Equilibrium#Practice#Test#

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1 APChemistry12 Name: Date: EquilibriumPracticeTest Block: MultipleChoice: 1.Asystemwillproceedtouilibriuminanattempttoachievea balancebetween A. maximumenthalpyandmaximumentropy. B. minimumenthalpyandminimumentropy. C. maximumenthalpyandminimumentropy. D. minimumenthalpyandmaximumentropy. 2.Considerthereaction: BaCO 3s)+heat BaO s)+co 2 Whichofthefollowingobservationswillindicatethatthereactionhas mostlikelyachieveduilibrium? A. Themassofthesystembecomesconstant. B. TheconcentrationofBaO s)becomesconstant. C. AlltheBaCO 3s)isconsumed. D. Thegaspressureofthesystembecomesconstant. 3.Considerthefollowingreactionatuilibrium: CO 2+NO NO 2+CO ΔH=+82kJ Whichprocedurewillcausethisuilibriumtoshifttotheleft? A. Adecreaseinthetemperature. B. Anincreaseinthetemperature. C. Adecreaseinthevolumeofthesystem. D. Anincreaseinthevolumeofthesystem. 4.QuicklimeCaO),isproducedfromlimestoneCaCO 3),accordingto theuilibriumreaction: heat+caco 3s) CaO s)+co 2 Whichofthefollowingproceduresresultsinproducingthemaximum quantityofquicklime? A. LowerthetemperatureandallowCO 2toescape. B. RaisethetemperatureandallowCO 2toescape. C. LowerthetemperatureandfinelygrindtheCaCO 3. D. RaisethetemperatureandfinelygrindtheCaCO 3. 5.WhichprocedurecausesanincreaseinthevalueofK forthe followingreaction? C s)+2h 2 CH 4ΔH=X74.8kJ A. Decreasethevolume. B. Increasethetemperature. C. Decreasethetemperature. D. FinelypowdertheC s). 6.Explainyouranswertothuestionabove: 7.Considerthefollowinguilibrium: C s)+h 2O CO 2+H 2 Thisuilibriumwillnotshiftwhen A. acatalystisadded. B. thevolumeisdecreased. C. the[h 2O isincreased. D. thetemperatureisincreased. 8.Considertheuilibriumbelow: N 2+2O 2 2NO 2 Whenthevolumeofthesystemisincreased,the A. uilibriumshiftsleftandthe[no 2increases. B. uilibriumshiftsleftandthe[no 2decreases. C. uilibriumshiftsrightandthe[no 2increases. D. uilibriumshiftsrightandthe[no 2decreases. 9.Explainyouranswertothuestionabove:

2 10.Considerthefollowinguilibrium: C s)+2h 2 CH 4 Theuilibriumconstantexpressionis A. K = [H2 B. K = 2 [H2 C. K = [C[H2 D. K = 2 [C[H2 11.Considerthefollowinguilibrium: PCl 5 PCl 3+Cl 2 Temperature K 227 o C o C 33.3 TheincreaseinK showsthatthe A. uilibriumshiftsleftandthereactionisexothermic. B. uilibriumshiftsleftandthereactionisendothermic. C. uilibriumshiftsrightandthereactionisexothermic. D. uilibriumshiftsrightandthereactionisendothermic. 12.Considerthefollowingsystem: P 4s)+6H 2 4PH 3 Whichofthefollowingchangeswouldcausetheabovesystemtoshift right? A. RemovemoreP 4. B. Addacatalyst. C. Decreasepressure. D. Increasesurfacearea. 13.Giventhefollowingsystem: 2CrO 2X 4 aq)+2h + aq) Cr 2O 2X 7 aq)+h 2O l) Whichofthefollowingchemicals,whenaddedtotheabovesystemat uilibrium,wouldresultinadecreasein[cro 4 2X? A. NaOH B. HNO 3 C. Na 2CrO 4 D. Na 2Cr 2O 7 14.Giventhefollowinguilibriumsystem: Br 2 Br 2l) Theuilibriumconstantexpressionfortheabovesystemis: [Br2 l) A. K = [Br2 B. K = [Br2 1 C. K = [Br2 D. K = [Br2 [Br2 l) 15.Forthereaction: A +B AB +heat, thefollowingrepresentstheratioofmoleculesatuilibrium: A = B = AB = WhatcanbeconcludedaboutthevalueofK p? A. K p>>1 B. K p 1 C. K p<<1 D. NothingcanbeconcludedaboutthemagnitudeofK p.

3 16.Considerthefollowinguilibriumsystem: H 2+I 2 2HI ThepercentofI 2,byvolume)isdeterminedintheaboveuilibriumat fourdifferenttemperatures.theresultsaredisplayedinthefollowingpie graphs: PercentofI 2shadedarea)atdifferenttemperatures: TemperatureI TemperatureII TemperatureIII TemperatureIV Fromthisdata,theK valuefortheaboveuilibriumislargestat temperature A. I. B. II. C. III. D. IV. 17.Explainyouranswertothuestionabove: 18.Whichofthefollowinguilibria,allatthesametemperature, favourstheproductstothegreatestextent? A. H 2+I 2 2HI K =5.5x10 1 B. N 2+O 2 2NO K =8.7x10 X2 C. 2HCl H 2+Cl 2 K =1.5x10 X3 D. CO 2+H 2 CO +H 2O K =1.6x AsampleofA wasplacedinareactionvesselandallowedto reachuilibriumaccordingtothefollowingreaction: 3A 4B Theconcentrationofthesubstanceswasplottedagainsttime,andthe followinggraphwasproduced. concentration M) time s) Approximatelywhatisthevalueoftheuilibriumconstant,K c? A B C. 4.0 D CalculateK pforthesystemintheabovuestion. [B [A

4 Problems:* 1. Giventhefollowingreactionatuilibrium: CaCO 3s) CaO s)+co 2ΔH=+110kJ Fora)tod)belowwilltheuilibriumshiftleftorrightornotchangeif a) containervolumeisincreased? b) somecaco 3s)isremoved? c) temperatureisincreased? d) CO 2isadded? e) willk increase,decreaseornotchangeifco 2isadded? f) willk increase,decreaseornotchangeiftemperatureisdecreased? 2. Considerthefollowinguilibriumsystem: Fe 3+ aq)+scn Q aq) FeSCN 2+ aq) light&yellow&&&&&&&&&&colourless&&&&&&&&&&&blood1red& Coolingtheuilibriumchangesthecolourfromyellowtored.Whateffectwillthedecreaseintemperaturehaveon K?Explain,usingLeChatelier sprinciple. 3. Thefollowinggraphrepresentsconcentrationchangesversustimefortheuilibriumreaction: 2NO 2 N 2O 4+Energy 120 [ mol/l) N 2 O 4 NO Time min) a) Atwhattimeisuilibriuminitiallyreached? b) Explainthechangesthatoccurbetween10and20minutes.Indicatethestressappliedandhowthesystem responds. c) Ifthetemperatureofthissystemwasincreasedat20minutes,sketch*directly*on*the*graphhowthe concentrationsofbothsubstanceswouldchange.

5 4. At250 C,K forthefollowingreactionis5.83x SO 2+O 2 2SO 3 IftheuilibriumconcentrationofSO 2is0.012MandthatofO 2is0.049M,whatistheuilibriumconcentrationofSO 3at 250 C? 5. Considerthefollowinguilibriumsystem: H 2+I 2 2HI K =7.1x10 2 & 0.10molofeachofthethreegasesintheabovesystemareplacedina1.0Lcontainerandallowedtocometo uilibrium, a) Willthereactionproceedforwardsorbackwards?Showevidencewithacalculation. b) Whatwillbetheuilibriumconcentrationofall3gases?

6 6. Ina1.00Lcontainer,atuilibrium,thereactionbelow: N 2O 2+H 2 N 2O +H 2O wasanalyzedandfoundtocontain0.200molofn 2O 2,0.300molofH 2,0.500molofN 2O,and0.500molofH 2O.If0.100 molofn 2O 2isadded,whatwillthenewuilibriumconcentrationsbeofbothproducts? 7. Considerthefollowingreaction: SO 3 +SCl 2 SOCl 2 +SO 2 +heat AtaparticulartemperatureK p=15.0.areactionmixturecontainsthefollowingina2.0lcontainer: P SO3=0.25atm PS Cl2=0.50atm P SOCl2=1.00atm P SO2=1.00atm a) Writetheuilibriumconstantexpression,K p,forthereaction. b) Determinewhetherthereactionmixtureisatuilibrium,orwhichdirectionitwillshift.Justifyyouranswer. c) CalculatethevalueforK c.