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A_B Practice Test6_key

A_B Practice Test6_key - CHEM 1202 Sect 1 Spring 2010 EXAM...

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Unformatted text preview: CHEM 1202 Sect 1 Spring 2010 EXAM 2 Acid/Base Equilibria Dr. Kolniak FORM 1 IMPORTANT: On the scantron sheet fill in your name (LAST name first) and ID number in the box and bubble in the corresponding letter and number. Ask a question, if you are not sure about what to do or if you are confused about the content of the problem. Select the very best answer (5 pts each) Constants: Kw = 1 X 10'14 1. What is the pH of a 4 x 10'2 M HNo3 solution? pH = 1.40 ** pH = 12.60 pH = 2.00 pH = 0.50 e. pH = 7.00 (Pl—‘1'; wizard} {2WD}? :3 LE??? 9.0.693 at, 2. Choose the Weakest acid from the following pairs: Electronegativities: Br = 2.7; S = 2.4; Cl = 2.8; 1= 2.2; H = 2.2 Ctgewwtw 3: ‘f‘t’ Egg?" . .2 3.. giver H1 HBr04 {H104} a. HCl HBr04 H2803 b. HCl H104 H2804 0. H1 HBr04 H2804 d. HI H104 H2803 e. * HCl H104 H2803 3. Given the following acids and their associated pKa’s, which is the strongest acid? a. H28 (pKa = 7-1) 190.3% ’1” gkfit b. C13C00H(pKa = 0.7) *** c. CH3C00H(pKa = 4.7) d. NH4+ (pKa = 9-2) e. H2803 (pKa = 1.8) 9995‘s» 99‘?” P“ 6&3 Wit? a. b. .m .0 Which of the following mixtures would cefifititute a buffer solution ? l ”W jug: 0.1 M NaOH + 0.1 M NaCl inn, 0.1lequ§1+0.1MNa%-fllfi‘f 7 , Wei W M 111. 0.1MNZEiEOfi 0.1MH2d53 EM gaff? g“? g 51% ESE!“ 0.1 M HCIO4 + 0.1 M NaClO4 I only ’7\ f? \ ll only Nag No Me) NQw%mi fimiflmg Ill only *** Ill & TV only I, III & IV only N0 an at, an» ”animal What is the Ka of a 0.15 M weak acid (HA) solution that has a pH = 1.8? Ka=1.66x10'3 @stgfly x X Ka=7.14x10'4 ensue 6mg; ofitgfi“ rpfifi—hg % ..,,‘?lf%“ H30+<aq>+A'(aq> NETS 1 i; W 55m: 5 H%n*'32x,: (Lotta? HA(aq) + H200) Ka=1.86x10'3 ** ,3 Ka=216 ea g %0?3 f AT 3 m “JLQ ’3 @ i W‘w.mfl _Q_ :1 E 2. '3 éflé f; V v W ‘__ . . m“ > -4 M.“ W 1%. Ka=4.63x10'2 {Mag or WW Consider a generic indicator, HIn, that is a weak acid. The acid form, Hln, is yellow and the conjugate base? In', is blue. Which is the correct answer for the color of this indicator if excess NaCl is added to the solution? if“ a} Hln (aq) + H20 (1) at») “if The equilibrium will shift right and the solution will be blue. 111' (aq) + H30+ (aq) The equilibrium will shift left and the solution will be yellow. The equilibrium will shift left and the solution will be blue The equilibrium will shift right and the solution will be yellow. Nothing *** Newtrml gm...” what‘s mi“ QM W4 What is the pH of a 10.0 M anonymous acid, HA, solution that has a Ka = 6 X 10'5? HA <aq> +H20<1> H30+<aq> + Memo 10 M X is pH=2.78 pH=3.22 pH=1.61** ; , :2 ">61. ’§ 2~ pH=2.11 Kg» fl f9 ti”) tr— >4 T— om art-M pH = 4.22 w 9999‘?» .0 09.0w» 99.0979 09.0.65» On average the pH of some stuff is about 3.8. What is the [H30+] at this pH? 631x10'1‘M vi ”WI s. 2.24X10'ZM @ng E?“ W ”2. \ffiésmci 3.7lxlO'3M 1.58x10‘4M ** 4.28x10'4M ‘éi‘i What is the pH of an8x10 MKOH solution? pH=10.903 *** W353“ “is“; W” s: “swim .pH=l0.000 32% Mm Wig” r waif; pH=8.038 W . pH=7.000 pH=3.097 Which one of the following statements is the correct definition of a Lewis Acid? an electron acceptor ** i— "B‘ s R an electron donor . if} Q a” Q 1% “WW 1ncreases OH concentratlon + donates a H s - + combines With or accepts H A solution of weak acid is made at a concentration of 8 X 10'2M with a pH of4.2. What is the % Ionization for this weak acid in solution? u. «is is ’alwfi “ ' N 99.921% i=5 ; 25.5052 f» ?; I: 0.079% ** M ‘E‘klmz g 3 fits 52.5% 344% t 47.5% V 0 «gig n- a? t: i)“ ‘ ”813% 1.00%) EVE”? m 3 i.“§i:ss"3 f9: . €37 2 Which of the following salts results in an basic solution when dissolved in water? II NazCO3 W Fpfifiifi fizwffi w bar III. NaCHgCOO 4;»: $94M; {4 @W is? with? IV. NH4Br £22m: MA sir: I only II only III only IV only II & III only ** a t 3 13. Calculate the pH of a bufler solution that is 0.5 M in carbonic acid (H2CO3) and 032%, M in sodium bicarbonate, Na HCO3? Ka (H2C03) = 4.3 x 10'7 H2C03 (3C1) Av— H+<aq)+HC03'<aq) a. pH=6.66 {9‘ g” @E b. pH=6.16 . at“? {o :2: i} . H=3.33 1“ :- Q‘: ’ .. \ .p m M. g awn: x M d. H=5.47 P @.§” flag... 6. pH=6.57 *** fl “K a: §a%3?3~ we” 7:... ti: Ema—2, tasty“? 14. What is the [0H] for a solution that has a pH= 8.2? i.- a. 2.75x10'4M . m elm 6 E mt ”i a W b. 1.58x10' M ** -9 C. 6.31X10 M §©W31W~ @§‘%’ 2., Q“: “a d. 1.00x10'7M e. 3.03x10'3M .. 3‘3 gm"? 3 5:: w ’2: at. “$E‘2va49 15. What is the pH of a solution after’é ml of 0.1MHNO3 reacts with6ml of 0.1 MNaOH? a pH= 3 V V t» V ' @3%Mv¥k§§§% @afis‘mM aka/4,.“ b. pH=Sg \J c. pH= ($.84 ** ‘9 almmfl Win ibifit e pH= 7.00 MM 2.; Ettig '3 6.54% My; $34“; thgi’i 16. What is the pH of a 0.5 M sodium bicarbonate, NaHCOg, solution? Ka (H2003) = 4.3 x 10'7 HCO3' (3(1) + H20 (1) "—35 H2CO3 (aq) +OH' (aq) kg? 2 m $6; km a. pH=6.67 M -H b. H=10.67 , wcm c. pH=12.31 X ... &.§%Mg emit”: d. pH=10.03 ** @'gMg/W 3 e. pH=7.93 kt) :7 image” fix - @317?” :; t.fi2wa”q a”. 19W 2 3&9“? lat/+2- teams 17. 0.9.0571» 18. 93‘?” 9‘ 19. 9097‘?» 20. 0.04.0979: What is the pH of a 0.8 M anonymous acid, HA, solution that has a pKa = 5.67? HA(aq)+H20(l) H30+(aq)+A'(aq) ”184, 2 1531:, 3 W), @.%M ‘2“: X: 4.48 5.77 . ’21., .. 2 3'” in“ 2:. £1,184,328“) £8 ,3? 8 2... H112» 1.84878878 2.88 ** (955 8.23 75’1”: @4813 . .7 88.." conjugate base. mg; W8W .1... @k—CM 91 ms (pKa = 7.1) C13COOH (pKa = 0.7) CH3COOH(pKa = 4.7) N114+ (pKa=9.2) *** é...” H2803 (pKa =18) M‘s-«BM 1? léax Calculate the pH of a 10.0 M generic weak base BH3 solution. Kb = 3.8 X 10‘8. BH3 00 + H200) BH4+<aq> + OH'<aq) to ;< pH 2 10.79 ** ”I” pH = "8.24 “)6 ”a, W X pH= 3.21 W {92%.3‘38690 1,9 pH = 3.71 pH= 10.29 K 2. @131“ 2. {at 8880*”1 $828+: 3.113084“ 2 19 V781 Given the following reaction, which statement is true in the forward direction? time 1.13,) 5.18» (.12, 1304'3 (aq) + H20 (1) 4—; HPO4'2 (aq) + OH‘ (aq) P04.3 is the base and HPO4'2 is its conjugate acid. ** H20 is the acid and OH’ is its conjugate acid. 1304'3 is the acid and HPO4'2 is its conjugate base. H2O is the base and OH' is its conjugate acid. (a & d) are both correct. kw. 107W 8» Given the following acids and their associated pKa’s, which one would produce the strongest 21. (BONUS) A titration of 80 m1 of 0.4 M carbonic acid, H2CO3, required 40 m1 of 0.8 M NaOH to reach the equivalence point. What is the pH at this endpoint? Ka for H2C03 = 4.3 x 10’7 H2C03 (a9) + NaOH (aq) NaHCO3 (aq) \ Then, Fame fives: @ ELM"? y; )9 § 9 H = 3.953 . ‘7 p 39M 50.3.0 .. mafia a ma z. aw {0.3% b. pH = 4.104 <9ch H = 7.000 .. 7 p '2» ”5‘91 mwfi. W d- pH = 9.896 m 9- pH = 10.047 VT”; E‘LQW {Wile WW :: ...
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