to,the,flask
may,not,include,all,of,the,washings
Which,indicator,should,be,used?,,,ANS,-strong,acid,-
,strong,base,=,either,methyl,orange,or,phenolphthalein,(,pink,to,colourless)
weak,acid,-,strong,base,=,phenylphthalein,,strong,acid,-
,weak,base,=,methyl,orange,(,yellow,to,red/orange)
Indicator,must,change,sharply,at,the,equivilance,point,,so,the,pH,range,of,the,indicator,should,fall,within,t
he,'vertical,section',(region,of,rapid,pH,change)
What,happens,in,an,acid-base,titration,,,ANS,-
solution,of,alkali,of,known,concentration,added,from,a,burette,to,a,measured,amount,of,an,acid.,indicato
r,used,to,find,end,point,-,from,volume,of,base,required,,concentration,of,acid,can,be,calculated
How,can,number,of,molecules,of,water,of,crystallisation,be,determined,in,a,practical?,,,ANS,-
titrate,the,aq,solution,,with,known,volume,in,a,conical,flask,and,acid,in,burette,,repeat,titration,until,conc
ordant,results,found.
Use,added,volume,to,work,out,moles,using,molar,ratio.
calculate,mr,using,known,mass,and,number,of,moles,found,-,then,calculate,'x',using,found,mr,-
,mr,of,each,molecule,in,substance,,divided,by,18,to,find,number,of,H2O,molecules
