Exam 3 - CHEM 1515.007 — 0011 Name ‘_ Exam 111 w . -9...

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Unformatted text preview: CHEM 1515.007 — 0011 Name ‘_ Exam 111 w . -9 John 111. Gelder TA's Name iii". f tif'iif' April 7, 2010 r. " Section ___1__ INSTRUCTIONS: 1. This examination consists of a total of ll different pages. The last three pages include a periodic table, a solubility table and a table of equilibrium values. All work should be done in this booklet. 2. PRINT your name, TA‘s name and your lab section number now in the space at the top of this sheet. Di) NOT SEPARATE THESE PAGES. 3. Answer all questions that you can and whenever called for show your work clearly. Your method of solving problems should pattern the approach used in lecture. You do not have to show your work for the multiple choice or short answer questions. 4. No credit will be awarded if your work is not shown in 3. 5. Point values are shown next to the problem number. 6. Budget your time for each of the questions. Some problems may have a low point value yet be very challenging. if you do not recognize the solution to a question quickly, skip it, and return to the question after completing the easier problems. 7. Look through the exam before beginning; plan your work; then begin. 8. Reiax and do well. Page 2 Page 3 Page . ~. 7-». I, 5 g: ’ SCORES l (21) (20) 220} CHEM 1515 EXAM III (6) PAGE 1. Write the chemical formula(s) of the product(s) and balance the following reactions. Identify all products phases as either (g)as, (l)iquid, (s)olid or (aq)ueous. Soluble ionic compounds should be written in the form of their component ions. 3) HClO4{aq) + KOH(aq) —> it 34!; qu’Qw / b) HC2H3Oztaq) +(CH3)3N(aq) —> "(I u, {3 w A“ a a? ‘ 3 heat?” (53 H3 “@533 (4) 2. Write the ionic and net ionic chemical equation for 1a). Ionic equation HEW NWng 3» thq) + Maggy") iv Kim / fr 2 L‘\ Net Ionic equation l ., N . H Q1341} “i” "" Witty“: , ,1, pg (31) 3. Calculate the pH at) 0.335 M HC4H702 ' ,3 A 4' a m 1‘13“ < J 0» ,r + I/ m 9" x v 7 i 7L C‘i H7 0’ Ki :2 16x (0%; C“ .3 91H 1% 2 .1 A; 3’4 Ma 7/ ‘ A 5 “J O l») _j H C ‘ ,, z , g i“ X “t *- : (x3 (x) r a...) m X ‘3: if}??? 3’35 ’ ‘ m r,“ "A \ x): 563% 44 m >1 2 9a a??? we" : (i4 it Hi"? ‘3 :' CHEM 1515 EXAM III ' PAGE 3 5P 0: F? b) 0.800 M 3910 | CN‘ + H070 1:1“ MW m H “ \ I [5W 8 mo C ’x I +)< +2< E 0g’y‘ "’ 0‘”- (9-H Kw __ [o’w .. Kb“ 10L ’qguoflajflflo poHanM , flme—mVsufl c) 0.65 M HC7H502 (benzoic acid) and 0.55 M KC7H502 a)» 0- a W 3407 54509 + Hog/sf H30 7%? M; I 9 (Qfimx k if“; 053%»: [C5 AX + X 4 x ’ a [03% OM 9‘33” ‘9? lav-30136: ' 0 (H (:7 05533 t : £55+X? ((QS’X 425303000! ’9‘: f; A j \ r 47:“ : afis‘gg: 1mm vs CHEM 1515 EXAM lll PAGE 4 Short Answer: (20) 4. In the laboratory a student is going to perform a titration by adding an aqueous solution of NaOH (in a buret) to a given volume of an aqueous solution of HCl (in the flask). The concentration of the HCl is “K 0.450 M and the concentration of NaOH is 0.350 M. a) Write the balanced chemical equation that describes the neutralization reaction that occurs in the titration. (2) Nero HQ «> only, n b) What is the value of the equilibriu a n1 constant for this reaction? (2) K m " r V: M c) The student is asked to pihet halfof the solution into the flask, calculate the pH of the solution in the flask before the adding the NaOH solution. (2) 6’ g A: 3‘ I "\i I." g \ ; Hogans; - t , d) How many moles of HCl are present before the titration is started? (2) a . 3, , m 'K r : ‘- x‘ .-. , a ’9‘ ii "" "f h I ‘ G ‘ O J: t O {eh “; mnwflf 2 IE} “it; 1 .7 a ’ ., L; ,r e) How many moles of NaOH are required to reach the equivaleneewnoint’oi titration? (2) f H .m- V g, x V " T: [h 5x :0 “Ma f) What is the pH of the 'solut—ionfiinthe flask atflthe equivalence point? (2) . a *‘M 1 if" a g) What is the pH of the solution in the flds" after adding 5 ,00 ml. of NaOH beyond the equivalence point volume? (2) E 5% me?” i f M N a H w 1; ‘ v: J "2- ": t I 7 g ‘: ‘ ll‘lml c @733; l; {3174? I" t (a; 75!.) IL ' [9") a! ' a,“ if) WM I“ 2/ / 9 ~ V for, :ng g afi‘gfiéfi ~ H5“ \fj Q IE_Q“7* h) Draw a graph (titration curve) of pH versus volume of NaQH added usingvth‘e thisvproblem and your knowledge of titration curves. Be sure to clearly label those points on the titration curve that you get from the questions in parts a —— g. (6) it; 1’ _,.-—-___...._.., _.,m.7.. it / / i- ,. 1/ A if CHEM 1515 EXAM III PAGE 5 Print the letter (A, B, C, D, E) which corresponds to the answer selected. (39 points) 6. Q1 7. \1 8. ~_ 9. 10. E. 11. 12. 13. (9 4. D 15. E 16. E 17. 3. ONLY THE ANSWERS IN THE AREA ABOVE WILL BE GRADED. Select the most correct answer for each question. Each question is worth 3 points. 1 6. Which of the following reactions does not proceed significantly to the right in aqueous solution? A) NHfiJ—FF “'"WN + B) W C) Hezngo2 + H20 # C2H3Of + H3o+ D) WW E) W 7. Given a solution of H2C03: I. H2CO3 K8», 1: n. HCO3— (M 1/90; ‘ III. C032— Which represents the specie(s) that defines/controls the pH of a 0.100 M H2C03 solution? A) I only E) II only C) III only D) I and II E) 1, n and In 8. Which of the following is the strongest Bronsted—Lowry base? ‘ / A) C104- B) C2H302— C NO — A _, 1 :4 fl f g A” g r ) 3 \A $21M 1“ 7‘1. “2:3‘ ” 3W D) 11304w b \l 6%: a “:2 , W 1 x? {‘5‘ ‘ R“ “fife” __ (MA é; Add; A», l I {,5}, V E) CN W ’ nee-1‘ bagel, CHEM 1515 EXAM Ill PAGE 6 9. When 0.125 mol of N2 and 0.376 mol of H2 are placed in an evacuated LOO—liter flask, the reaction represented below occurs. N2(g) +3H2(g) r—é 2NH3<g) After the reactants and the product reach equilibrium and the initial temperature is restored, the flask is found to contain 0.0225 mole of NH3. Based on these results, the expression for the equilibrium constant, Kc, for the reaction shown above is A K __&9_2;2.5i_ ; “7( ) c’(e.125)(0.37§)3 f’ B K _ (0.0225)2 ( ) 0‘ (0.103)(0.354_)3 C K _ (0.0225)2 ( ) 0“ (t).114)(0.342)3 10. After the equilibrium represented in Question 9 is established, same pure H2(g) is injected into the reaction vessel at constant temperature. After equilibrium is reestablished, which of the following has a lower value compared to its value at the original equilibrium? (A) Keq for the reaction a,“ v r t (B) Thetotalevolume in'the reaction vessel. M9”) Jr”! <’ (C) Theamount—of—ng) in'the “reaction vessel. 61 (D) Iheamount‘of N2 (g) in the reaction vessel. ' (E) The amount of NH3(g) in the reaction vessel. ll. Which of the following changes alone would cause a decrease in the value of KC for the reaction represented in Question 9? (NOTE: AH°Dm = —91.2 id 111014) B) Increasing the temperature C) Decreasing the volume of the reaction vessel D) increasing the volume of the reaction vessel 3W ~>A) Decreasing the temperature CHEM 1515 EXAM III PAGE 7 12. The Ka for a particular weak acid is 1.0 x 10-5, what is the percent ionization for a 0.100 M solution of this acid? ,1 V , _. L“ . A) 100% it ' B) 10.% C) 5.0% D) 1.0% E) 0.010% NH3(aq) + H2$(aq) '5‘“: NH4+(aq) + HS~(aq) @QCQX 13 The reaction represented above has an equilibrium constant equal to 1 0 X 10 Which of the followmg can be concluded from this information? hire V” ~>A) NH3(_aq) is a stronger base than HS‘(aq) B) NH4+(aq) is a stronger acid than HZS(aq) Ilieconjugate base of The equilibrium constant does not change with an increase in temperature. FfThe pH of a solution containing equimolar amounts of NH3(aq) and HZS(aq) is 1.0. 14. Which of the following solutions will have the lowest pH? A) emotion B) WW) ( C)0.1MHCN(aq) ‘ ~>D> 0.1 M chnsozoq) 6 W ' E) 0.1~M»H(-}2H§@§(~a . . 15. All of the following species can function as Bronsted—Lowry bases in solution EXCEPT (1501420 (8) Cl’ (C) 82’ (o) Hco; (E) CH3NH3‘” 16. A 0.50-molar solution of a basic sait, A‘, has a pH of 9.00. Calculate Ka for the acid, HA. “05'0" 10—10 1 ' a“ t or— , 005:9?” B) 2.0 x 10—10 l n V H ‘ " Kaye 332:. 5' 6 a i x (C) 1.0 x 10—9 ‘o c (D) 22 x 10'5 m x M 7» x n. (E) 1.0 x 10‘5 a q? mgr: CHEM 1515 EXAM 1H PAGE 8 17. What volume of 0.150 M H2804 is required to neutralize 16.5 mLs of 0.200 M NaOI-l? @110 mL & 6155. 6 6 a)??? 16.5 mL 9m) 22.0 mL (D) 33 .0 mL (E) 44.0 mL 18. KP for the reaction C2H4(g) + H20(g) # C2H50H(g) graffiti—l do (575‘ 9 is 2.0 x 103 at a given temperature. A reaction vessel has a mixture that contains 0.00400 atm of C2114, 0.0075 atrn of H20 and 0.067 atrn of C2H50H (A) the reaction proceeds left to right because K1315 greater than 1; I (B) the reaction proceeds right to left because appreciable amounts of all three substances are present; ,3) (C) the reaction proceeds right to left because Q > KP; (D) the reaction proceeds right to left because the partial pressure of CZHSOH is larger than the partial pressure of C2114; (E) the reaction proceeds left to right because Q < KP. 3‘ ma as -xirt‘rf: MC d z ’ f“ CHEM 1515 EXAM HI PAGE 9 IA Per10d1c Table of the Elements mm 1 1 1.008 ILA . 34 567890 . 6.94 9.01 10.81 12.01 14.01 160019.00 20.18 1112 131415161718 08 REESE! 229924301113 IVB VB VIB VIIB VIII 7 IB 1113 26.98 28.09 309732063545 39.95 19 0 21 " :' 5 ‘ 26 -' - '- 31 ' 32 33 34 > 35 f 36 aaaanamaamwaaaaaaa 39.10 400844964788509452005494 55.8558.935869631556538 69.72 72.59 74.92 789679908380 37 3 39 ' 40 142 43 44 45 ‘ 48 49 0 51 52 53 fifilfififihfifififififlhfifllm 854787628891912292919594 (98) 101.1 102910641079112.41148118.7121.8127612691313 5 73 74 5 76 77 78 8 8 ‘ 82 83 ’ ’f 86 6.1.1 61 6. 16 .. 6 11 14 .6 6... 132.9 137313891785 180.9183.8186219021922 195.1 197.0 200.6 20442072 2.0 (209)(210) (222 87 g 8 89 105 106 ' ' ' hmmlll (23) 226. 227.0 (261) I (262) ' (263) 8 9 60 6 . 62 63 f 64 ' 6 ' 7 6 . 0 ' Ce PE Nd P1218111 E11 Gd Tb Dy HeEr Tm YbLu 140.1 140.9 144.2 g (145) 150.4152015721589 625 164.9:67.316831731917511 90 i' 92 93 j 94 9 ‘ 961 97 _ 98 991001001013 TE: ' Pa U Np PuAmCmBk Cf E8 FmNEéNe LE 232.0 23.0 238.0 237.0 (244) (243I (247) i (24 . (251) i (252) . (257) (58) , 29) . 60 2 3 U1 Lanthanides Act'mides Useful information pH = —10g[H+] pOH = —16g {OH-1 pH + pOH = 14 Kw = 1.00 X 1044 KP = KC(RT)AD 113 11m 0 9 In 1 = _ R T2 — T1 —b:1:\/ b2 — 430 8122*?“ for ax2+bx+c=0 CHEM 1515 EXAM III Acetic HC2H302 1.8 x 10-5 Ascorbic HC6H706 8.0 x 10—3 Arsenic H3AsO4 5.6 x 10—3 1.0 x 10-7 3 .0 x 10-12 Arsenous H3ASO3 6’0 X 10—10 Benzoic HC7H502 figs/mt: Butanoic acid HC 41-1702 Carbonic H2C03 43 x 1057 5.6 x 10-11 Cyanic HCNO 35 x 10-4 Citric H3C6H507 7.4 x 104 1.7 x 10-5 4.0 x 10-7 Formic HCHo2 1.8 x 10*4 Hydroazoic 111.13 1.9 x 10-5 1 Hydroeyanic HCN M Hydrofluoric HF 7.2 x 10—4 Hydrogen chromate ion HCrO4’ 3 .0 X 10'7 Hydrogen peroxide HZO2 2.4 x 10‘12 Hydrogen selenate ion HSeO4' 2.2 x 10’2 Hydrogen sulfate ion H804" 1 .2 x 10-2 Hydrogen sulfide H28 57 x 10-8 1.3 x 1(r13 Hypobromous HBrO 2.0 X 10‘9 Hypochlorous HClO 3.0 x 10’8 Hypoiodus HIO 2.0 x 10‘11 Indie HIO3 1.7 x 10-1 Lactic HC3H503 1.4 x 104 Malonic 1129311204 1.5 x 10-3 2.0 x 1045 Oxalic H2C204 5 .9 x 10-2 6.4 x 10—5 Nitrous HNO2 4.5 x 10-4 Phenol HC6H50 1.3 x 10-10 Phosphoric 14131304 7.5 x 10—3 6.2 x 104 4.2 x 10-13 Paraperiodic 115106 2.8 x 10~2 5.3 x 10-9 Propionjc HC3H502 1.3 x 10-5 Pyrophosphoric {{4on 3 .0 x 10-2 4.4 x 10"3 Selenous IrIZSeO3 2.3 x 10—3 5.3 X 10—9 Sulfuric H2804 strong acid 1.2 x 10‘2 Sulfurous 112803 1.7 x 10-2 Tartaric H2C4H406 1.0 x 10.3 E2 DESSOCIATEON CONSTANTS FOR BASES AT 25°C Ammonia Hydroxylamine V Aniline Methylamine Pyridine Trimethylamine Dimethylamine Ethylamine Hydrazine PAGE 10 CHEM 1515 EXAM Ill PAGE 11 Solubility Table Solubility Exceptions soluble none soluble none soluble except Ag+, Hg22+, *Pb2+ soluble except A g+, Hg22+, Pb2+ soluble except Ca2+, Ba2+, Sr2+, Hg2+, Pb2+, Ag+ insoluble except Group IA and NH4+ insoluble except Group LA and NH4+ insoluble except Group IA, *Caz+, Ba”, Sr2+ insoluble except Group IA, HA and NH4+ soluble none soluble none soluble none *slightly soluble ...
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Exam 3 - CHEM 1515.007 — 0011 Name ‘_ Exam 111 w . -9...

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