chem finals -MCFinalPractice

chem finals -MCFinalPractice - Chemistry 142D PRACTICE...

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Chemistry 142D P RACTICE F INAL E XAM All problems are worth 10 points for a total of 200 points on the exam. 1. A paper cup has a mass of 1.00 kg when it is filled with 73.59 mL of mercury (density Hg = 13.546 g/mL). What is the mass of the empty cup? a) 31 g b) 31.5 g c) 31.50 g d) 0 × 10 1 g e) 3 × 10 1 g 2. Which are alkaline earth halides? a) CaF 2 , MgBr 2 , SrI 2 b) NaI, KBr, LiF c) PbI 2 , PbBr 2 , CdF 2 d) MgO, MgS, CaO e) Al 2 O 3 , In 2 O 3 , Ga 2 S 3 3. Boron naturally occurs in two isotopic forms. The more common isotope is 11 B (atomic mass 11.01 amu), which is 80.00% abundant. The average atomic mass of boron is 10.81. What is the mass of the other isotope? a) 11.00 amu. b) 10.91 amu. c) 10.01 amu. d) 11.01 amu. e) 10.81 amu. 4. In the reaction Cu (s) + AgNO 3 (aq) Cu(NO 3 ) 2 (aq) + Ag (s), identify the oxidizing agent. a) Cu(NO 3 ) 2 b) Ag c) Cu d) AgNO 3 e) none of these 5. What are the oxidation numbers of carbon in CO 2 and CO 3 2- , respectively? a) +4, +4 b) +2, +6 c) +4, +6 d) -4, -4 e) -4, -6
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Chem 142D Practice Final 2009 December 14 Page 2 6. Pyrite (FeS 2 ), an impurity in some coals, reacts with oxygen to form the air pollutant sulfur dioxide. When 2.0 × 10 4 kg of coal containing 0.050 mass percent pyrite is burned, what mass of sulfur dioxide will form? FeS 2 (s) + O 2 (g) SO 2 (g) + FeO(s) (Caution: unbalanced equation!!) a) 2.1 × 10 7 g b) 1.1 × 10 6 g c) 1.l × l0 4 g d) 11 g e) none of the above 7. Oxygen gas, generated by the reaction 2KClO 3 (s) 2KCl(s) + 3O 2 (g), is collected over water at 27 ° C in a 2.00-L vessel at a total pressure of 760. torr. (The vapor pressure of H 2 O at 27 ° C is 26.0 torr.) How many moles of KClO 3 were consumed in the reaction? a) 0.0527 moles b) 0.0790 moles c) 0.0813 moles d) 0.119 moles e) none of these 8. At –80 ° C, K C for the reaction N 2 O 4 (g) 2NO 2 (g) is 4.66 × 10 –8 . We introduce 0.050 mole of N 2 O 4 into a 1.0-L vessel at –80 ° C and let equilibrium be established. The total pressure in the system at equilibrium will be: a) 0.23 atm b) 0.79 atm c) 1.3 atm d) 2.3 atm e) none of these 9. An unknown liquid is vaporized in a 273-mL flask by immersion in a water bath at 99 ° C. The barometric pressure is 753 torr. If the mass of the liquid retained in the flask is 1.362 g, what is its molar mass? a) 20.4 g/mol b) 40.9 g/mol c) 154 g/mol d) 184 g/mol e) none of the above
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Chem 142D Practice Final 2009 December 14 Page 3 10. Which of the following is the correct order for increasing pHs for 0.10 M solutions of HNO 3 , KCl, NH 4 Cl, KOH, and NaC 2 H 3 O 2 ? (K a for HC 2 H 3 O 2 is 1.80 × 10 –5 , K a for NH 4 + is 5.56 × 10 –10 ). a) KCl, NH 4 Cl, HNO 3 , KOH, NaC 2 H 3 O 2 b) HNO 3 , KCl, NH 4 Cl, KOH, NaC 2 H 3 O 2 c) NH 4 Cl, HNO 3 , KCl, KOH, NaC 2 H 3 O 2 d) HNO 3 , NH 4 Cl, KCl, NaC 2 H 3 O 2 , KOH e) none of these 11. In pure liquid ammonia, the equilibrium concentrations of both NH and NH are 3 × 10 4 + 2 –14 M at –45 ˚C. Which of the following equations always holds for liquid
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chem finals -MCFinalPractice - Chemistry 142D PRACTICE...

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