CHEM 112 Practice Exams (Various)

CHEM 112 Practice Exams (Various) - CHEM 112 EXAM 1 FALL...

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----- CHEM 112 EXAM 1 FALL 2008 NAME: Dr Thomas Berg Total Points - 150 Questions 1-30: 5 points each USEFUL INFORMATION: No = 6.022 x 10 23 mor l R = 8.314 J . l K- I 8E=q+w
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1. What is the molar solubility ofCdS when the salt is dissolved in sodium sulfide solution that has a concentration ofS 2 -ion of3.0 x 10- 3 M Assumed reaction: CdS(s) --+- Cd 2 +(aq) + S2-(aq) Ksp = 3.6 X 10- 29 a) 6.0 x 10- 15 M b) 1.2 X 26 M c) 3.4 X M d) 1.2 X M e) 8.3 x 10- M 2. Consider the following information: .6.W = -311 kJ BE for C-C = 350. kJ / mol H-H = 435 kJ / BE for C-H = 410. kJ / mol What is the estimated value for the bond dissociation energy for the carbon to carbon triple bond? a) 1050. kJ / mol b) 833 k1 / mol c) 807 k1 / mol d) 397 k1 / mol e) 884 kJ / mol 3. A saturated solution of Ag2Cr04 formed by dissolving A~Cr04 in water has a Ag + ion concentration of 1.6 x 10-4 M. What is the Ksp for Ag 2 Cr0 4? a) 2.0 x 10- 12 b) 2.6 X 8 c) 4.1 X 12 d) 5.1 X 8 e) 1.6 x 10- 11
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4. Consider the following data: ilHo (kJ / mol) Cf 2 (g) -- 2 c.e(g) 242.3 h(g) -- 2 leg) 151.0 ICt(g) -- leg) + ct(g) 211.3 h(s) -- h(g) 62.8 What is the standard heat of formation ofthe compound ICt(g) a) 14.7 kJ / mol b) 16.8 mol c) 72.6 mol d) -14.7 kJ / mol e) None ofthese is correct. 5. All of the following are state function except: a) enthalpy b) internal energy. c) heat. d) temperature. e) pressure. 6. Which is the ~ soluble salt ofthe following set at identical temperatures? a) Ba(OH)z with Ksp = 5.0 X lO-3 b) Ca(OH)z with Ksp = 4.7 X 10-0 c) Cr(OH)3 with Ksp = 6.7 X 10- 31 d) Cd(OH)z with Ksp = 5.3 X lO-IS e) Fe(OH)z with = 2.5 X 37
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7. The heat of vaporization ofwater at 373 K is 40.7 kJ / mol. When 9.00 g ofsteam condense at 373 K, the value for the change in enthalpy (~H) is: a) -8.14 x 10 1 kJ b) 2.04 X 10 1 c) 8.14x 10 1 d) -2.04 x 10 1 e) None ofthese is correct. 8. A solution which is 0.65 M is each ofPb 2 +, Ag+, and Hgl+ has the CC- concentration adjusted to 1.0 x 10- 9 M. Which ofthe following chlorides will precipitate? Ksp for PbCt2 = 1.6 x 10- 5 Ksp for Hg 2 Ct 2 = 4.3 X 10- 19 Ksp for AgCt = 1.7 x 10- 10 a) PbCt2 only b) AgCt only 9. A saturated solution Ag2 C0 3 was fonned by dissolving Ag 2 3 in water. lfthe Ksp ofAg 2 3 is 8.2 X 12 , what is the concentration ofthe silver ion? a) 2.6 x 10- 4 M b) 1.6 X 8 M c) 1.3 X 10-4 M d) 3.2 X 4 M e) 1.6 x 10-4 M
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10. As a purity check for industrial diamonds, a 10.25 carat (carat 0.2000 g) diamond is heated to 74.21 °C and immersed in 26.05 g of water (specific heat capacity of water = 4.184 Jig' K) in a constant pressure calorimeter. The initial temperature ofthe water is 27.20 dc. What is the final temperature of the water and diamond (specific heat capacity ofdiamond is 0.519 J / g . K? (Assume no heat is lost to the surroundings.) a) 27.65°C b) 23.51 °C c) 28.85°C d) 28.18 DC e) None ofthese is correct. 11. A solution is 0.050 M in K 2 S0 4 and 0.050 M K 2 CrO. .. A solution ofPb(N03)2 is added slowly without changing the volume appreciably. The Ksp value for PbS0 4 is 1.8 X 10- 8 and the Ksp value for PbCr04 is 1.8 x 10- 14 . What is the concentration of CrOl- when 4 just begins to precipitate? a) 1.3 x 10- 4 M b) 5.0 X 10.
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CHEM 112 Practice Exams (Various) - CHEM 112 EXAM 1 FALL...

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