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Unformatted text preview: Practice Flnal 2007: FILL IN YOUR STUDENT ID NUMBER, NAME. AND TEST FORM=A
FOR NUMERICAL QUESTIONS CHOOSE THE CLOSEST VALUE (R = 8.314JIK-rnol= 0.08206 L-atmlmol-K)
1. When 1.67 mL of 3.0M weak acid Ex is reacted with 5.0 mL of 3.34 M NaOl-l, the temperature increases by 0515 °C. Calculate the molar heat ofneu ' tion. (assume 4.18 Jig-0C and 1.00g/mL)
(a) -57,0001; (b) 2,800 J; (c) 2,800 1;. (d) 7,000 J; 931100001 2. Predict that the order of heats of vaporization of the following three substances is:
a CH3CHOHCH3 > CH3CH2CHO> Al; (b) CH3CH01-1CH3 > Al> CHJCH2CHO; '
Al > CHJCHOHCH3 > CH3CH2CHO; (d) Al> CH3C1-12CH0 > CH3CHOHCH3;
e CH3CH2CHO > CH3CH0HCH3 > Al \/ 3. Which has the largest lattice energy. (n.0,; (b) 1.120,; (c)NaF; (d) crucuzcnzou; (e) sto. 4 Calculate the standard reaction enthal y for the followin reaction in kJ/mol
/ P g
NzHaO) + His) -> 2NH3(E) Given: 1/2N2H4(l) +l/2 02(g) —> 1/2N2(g) + H20(g) AH° = —27l.5 ld-mor'
H2(g) + 1/202(g) —> Hzolg) AH° = -242 kJ-mol" 2N;(g) + 5H2( 4NH:(g) ° = 484.4 kJ-mol'I
(a) ~935; (b) -l 1 19; @7151; (d) -59; (e) -243 5. Calculate the standard enthalpy of formation of blcyco[l.l.0]butanc (shown below) in kJ/Mol
H given the standard enthalpies of formation of C(g) and H(g), 717 and 2| 8 kJ-mol",
Cal" 5 respectively, and the average C-H and C-C bon thalpies, 412 and 348 kJ-mol",
respectively. (a) 175; (b) -472; (c) 312; ”(d) $36; (e) -l24 K c
H 6. Consider the following processes. (Treat all gases as ideal.)
I. The pressure of one mole of oxygen gas is allowed to double isothermally. ‘7 1’ S I;
2. Carbon dioxide is allowed to expand isotherrnally to 10 times its original volume. \j ‘t 5.43
3. The temperature of one mole of helium is increased 25°C at constant pressure. -( 4‘. Q
4. Nitrogen gas is compressed isothermally to one half its original volume. V \ 5
5. A glass of water loses 100 J of energy reversibly at 30°C. easy by v 9 <5
Which of these processes leads to an ' rease in entropy? s A,
(a) 1 and 4; (his; Wand 5; 2 and 3; (e)1and2 \/ 7. Which of the following statements is most accurate: (a) the only way to increase the entropy of a substance is to
increase the temperature; (b) the entropy of a substance increascs more going from solid to iquid than from liquid
to solid; (c) heavy gasses have greater entropy than light gasses because they move slower at a given temperature; / eavy gasses have greater entropy than light gasses because their energy levels are more closely spaced;
e reactions which in the forward direction cause a net increase in moles of gas are always spontaneous because
they have a positive entropy change. 8. Which of the following statements is true? (a) The molar entropy does not depend on the tructure of the
compound; /(bTThe molar entro y of 1420(1) is about the same as the molar entropy of i All isothermal
process that leads to a decrease in e energy is spontaneous; (d) If AG,° > 0, then the reaction is spontaneous;
(e) All processes that give positive changes in energy are spontaneous. 9. Calculate AG,° for the decomposition of mercury(li) oxide at 298 K in kJ/mol. Estimate any missing data.
2Hg0(s) —> 2Hg(l) + 02(g)
AH¢°, kJ-mol" —90.83
5.3, J-K‘kmol" 70.29 76.02 205.14
(a) -l 17; (la/246; . 65; .117; (e) -246
10. The triple point of iodine is at 0.12 atrn and I 15°C. This means the (a) liquid 12 is more dense than 12(s)' iquid I; cannot exit above 1 15°C;/(c)’lz is liquid at room temperature; d the only stable phases are gas an solid
below 90 torr; (e) the only stable phases are gas and liquid below 5°C / l 1. Rank the following compounds according to increasing solubility in water.
1. CH3—CH2-CHz—CH3; II. CHrCHz—O-CHrCﬂg; 111. C (CH2)3-NH3; IV. CHy—OH '
(A) I < 111 < IV< II; (b) I < II < IV< III; (e) Ill< IV< ll < I; . d) l < H <lll<1V; (e) No order is correct. \ 12. Which aqueous soluti will have the lowest vapor pressure at 100°C assuming the solutions are ideal?
(a) 0.03 M sucrose' (b) .02 M NaCl; (c) 0.01 M CaF;; ((1) pure H20;
(e) there is a tie fo st vapor pressure l3. 14. 15. 16 17. 23.
24. 25. 26. 27 28. 29. 30. When Cue/1804), is dissolved in water, solution becomes hotter. This information indicates that if the
t erature of the solution is raised, / AH will become positive; AH will become zero;
ﬁe solubility of Ce2(SO4)3 will decrease; (d) the solubility of ez(SO4), will increase; 6 solubility of Ce2(804)3 will not change. For the following reaction: 2N0;(g) <-> 02(g) + 2N0(g) Starting with on] P” (NOI) = 0.500, at equilibrium
.152; (b) 0.174; (c) 0.200; (d) 0.326; (e cannot be calcu ated because K, is not given motel pressure was 0.674 atm. Calculate the e uilibrium partial ressure o N0;(g) in atm.
La jNHﬁg) + 302(g) <-—> 2Nz(g) + 61-120(g), K = 10“0 at a certain temperature. Initially, all reactants and products
have concentrations equal to 12 M. Estim he concentration of N; at equilibrium.
(a) 6M; (b) 0M; (c) 3M; (d) 12M; ‘ e) M Consider the following reaction: Br2(l) <->23r(g). What conditions favor th uction of bromine liquid,
Br(l),? (a) high T and low P; (b) high T and high P; (c) low T and low P; (d ow T and high P;
(e) low T and a small container volume. 1 Which of the following is true?,(a)’When the value of Q is large, the equilibrium lies on the product side of the
equilibrium reaction; _ (b) When the value of K is large, the equilibrium lies on the reactant side of the
equilibrium reaction; (c) A small value of K means that the .-»- 'librium concentrations of the reactants are small
compared to the equilibrium concentrations of the products; ’1 A large value of K means that the equilibri
concentrations of products are large compared to the equilibri 0- concentrations of the reactants; - en the value of K is small, the equilibrium lies on the product side of the equilibrium reaction. Which of the following cannotexit simultaneous in high concentration (>0.l M) in so ,‘on?
(a) EJCAJ and HE]; (bull-J14? and KC]; (c) Mr and l-lCN; (d) Nl-LBr and ; e 1101 and KP
g . . .. VAN). Wkﬂwesawrs
@Sh 0.0666M solunon Will be the most ba31c? (think about re t1ve conjugate acid strengths). aCHJCOO; (b) K(CH1C1)COO; (C) Na(CHCl2)COO; KBI’; (e) NH4C1;
The conjugate acid of H2P04' is (a) H302 (b) P04"; (c) HPOf'; (d) H; 043/.1390, A 0.666 M solution of a triprotic acid 11%, is 0.75% ionized to -. Calculate 1- Assume Kn is 0.001% of K..
and Ka, = 0.001% 1c, (a)1.5; (b) 3.0; (c) 7.6 x 10"; (d) .8 x 10"; e) .s x 10'5 Calculate the pH of the solution resulting’from the addition of 10.0 mL M HCl to 50.0 mL of 0.12 M NaCN solution? (K, = 6.2 x 10' for HCN). (a) 4.1; (b) 5.5; .5; (d) 9.2; (e)9.9 What is the pH at the equivalence point fo_ : - 'tration of the equivalence point for the titration of 0.26 M CH3N1~11
with 0.26 M Hc10. (aq)? (pr = 3.44). w 2; (b) 2.16; (c) 2.01; (d) 5.57; . (e) 7.00 Which of the following will be a buffer solution? (a) 0.066 moles N'aSH + 100 mL of 0.66M N113;
(b) 100 mL of0.lM NH, +100 mL of 0.1M HF; (c) 10 of0.l M NH, + 200 mL of0.1 M HCl;
(d) 50 m1. of 0.1 M KCl-I3C00 +100 mL of 0.1 M NI-l4Cl, @066 moles NaOH «1» 200 mL of 0.5 M Nl-LCl How many grams of NaOH (MW = 40ymo required to make a pH = 9.66 buﬁ‘er ﬁ'om 0.666 L of 0.666 M HCN
(pKa = 9.31) (a) 0.3; (b) 1.0; (c) 2.2; 12; (e) 40 Calculate the molar solubility of Ba3(P04)2 in a 0.2 M BaClz solution. (Ksp = 1.3 x 10'”).
(a) 1.7 x 10*; (b) 3.4 x 10‘; (c) 1.7 x 10"“; (d) .4 x 10'”; (e) 3.4 x 10"“; At 25 ‘3c the K... for MgcoJ is 4.0 x 10" and that for BaCO; is 8.1x 10'9. Assuming that both Mg‘2 and Bar2 imrs
have 0.00100 M concentrations, what is the equilibrium concentration of carbonate ions that will precipitate the
maximum conce tion of Ba2+ without precipitating any Mg“z at 25 °C. (a) 3.5 x 10"; (b) 4.2 x 10"; (c) 3.2 x Mayﬂo x 104; N8 x 10"; For metal sulﬁde, which of the following might increase the solubility? READ ALL THE ANSWERS AND PICK
THE BEST ONE (a) adding a strong acid; (b) adding strong base if the me hydroxide is insoluble, (c) adding
ammonia if the metal forms a complex ion with ammonia, (d) two of thes 33) 1 three of these. What is the concentration of free Fe” in a solution that is 1.00 M in [Fe(CN)6]" and 10.0 M in CN‘.
Kf= 7.7 x10“ for Fe2++ 6CN' <--> [Fe(JCN) “
(a) 1 x 10'”; ,(b)1x10'”; (c) 8 x 10' f- d 310'“; (e) 8 x10"; A solution is made by mixing 500 mL of 4.0 M NH; and 500 mL of 0.40 M AgN03. Calculate the concentration of the Ag‘ ion remaining in solution; = 1.72 x 107 for Ag‘(aq) + 2NH3(aq) <—> Ag('NH3)z+
(a) 2.0 M; (b) 12 x 10"M; (c) x 10'9 M; (d) 1.6 M; (e) 0.20 M Final: FILL IN YOUR STUDENT ID NUMBER, NAME, AND TEST FORM=A ...
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- Winter '10