chemistry 11 name: mole ii date: block: unit conversions · 2019. 1. 9. · chemistry 11 mole ii...
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Chemistry11MoleII
Name:Date:Block:
1. UnitConversions
UnitConversions• Youmustfollowthesamemethodshownbelow.
• Wecanconvertfromoneunittoanotherbyusingrelationshipsthatareequivalenttoeachotherthen
arrangedasaratio.Theratioiscalledtheconversionfactor.
• Forexample,withtimeweknowthefollowingrelationships:
Relationship ConversionFactor
1min=60s
1min60s
and 601mins
1hour=60min
160minhour and 60min
1hour
24hours=1day
124dayhours
and 241hoursday
Notethatthevaluesintheratiosareequaltoeachother(i.e.1min=60s).Therefore,theratioreally
hasavalueequalto1.Multiplyinganyfactorbytheconversionfactorisequivalenttomultiplyingby1andwillnotchangethevalueoftheexpression.
Thegeneralformulaforsolvingproblemsusingtheconversionfactormethod:
UnknownAmount=(initialamountgivenintheproblem)x(conversionfactor) Examples:
1. Howmanysecondsaretherein49.56minutes?
49.56 minutes × 60 seconds1 minute = 2973.6 seconds = 2974 seconds (4 sig figs)
2. Howmanyhoursaretherein448.2minutes?
3. Howmanyminutesaretherein44days?(2steps)
4. Howmanysecondsaretherein3days?(3steps)
5. Howoldareyouinseconds? Note:
• Alltheunitscanceleachotherexceptthedesiredunit(s).• Theexpression“3days”ismultipliedbythreeconversionfactorsthatareallequivalentto
“1”.Thefinalanswerchangedbecausethe“expression”hasadifferentunit,buttheactualvalueisstillthesame.
6. Ifthedensityofseawateris1.2g/mL,calculatethevolumeof45gofseawater.
45g × 1mL1.2g = 37.5 mL = 38 mL (2 sig figs)
7. Ifacarismovingat50.0km/h,calculatehowfar(inmetres)thecarmovesin5.00seconds.
ALWAYSINCLUDETHEUNITSFORALLTHECALCULATIONSWEDOINCHEMISTRY.DONOTBETEMPTEDTOEXCLUDETHEM!
MoreExamples:
8. Howmanyminutesaretherein1.67week?
9. Howmanycentimetersarein21.598km?
10. Ifyouhave45dozeneggs,howmanyeggsdoyouhave?
11. Ifacarcanmove50.0km/h,howfarcanthecargoin3.2675hours?
12. Onemoleculeofphosphorushas4atoms.Howmanymoleculesaretherein448atomsof
phosphorus?
13. Ifonemoleofcarbonhasamassof12.0g,whatisthemassof4.7molesofcarbon?
14. Thedensityofaluminumis2.7g/mL.Whatisthevolumeof7.4gofaluminum?
15. Ifacaraverages60.0km/h,howlongwillittaketocover57km? “Onlythosewhohavethepatiencetodosimplethingsperfectlywillacquiretheskilltodo
difficultthingseasily.” ~JohannvonSchiller(Germanphilosopher)B.MultipleUnitConversions
16. Howmanyminutesaretherein3days?
17. Theenergyneededtomelt1kgoficerequires334kJ.Thelargestknowniceberghasavolumeofabout3.1x1013m3.Howmuchheatwasrequiredtomelttheicebergif1.0m3oficehasamassof917kg?
18. Howfardoesacargoin10.00secondsifitismovingat50.00km/h?
19. If1yard=3feet,1foot=12inches,and1inch=2.54cm,howmanymetersarein50.00yards?
20. Asprintercanrun100.metresin10.0seconds.Howfastisthesprintermovinginkm/h?
21. Achickenfarmerwishedtopurchaseagiftforhiswife.Thegiftwasworth2horses.Atthelocalmarket,3horseswereworth5cows,1cowwasworth4hogs,3hogswereworth4goats,and1goatcost9chickens.Howmuchwasthegiftgoingtocostthefarmerwhohadtopayinchickens?
22. Trythisthischallengingconversion!Suppose1dip=6dops,1dop=8daps,1tick=13tocks,and1tock=10tacks.Convert21.1dips/tack2intodops/tock2.
1)2974sec2)7.470hr3)63,000min4)3x105sec5)9.2x108sec6)38mL7)69.4m8)1.68x104min9)2.1598x106cm10)540eggs11)163km12)112molecules13)56g14)2.7mL15)0.95hr16)4x103min17)9.5x1018J18)0.1389km19)45.72m20)36.0km/h21)160chickens22)1.27x104dops/tocks2