{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Exam 3 Key - CHEM 1123 Fall 2006 ‘l EXAM 3 CHEMISTRY 1123...

Info icon This preview shows pages 1–7. Sign up to view the full content.

View Full Document Right Arrow Icon
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 2
Image of page 3

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 4
Image of page 5

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 6
Image of page 7
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: CHEM 1123 Fall 2006 ‘l EXAM 3 CHEMISTRY 1123 November 14, 2006 Name: Rules: No talking, trading Calculators, No explosive flatulence, No use of any materi Is except pencil and Calculator, Place answer on N08 Form. 1. What IS the 2correct Kgp expression for 083[PO4)2]? A) [Ca3+] [P04 1 41%) ‘ élcaails ] [P04 3;] C‘tg(?a%b _._.._~:~ EC“?!- 1 Ll. [Ca “ [P043 ‘21 D)[Ca:+l:P 1P 1 1041 K5? ._ {CP 3 8704 3 EllCa *3] [P01 2. At 50 °C the solubility of lead sulfate is 1.5 x 10-4 M. Calculate the KSp at this temperature;3 . 1+ +30 ‘ port-3x10": {9680f "fie—— Olh ' 5* .22 x1o': S )1.5><10‘4 -LZNO ‘51.: one x 1010 K312" E)1.4x10'“ 2 2; m'c‘ 3. Calculateathe molar solubility of Pblz. (DP's Helper: for Pblz, K5p = 7.1 x 10-9) A)1.9x1o“ 2 214» L?" B)1.5x10': mil 12;” SE 4 ’: 08.4x10'5 a)» r“ 1' D)4.'38x10 K31” " VOTES/L L ’S {5' @12x10‘3 ‘3 (2’53 3' ‘53 I 31"” -3 3 ’5- l , 749% 4. Calculate the molar solubility of calcium carbonate in 0.10 M Na2003 (DP’s Helper: for calcium carbonate: K5p = 2.8 x 10-9) @28 N108 4r; C ‘ B)2.8><10"1-]\L11C05 re 7/5152“: ®: C 0.10 _ Dl2.8:«10‘9 QaC-OB :3 a. +CO1° .8x '6 1+ . - E)2 10 [496) 4., 25,62, ESQ); 1 12,? we“? ' 9 (.010 5% CHEM 1123 Fall 2006 5. If 555 mg of MgCI2 (95.2 g/mol) is added to 250. mL of 0.015 M NaF will a precipitate form? (DP’s Helper: KSp for Mng = 3.7 x 108) Yes, because 0... < Ksp. fl AYes, because Qip > K... M Cl; Ql‘. (qr: 53—9 Ma r; {ZN-1C1 No, because Qip < Ksp. 3 3)) I'd: 52:23:: 8::::::_ Mafz $1:- Mart .{ ‘2/f’ Its? szffiflt‘k) Q1» .11. Mflwg @ngzmfigl‘f 223.5%(3’1' («Ma )ZL/J— (mmmaq “I 39.1%, (9.2.51... ‘0 t' j" (9:0tS‘RA @‘VD [1372955]{O.0n31l152¢tfla ‘9??? 7st 6. What IS the [Zn2 ]' In a solution that Is 0.21 M in [Zn(NH3)4]2 and has ammonia concentration of 1. 2 M? (DP’ 3 Helper: Formation constant for zinc complex Is 4.1 X 108 ) Q; 13:18—10 2:.” r we. 2:? 2:“ W635 c) 7.0x10‘3 {:«(W‘bfis O .2" D) 2.3x109 ‘LC 1 q _ -.. fl? @ 2.5x 10‘10 __ IQ [hygg 2. Z. LDC/'0 Problems 7 and 8 are together Consider a beaker containing 500 mL of solution. The solution contains a silver complex with ammonia [Ag(Nl—i3)2 ] of concentration 0 7 M and ammonia concentration of 0.2 M. (DP 5 Helper. Formation constant for the silver complex Is 1.6 X 107 ) 1. [l ”t /( lNl‘H :3 ”(B'CN‘AE 7. What is the [Ag+]? A) 33-1113? K: 1 {Await @121? {Aammt a E) 1.6x10‘7 ' 014 . ‘ .__(. CHEM 1123 Fall 2006 W 8. How many grams of K! would have to be ad d to just begin the precipitati silver ion? (Ups; 5 Helper: Molar mass of KI 16 Imol; Ksp for Agl is 8 5 X 10 (was 3019‘“ J @ 6.3‘947x10 I3)4.‘30x10 A3: :3 fidflf’f g p _ _ @750 8; {13-3183 Q9 LhQJTXEI-lt— (I07Xr0 >£I3g . ,Il E) 7.8x10‘11 . 33“ Problems 9, 10, 11 are together Consider a beaker containing a mixture of Zn2+ and Ni2+, 0.02 M each, Thad and starts adding C032— (Ksp for 24003 is 1.4 x10‘“; Ksp for NiCOa is 6.6 x10 ‘9) 9. What carbonate concentration is needed to start precipitation of an ? A 1.9’4x10 ‘Vt’ 0”“ a; 33x10 fig“ IUD-:3 Q)? 7 ”m ' 0" Ito c 3.0x106 ea; Lil—L2 gm) 7.0)(10‘10 - (C “3 o M“ E) 1.4x10‘11 10. What carbonate concentration is needed to start precipitation of Ni2+ 7 A) 1.94x10 m we; @33x10‘70 90: Egg, J 66, x30 -7 ).30x106 . 6'6 - 34:0— _ ~31 0) 7.0x10 (03 l?— .. . ‘1'— §$>io E) 1.4x10‘11 [ 0‘44» ' é). When Ni: begins to precipitate what is the Zn2+ concentration ? 4.‘:2x10 7 _ 3.4 3y 2).0x10‘2 fgmflfwg, 3 *v It We C) 1.0x10? l {Mom D) 3.3x10‘ at (3-3 0 B: I If E) 7.0xm‘9 8.3““ 1 K -o’ [#> 246.2%??? CHEM 1123 Fall 2006 4 12.What is the Azide (N3_) concentration in a solution saturated with Pb(N3)2? Ksp lead azide is 2.5 x 10.9 H N _ A) 2.5x1of mars. —...-—;=- W. -r 2 3 B) 3.5x10‘56 S l a) 3 C) 1.36x1o_4 LENS? : 50/8) 5 “t3 D.) 8.55X1O . _ @1-71X10"3 s : ‘63qu ‘l 55 cm 25 = "Mo 13. Consider the follow in equilibria involving the main ingredient in concrete: Calcium carbonate. CaCOam H Ca2+ + 0032‘ cosz‘ + H20 <—> Hco3‘+ OH— 2H20 <—> H30+ + OH— Which one of the following statements is true regarding the effects of pH on solubility: A) Lowering the pH causes the hydroxide concentration to increase Lowering the pH causes morecalcium carbonate to precipitate. Lowering the pH causes the bicarbonate concentration to increase Raising the pH causes the carbonate concentration to increase ) Raising the pH cases the bicarbonate concentration to increase 1 4. UPS old kitty, Braindamage can’t pee. The tube from the bladder is blocked by MgC03(s). Which one of the following should be fed to kitty to dissolve the soii and sav Braindamage. 03?; ll-be $12.: éabb'xL-BQN': Mafia/mt L—ML to L39] A) MgCOs B) H20 . N82C03 Ascorbic Acid E) Preparation H 15. Identify the Lewis Base in the following equation. Fe3+ +6 CN— <:> [Fe(CN)6]3+ A) Fe3+ B NH3 N— ) H20 E) not an acid-base reaction CHEM 1123 Fall 2006 5 16 What Is the [SCN ] In a solution that initially only contains complex [Ag( (SCN)21 at 0.25 M ’? (DP’s Helper: Use ICE method; Kf= 2 7 x 1D8 ) 81:31; 1:6 +280) 17““)?- (3)27x10'8 0088 “(C D)188x10‘8 Kg"; ( > 5 7-17“? E) 2.'0><10'10 x (2“) 6i 1,? . '5 .L ‘ 1x fife“ 3 ”56' he?” uh {SCM'E lamp //2 17. How many of the following processes would you expect to isbe spontaneous at 298 K /‘ and 1 at / fisolving salt (NaCb In water composing water to the elements DP falling from an airplane (after being pushed by Helen) leaning your room l ) Ice melting )0 (ie none of them are spontaneous) )1 B)2 )4 Problems 18 19, and 20 are together. 18. Given the following standard molar entropies, calculate AS" for the reaction in J: ITI CH-Ilg) + 202(9) -I CO2(Q) + 2H20(Q) S°Jlmovi 186.2 205.0 213.6 188.7 (IQ—5.2 5,5”: 213.19 f 21113193 - 0% ,1 1 20.07) B) 11.1 D / C) 793.5 A3 2.0.7, D) —11.1 E) -—193.9 19. Given the following heat of formation, calculate AH° for the reaction in kJ: CH4(g) + 202(9) ——> 002(9) + 2H20(Q) AHf°lemoleK —74.8 0.0 —393.5 —241.8 A) ”560.5 _ . B) -7101 (figgefigzwfl »- ( ~Wfl) &—709.8 —802.3 0 - . E) —241.8 M " 9302'“ CHEM 1123 Fall 2006 6 20. Use the answers in Problems 18 and 19 to calculate the free energy change for the same reaction in kJ at 25 0C. (DP’s helper: AG° = AH° —TAS°) CH4 (9) + 2 02 (Q) —* 002 (g) + 2H20 (9) A —776.3 x a _. . .— 2 .. 0,0052. = 3—502; M3 3023 LWV 3 00. - E) —560.5 21. Which of the following reactions leads to an increase (+) in entropy of the system? H4C| (s) —> HCI (g) + NH3 (g) ) CH4 (9) + 2 C02 (9) —* 002 (Q) + 2 H20 (I) C) CaO (s) + 002 (g) —. CaC03 (s) D) 4 Fe (5) + 3 02 (g) —, 2 Fe203 (s) E) 2 Hi (9) + Clz (g) —> 2 HCI (9) + I2 (8) 22. The following reaction is endothermic (AH>O): 2 803 (g) ~+ 2 802 (g) + 02 (g). The reaction is (DP’s Helper: AG0 = AHfl — TASO) A) spontaneous at all temperatures. B) non-spontaneous at all temperatures. ‘1— ‘“ TOG C) spontaneous at low temperatures. fl spontaneous at high temperatures. 23. Given the standard free energies of formation, calculate AG". in kJI for the following reaction at 25°C. 2NO(g) +Br2(l) ——> 2NOBr(g) AGf°lemoI 86.6 82.4 A -7.3 7/ . _ {at 1 ”‘3. 31-115 ((52% LL \ (T C)341.1 D)11.5 @134 24. Calculate AG“, in kJ, for the following reaction at 25°C ifthe value of Keq is 6.1 x 1053. A 27.4 326 c 27.4 r ; _. Tfixfl D; 3.22 AC3 ‘ R E) -326 CHEM 1123 Fall 2006 7 25. One day in class DP mixed sodium bicarbonate and aqueous acetic acid together. There was this big fizz but after a while nothing was happening. At this point in time (scene 2 as DP likes to say) AG for the reaction is: DP is trying to trick me, for a reaction at equilibrium the free energy change is zero ) The free energy change is positive C) The free energy change is endothermic D) Overall, free-energy leaves the system E) Overall, free—energy comes into the system Cheat Sheet KbKa = Kw Or pKa + pr = pKw =14 [H30+][OH_] = Kw = 10‘14 pKa = -logKa pH = -|og[H30+] [A’] [HA] pH : pKa + log AH " : Z VPAH; (Pr DdHCIS) — Z VrAH; (Re ac tan ts) AS = Z VPS"(Pr oducts) — 2 12,8” (Re ac tan ts) AG" 2 vaAG} (Products) — Z vrAGj. (Re ac tan ts) AG" = —RTln K R = 8.31 J/mol-K K = C° + 273 AG0 = AH" — ms" ...
View Full Document

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern