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BasicChemistry—Mid-termExam 1
Name:________________________________
Studentnumber:_______________________
AutumnSemester
BasicChemistryforEngineering/FundamentalInorganicChemistry
Mid-termExam
07December2015
Time:60minutes
Instructions:Answerany4questionsoutof5possiblequestions.Youmayanswermorethan4questionsifyouwish.Yourmarkswillbetakenfromyourtop4questions.Showallrelevantworking.Writeallanswersandfinalworkinginpen.Giveyouranswertoanappropriatenumberofsignificantfigures.9pagesincluding:1toppage,1datapage,1periodictable,5questionpages,1pageforroughworkingHandinallpagesattheendoftheexam.Permissiblematerials:Calculator.EnglishorEnglishbilingualDictionary.
BasicChemistry—Mid-termExam 2
EquationsandData
pV=nRTwherep=pressure,V=volume,n=no.ofmolesofgas,R=8.3144JK–1mol–1orR=0.082057LatmK–1mol–1,T=temperatureinKelvin0˚C=273KAvagadroconstant6.022x1023mol–1pH=–log10[H+]PartialpressureofCO2inairatsealeveland25.0°C:0.000390atmSolubilityofCO2inH2Oat25.0°C:0.14gper100mlH2O.Commonoxidationstates:H:+1,O:–2,Halogens:–1,Group1metals:+1,Group2metals:+2.Otherelementsarevariable.MaximumvapourpressureH2Oat 12.0°C:0.0193atm 22.0°C:0.0690atm 25.0°C:0.0789atmTableofelectronegativities
BasicChemistry—Mid-termExam 4
Question1A)Ageologistproposesusingironoxide(Fe2O3)toloweratmosphericcarbondioxidelevelsbythereaction:
Fe23+O32–+CO2+Li→Fe2+(CO3)2–+Li+O2–
i) This reaction contains mistakes. Write a properly balanced equation below:
[2] ii) Choose one word that best describes this reaction from the following list:
Redox, Displacement, Bronsted-Lowry acid/base, Combination, Dissociation ___________________
[1] iii) A chemist performs a test on the reaction in part i) using a 1.00 L sealed, metal cylinder filled with air at 1.00 atm pressure and 25.0 °C. If she reacts 5.00 g of Fe2O3 with the CO2 of the air inside the cylinder, will all of the CO2 be consumed? ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________
[6] iv) What will the final total gas pressure be inside the cylinder? (Note Fe2O3 and Fe(CO3) are solids, their contribution to pressure is insignificant). ________________________________________________________________________________
[1]
BasicChemistry—Mid-termExam 5
Question2A)Carbondioxide(CO2)reactswithwater(H2O)tomakecarbonicacid(H2CO3).i)Writeabalancedequationforthisreaction:
[1]
ii)Assumingthatcarbonicaciddissociatescompletelyinwater,writeabalancedequationforthedissociationofcarbonicacidinwater.
[1]iii)Whatkindofacidiscarbonicacid?___________________________
[1]iii)Achemistleaves1.00Lofdistilledwateropentotheairat25.0°Covernight.Thenextday,hefindsthepHhasdroppedbelow7.0.WhatisthenewpHofthewater,assumingthedropinpHisduetodissolvedCO2?(useyourequationsfromabove)________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________
[6]iv)Inreallife,thismuchCO2doesnotmakewaterveryacidic.Explainwhythisis.________________________________________________________________________________
[1]
BasicChemistry—Mid-termExam 6
Question3A)Bauxiteisakindofrockthatcontainsalargeproportionofaluminiumoxide(Al2O3).Thealuminiumoxideispurifiedfrombauxiteandthendissociatedintoaluminium(Al)andoxygen(O2)byastrongelectriccurrent.Usethewords‘element’,‘compound’,or‘mixture’todescribei)bauxite,___________________________ii)aluminiumoxide,___________________________
[2]iii)WhatisthemostlikelyoxidationstateofAlinAl2O3?________________________________________________________________________________
[1]vi)Assumingthisisthemostfavouredoxidationstateofaluminium,doyouexpectaluminiummetal(Al0)tobeagoodoxidisingagentoragoodreducingagent?Why?________________________________________________________________________________ ________________________________________________________________________________
[2]
v)IsAl2O3mostlikelytobeanioniccompound,acovalentcompoundorsomewhereinbetween?Why? ________________________________________________________________________________ ________________________________________________________________________________
[2]vi)AstudentbelievesAl2O3isacovalentcompoundanddrawsaLewisdiagramtodemonstrateherreasoning.Giventhatthethreeoxygenatomsareeachbondedtobothaluminiumatoms,drawasuitableLewisdiagramofAl2O3.
[2]
vi)Doesthiscompoundobeytheoctetrule?Why?________________________________________________________________________________
[1]
BasicChemistry—Mid-termExam 7
Question4A)i)Thediagrambelowshowsaneutralatom.Labelthediagram
[2]
iii)Whichelementisthis?___________________________
[1]Thiselementmakescompoundswithsodium(Na)oftheformNaX3(Replace‘X’withtheappropriatechemicalsymbol).Howmuchofthiselement(grams)wouldyouneedtomake15.0gofNaX3?________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________
[4]
AssumethatallatomsinNaX3areionised.GiventhatXhastwodifferentoxidationstatesinthiscompound,writeacceptableoxidationstatesforallionsintheform:Nan,Xn,Xn,Xn(e.g.forH2OyouwouldwriteH+,H+,O2–)(Note:morethanoneanswerispossible,chooseonecombination)________________________________________________________________________________
[3]
BasicChemistry—Mid-termExam 8
Question5A)Humidityisameasureoftheactualvapourpressureofwaterasapercentageofitsmaximumpossiblevapourpressureatagiventemperature.i)Acomfortablehumidityistypically50%.Whatpartialpressureofwatervapourdoesthiscorrespondtoat25.0°C?________________________________________________________________________________
[1]ii)Onacoldday(12.0°C),apersonnotesthehumidityoftheirroomis50%.Theyturnontheirheaterandheattheroomto22.0°C.iii)Assumingnosignificantevaporationofwater,whatwillhappentothehumidityoftheroom?Why?________________________________________________________________________________
[2]iv)Giventhatthecomfortablerangeofhumidityis40—60%,willtheroombetoodry,comfortableortoohumid?________________________________________________________________________________ ________________________________________________________________________________
[3]
B)Achemisttakesa1.00Lcontaineranda2.00Lcontainer,bothhalf-filledwithwater.The1.00Lcontainerissealedwithairintheemptyspaceatatmosphericpressure(1.00atm)andat25.0°C.The2.00Lcontainerissealedwithairat10.0atmpressure.At25.0°C,whatwillthevapourpressureofwaterbe:i) inthe1.00Lcontainer?___________________________ inthe2.00Lcontainer?___________________________
[1]ii)Whatwillthetotalpressurebeinthe1.00Lcontainer?___________________________Whatwillthetotalpressurebeinthe2.00Lcontainer?___________________________
[1]
iii)Howmanymolesofwaterwillbeinthevapourphaseinthe2.00Lcontainer?
________________________________________________________________________________ ________________________________________________________________________________
[2]