University:
High School
Course:
High School Chemistry
Academic year:

2019
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398

Pages:

12
Author:

flapav3

12. As iodine molecules change from the solid to the vapor pliase the entтopy @J1.creases Ь. decreases с. remains the same , 13. When solid ammonium chloгide is dissolved in а beaker ofwateг, the temperature of the шixture ,derreases. The reaction occuпing in the beaker is 1 а. exotheпnic and spontaneous Ь. exothermic and not spontaneous ' @ndotheгmic апd spontaneous • d. endotheгmic апd not spontaneous 14. As the activation energy of а гeaction decгeases because oftl1e additioп ofа catalyst, the heat of reaction - Л Н· Ь. decreases а. шcreases �шаiпs the same 15. Which plлase best describes the reactioп below? C (s) + 1/2 02 -----?> CO( gJ + 26.4 kcal � exotl1er111ic with an increase in entтopy Ь. exotl1er111ic with а decrease in entтopy с. endotl1er111ic with an increase in entropy d. endothe1mic witl1 а decrease in entropy 16. As пitrogen reacts with oxygen in the equation slюwn, tl1e heat offorшatioп for nitтogen dioxide is N2 + 202 + 16.2 kcal -----;;> 2NO2 а. - 8.1 kcal/шole С:)+ 8.1 kcal/шole Ь. - 16.2 kcal/mole d. + 16.2 kcal/шole 17. In а reveгsiЬ!e reaction, t�tween the ac:iva:ion eпergy ofthe fo r· w · a d _ -. . _..· - ·· reactюn and the act1vatюn energy ofthe reverse reactюn 1s equal to the � § а. РЕ ofthe activated complex @eat ofreaction � - .;,. . d. РЕ ofproducts с. РЕ ofreactants 0 Use tl1is гeaction to апswег questions 18 & 19: Н2 (gJ 1/2 02 (g) ----- ➔ Н2O (g) + --- •·· 57.8 kcal 18. Ifthe activatioп energy for tl1e forward reaction is 40.0 kcal/mole, tl1e heat of reaction IS а. - 17.8 kcal/mole с. - 40.0 kcal/шole - 57.8 kcal/mole 97.8 kcal/mole j\l:. t(oP-\ --1> ''!О 19. Ifthe activatioп eпergy for tl1e forward reactioп is 40.0 kcal/шole, the activation eпergy for the гeverse reaction is а. 17.8 kcal/шole Ь. 30.0 kcal/mole с. 60.0·kcal/шole {!)97.8 kcal/mole 1'\� {f!:t.J) 27. Ап iпcrease iп tempeгature iпcreases tl1e гаtе of а chemical reactioп because tl1e а. activatioп eпergy iпcreases @ of moleculaг collisioпs iпcreases Ь. activatioп eпergy decгeases d. # of moleculaг collisio11s decreases Base your aпswers to questioпs 28 - 32 011 the poteпtial eпergy diagram below: А + В + 20 kcal -----> С -------- ---------------:.,-----=--------------------- -i---- ;2_- с -------- --- ----------------------------""--=�-+-- l.cO- d'-0 "' чо 28. Ifthe activatioп епегgу for the forward reactioп is 60 kcal, theп tl1e activatioп епеrа for the reveгse reactioп is а. 60 kcal Ь. 20 kcal с. 30 kcal 040 kcal 29. Tl1e activatioп eпergy for the reverse reactioп is гepreseпted Ьу aiтow а. 1 d. 4 с. 3 (!)i . 30. The heat ofгeactioп is гергеsепtеd Ьу апоw ь. 2 с. 3 (vi . d.4 31. Т11е poteпtial епегgу of the activated complex is represeпted Ьу апоw Ь. 2 d. 4 а. 1 С) · 32. Compared to the poteпtial eпergy ofthe activated complex oftl1e fOiwaгd reactioп, fue poteпtial eпergy ofthe activated complex offue reverse reaction is а. less Ь. greater (3he same . 33. According to Reference ТаЬ!е I, tl1e greatest �mouпt of energy would Ье released . during the combustion of @)с бН12Об • , а. СНзОН СН4 с. СзНs _ ,ц S< --";;> 35. Is the reaction exothermic or endothermic? Give а reason for your answer: �cJc � Still higher entropy � J,,\,creu:s ib_, u.�_+r_op---'t-..1----H_ig.:_h_e_n_t_,o..:_p_y_______L_o_w_e_nt_ro_p_y_____�-Fi 9 u, е 8-9. Entropy: Entropy is а measure of disorder orrandomness. It is usually necessary for particles to collide in а special way in order to form а more higbly organ ,zed or regular arrangement. On the other hand, there are many ways in which they can collide to produce more disorder. Therefore, it is to Ье expected that systems will often go from conditions of greater order (lower entropy) to conditions of greater disorder (higher entropy). On the basis of entropy change alone, we expect reactions to go in the direction of greater entropy. Examples of entropy change are physical changes from the solid, crystalline phase (great order, low entropy ), to the liquid phase (more ran domness, higher entropy), to the gaseous phase (maximum randomness, highest entropy). For chemical changes, compounds represent а state of greater order and lower entropy than the free ele ments ofwhich they are composed. г.-, l'J ...,, .. �;:�� Review Quest1ons . . ,,,,. , Which change in а sample ofwater is accompanied •• �the greatest increase in entropy? - --- ' � • _ l{]JH,O(f) at 1 ОО'С is changed to H2O(g) at 2oq c;. •.•·· · (2) H,O(g) at 1 ОО0С is i:hanged to H,O(g) at 2ро с:: (3) H,O(s) at -1 ОО0С is changed to H,O(s) at О0С (4) H2O(t') at -100°с is changed to H2O(i)-at Ь0с .-. 0 0 (i;-). What o _rs when а sample of CO2(s) changes to CO2(g).� (1 The gas has greater entropy and less order. ( The gas has greater entropy and more order. (3) The gas has less entropy and less order. (4) The gas has less entropy and more order. Ь fi'., Тhе diagram below shows а system of gases with the V valve closed. As the valve is openeq e entropy ofthe gaseous (2) ncreases (3) remains the system (1) decreases � same (4) depends on t е temperature • ® Which series of physical changes represents an entropy increase during each change? (1) gas ➔ liquid ➔ solid (2) liquid ➔ gas ➔ solid .PNolid ➔ gas ➔ solid �olid ➔ liquid ➔ gas • . @ Which tendencies favor а spontaneous reaction? (1) lower energy and decreasing entropy � lower energy and increasing entropy (3) higher energy •. and decreasing entropy (4) higher energy and increasing entropy ENTROPY Entropy is the degree of randomness in а substance. The symbol for change in entropy is лs. Solids аге very ordered and have low entropy. Liquids and aqueous ions have more entropy because they move about more free ly, and gases have an even larger amount of entropy. According to the Second Law of Thermodynamics, nature is always proceeding to а state of higher entropy. _t�--·____ Determine whether the following reactions show an increase ог decrease in entropy. 1. 2KClO3(s) -+ 2KCl(s) + ЗOz, А) "' с ш 7ii .," о � с ш С) "'с C:l " с о. Reaction Coordinate >, ) D) +285.8 kJ Reaction Coordinate � с ф D) Reaction Coordinate ш 7ii с "- Reaction Coordiпate ) =� ,,,,,........,,,,, / ·/) \.V!1icl1 iпt'ormation atюut а cJ1cmical rcactioп is providcd Ьу а potcпtial cncrgy diagram? � t!1c avcragc kinctic cncrgy of thc re�1cta11ts and �roducts /� tl1c cпcrgy rclcascd or absorbed durшg tl1c rcactюn С) tl1c с!шпgс in so!ubility of tl1e·гeacting substanccs D) tl1c oxidation statcs of the reactants and products \V!1cn a-spark is applied to а rnixtшe ofl1ydrogcn and oxygcn, the gases rcact exp!osivcly. Whic!1 potcntial cпcrgy dia!�/am • ьest rcprcscnts tlrc rсасtюп.? _8) '-'---- . ,, ��====:;:/ & Reaction Coordinate 61 � ('i,)j)_I\__ & Reaction Coordinate D) В) Reaction Coordinate Reaction Coordinate Gi\'CП thc rcaction: _9) \\.Ъich diagram best represents the potentiaI елегgу chaлges for this rcaction? • 1 G ,· - "' - "' -� >. �tf] �ф - "' С) Reaction Coordinate - с: сi:ш - "' -� >-, Reaction Coordir1ate -� >. с:� "'ф В) .� >с: � а, а, - с: сi:ш D) Reaction Coordinate с: � ф а, - с: сi:ш Reaction Coordinate L ')._ О - _10) Т/1с potcпtiaJ cncr,gy liiagram l)c!O\V rc.prcscпts а rcactjon. <1) шс: .!31 А о !l. Reaction Coordinate \V!1icЬ ШТО\V rcprescnts tJ1c activatioп cпcrgy of thc fonvard reaction? А) А _11) _12) ® D) D С) С \\l'hich cvent must alн"ar1,· оссuг for а chcшica] rcaction to take place? А) formation of а prccipitatc В) formation ·of а gas Incrs:asing the tcmperaturc increases the rate of а rcaction Ьу ddition of а cataly.st to thc reactioп systcш ....-� vffectivc coJJisions bct\VCCП rcacting particJcs А) ]O\Vt:ring tl1c freqнency of eJfecti\·e coШsions Ьсt\У"ССП reactiпg inokcu]cs В iлcreasing the activation energy / шcrcasiлg the freqt1ency of effcct1v·c coll1s10пs bctv.:ecn геасtшg moJecuies ) lo\vcгing thc activation cnergy _13) Iл шust aqш;ous reactioлs as teшperature incrcascs, the cffccti\'cncss of coIJisions bct\\rceп rcactiлg particlcs В) E?![)iпcreascs _14) decreascs С) rcmains the sзте Ba:;cd оп thc лature of thc rcactants in еасЬ of the equatюns bclo\v. \\.J11ch reaction at 25 °С\\ 111 occur а! tfle fa:.1es1 ratc"' vaOН(aq) + НСJ(ач)- NaCl(aq) + Н2О(�) В) C(s) + 0 2 (g)- CO2(g) С) CaCO3(s)- CaO(s) + CO2(g) -:, .\ &�.Л-1::_ � , \1\... D) С!-!3ОН(i) + СН3СООН(f)- C!-!3COOCH3(aq) + !-!20(1) _ 15) А 1.0-gram piece of zinc reacts 1vith 5 шilliliters of HCl(aq). \Vhich of 1l1csc conditions of coпcentration and tempcrature \\'ouid produce the g,·eшest ratc of rcaction? @ 2.0 М HCJ(aq) at 40. 0 С) 1.0 М HCI(aq) at 20. С D) 1.0 М HCI(ag) at 40. 'С С 0 В) 2.0 М HCl(ag) at 20. С _16) _17) _!R) 0 \\'hich statement best explaiлs the rolc of а catalyst in а cheшical reaction? А) А. catu!yst is addcd as an additiona1 rcactant апd is coпst1mcd but not rcgcncпit1.;d_ В) А cataJyst Jimits the amount ofreactants нscd. С) А cataiyst changcs thc kinds of products prodt1ced. � catalyst pro\·ides an altcrnatc reaction pat/1\\·ay that rcqt1ircs _Icss activatioл спсгgу. \.\/hich phase change represcnts а decrcase in entropy? А) solid to Jiquid В) liquid to gas [\'СП ·- tlюLJgh thc proccss is eпdo!l1ermic, Л) tcndcпcy tO\\'Jrd !css cncrgy 13) а tcndcлcy tO\\'JrcJ !css cntrupy ,1_ ·'-r;;) gas to liчuid D) solid to gas SПО\\" сап st1blime. \VhicJ1 tспdслсу iп лaturc accoLJnts for t!1is pi1ase ch:.н1;L:'? @ а tсшkпсу tO\\·aг(J greatcr cпtropy D) а tendcncy tO\\:arli grc�Iter cncr�y 1 _ 19) Given tl1c b,1\anccd cqнation: 2 KN03(s) + 34.89 kJ Н О к+(аq) + N03-(aq) Vv'hicЬ statcшcnt best dcscribcs this process? С!) В) С) It is cxothcrmic and cntropy dccreascs. D) It is cxothcrmic алd cntropy increases. It is endothcrmic and entгopy increascs. It is cndothcп11ic апd entropy decrcases. Qнcstions 20 and 21 rcfcr to thc foHo\ving: ln а lalюratory cxpcrimcnt, 10.00 grams of an unknown solid is addcd to 100.0 niillilitcrs of wзtcr and thc tcmpcraturc of the rcsulting solнtion is mcasured ovcr scvcral шiпutcs, :is rccordcd in tЬе tаЫс belo\v. Change in Temperature During the Dissolving of а Solid Data ТаЫе Temperature Time (minutes) ("С) о 0.5 1.0 1.5 24.0 28.5 31.0 2.0 34.5 41.О 2.5 45.5 3.0 46.5 ) 1.,1 ·, ✓- . ,,, ,, . 't / J ,, /\) ;} 't) 1 ю 1 О _20) 0.5 1.0 1.5 2.0 2.5 Time (minutes) 3.0 35 1 (а) Оп the grid provided, шark ап appropriate scale on thc axis labelcd Tcn1pcratшe ( С). ' An appropriatc scale is onc tlшt ailOv\:s а trcnd to Ье seen. (Ь) Plot thc data fгош thc data tаЫс. Circle and coпnect the points. 11 EXAMPLE:� 0 _21) '' Givcn t/1c fo!Jowing statcmcnt аЬонt t!1c laboratory cxpcrimcпt shown: -"\Cu,rь� -tt'-\. '5\ Tlic LJпkno\-Vn soJiJ is cithcr sodium hydroxidc or lithiuш bromide, and bot]1 of tl1csc compounds dissolvc in \-vat�\ cxo1l1crmically. (а) (l1) Nu.0 \� . Expluin ho,v tJ1c cxpcrimcnla] data support thc slutcmcnt. С"i,Q � �-\v 1._ � �\Ах... kc,__,f .. E Stulc spccific information from thc Heats of Reaction at 101.3 kPa and 298 К chcmistry rcfcrcncc tablc to support tl1c statcmcnt. !'-\ С\_о 1-\ _22) LL � v L\tг -1\'-\. s \ VI. ➔ � \\ -1\- Q) '" с: ш ·.;:; = i-\µ_�t(- �1-\ 14 ,l t \·t...1 Given the potential energy diagram and the equation below: 0) \/О� Ь - - - - (2) - - 7 - )N �'-\ �о� - л� ::: с9 -s. �� · \ (\ ,..,. \ \ d 7 �\_,,l - � ... ::. ,.J•t>� +- - - - '- а в t - - - - - - - - (4) - - 1/ (3) '---'-'--'--",<- - - - - ( 1) Reaction Coordinate 2C(s) + H2(g) + 227.4 kJ - C2H2(g) _28) _29) _30) Bascd оп the given information, ho\v many moles of с 2н2(g) are produced if 682.2 kilojoules aгe ·absorbed? \� = � dё)[ .� \�_ t.oi"'ё). d 'к� 1- ::: �� L0 �\ :J. Dcscribe ho\v the potential energy diagram sho\vn \Vill change if а cцtalyst is addcd. l��