exam 1 2008.doc

CHM 2045 Exam 1 (Form Code A) Fall 2008 Instructions: On your scantron sheet enter and bubble in your name, UF ID number (start on the leftmost space and leave any extra spaces blank), and Form Code (see above). You may retain your exam sheet (mark your answers on it and the scantron sheet) and any other sheets. Turn in only the scantron. 1. How many moles of oxygen are required to combust one mole of ammonia and produce dinitrogen tetroxide and water as sole products? (1) 0.57 mols (2) 1.75 mols (3) 3.5 mols (4) 4.0 mols (5) 7.0 mols 2. Given the thermochemical information: ?Hoformation (H2O (liq) ) = ? 285.8 kJ/mol ?Hoformation (C2H2 (gas)) = ? 26.7 kJ/mol ?Hoformation (CO2 (gas) ) = ? 393.5 kJ/mol The molar heat of combustion of acetylene, C2H2 (gas), is closest to? (1) ? 26.7 kJ/mol (2) ? 695.2 kJ/mol (3) ? 706.00 kJ/mol (4) ? 1046.1 kJ/mol (5) ? 1072.3 kJ/mol 3. If an aqueous NaOH solution is 14.6% by mass NaOH and has a density of 1.10 g/mL, the molarity, M, of this solution is closest to (1) 5.0 M (2) 4.0 M (3) 4.5 M (4) 3.5 M (5) 3.0 M 4. Which one of the following ions has the same number of electrons and neutrons? (1) 48 Ti 4+ (2) 35 Cl 1? (3) 14N 3? (4) 40 Ar 2+ (5) 80 Br 1? 5. In normal blood, there are about 5.4 x 109 red blood cells per milliliter. The volume of a red blood cell is about 90 x 10?12 cm3, and its density is 1.096 g/mL. How many liters of whole blood would be needed to collect 0.5 kg of red blood cells? (1) 1.0 L (2) 3.0 L (3) 0.9 L (4) 10.0 L (5) 9.0 L 6. The volume (in mL) of a 2.00 M CuSO4 stock solution that is needed to prepare 0.250 L of 0.400 M CuSO4 is closest to (1) 0.05 mL (2) 0.5 mL (3) 5.0 mL (4) 50.mL (5) 500. mL 7. The reaction between Al and Cl2 produces AlCl3. If 64.30 g Cl2 and 64.30 g Al are used, which reactant is in excess and how much of it will be left over after the reaction goes to completion? (1) Al, 16.31g (2) Al, 47.99g (3) Cl2, 47.99g (4) Cl2, 16.31 g (5) Al, 317.8 g 8. Silver has two naturally-occurring isotopes with masses of 106.905092 amu and 108.904756 amu. What are the percent abundances of each isotope, respectively? (1) 27.45 ; 72.55 (2) 50.25% ; 49.75% (3) 62.15% ; 37.85% (4) 15.84 ; 84.16 (5) 78.64 ; 21.36 9. A compound is found to contain the mass percentages: 34.4% Ni, 28.1% C, and 37.5% O. Determine the empirical formula of the compound. (1) NiCO (2) Ni2C2O2 (3) NiCO2 (4) Ni4CO4 (5) NiC4O4 10. A 127.5 g sample of Cr(NO3)3 ?xH2O is dried in an oven to drive off the H2O. When the resulting anhydrous salt is removed from the oven, its mass is 75.84 g. What is the value of x? (1) 1 (2) 3 (3) 5 (4) 7 (5) 9 11. Determine the heat of reaction for the oxidation of iron, 4 Fe(s) + 3 O2(g) ? 2 Fe2O3(s) given the thermochemical equations below. 2 Fe(s) + 6 H2O(l) ? 2 Fe(OH)3(s) + 3 H2(g) ?H = + 321.8 kJ 2 H2O(l) ? 2 H2(g) + O2(g) ?H = + 571.7 kJ Fe2O3(s) + 3 H2O(l) ? 2 Fe(OH)3(s) ?H = + 288.6 kJ (1) ? 1648.7 kJ (2) ? 1182.1 kJ (3) ? 505.3 kJ (4) + 360.5 kJ (5) + 1447.1 kJ 12. What is the net ionic equation for the reaction of aqueous sodium carbonate with aqueous iron(III) chloride to precipitate solid iron(III) carbonate? (1) Fe3+(aq) + CO32-(aq) ? Fe2CO3(s) (2) 3 Fe2+(aq) + 2 CO33-(aq) ? Fe3(CO3)2(s) (3) 3 Na2CO3(aq) + 2 FeCl3(aq) ? 6 NaCl(aq) + Fe2(CO3)3(aq) (4) 2 Fe3+(aq) + 3 CO32-(aq) ? Fe2(CO3)3(s) (5) Fe2+(aq) + CO32-(aq) ? FeCO3(s) 13. The label on a bottle of vinegar says that the contents are 4.50% by mass acetic acid (CH3COOH) and has a density of 1.00567 g / mL. How many moles are in 1.00 liter of the vinegar? (1) 0.754 mol (2) 1.33 mol (3) 2.70 mol (4) 16.7 mol (5) 27.0 mol 14. A mixture of butene, C4H8, and butane, C4H10, is combusted in air to give CO2 and water. Suppose you burn 2.86 g of the mixture and obtain 8.80 g of CO2 and 4.14 g of water. C4H8(g) + 6 O2(g) ( 4 CO2(g) + 4 H2O(g) 2 C4H10(g) + 13 O2(g) ( 8 CO2(g) + 10 H2O(g) What is the mass (in g) of butane in the mixture? (1) 0.635 g (2) 0.795 g (3) 1.27 g (4) 1.59 g (5) 1.91 g 15. What subshell is designated by the quantum numbers n=3, l=2? How many orbitals are in this subshell? (1) 3d; 15 orbitals (2) 3p; 3 orbitals (3) 3d; 5 orbitals (4) 3f; 7 orbitals (5) 3s; 1 orbital 16. What is the energy for a mole of photons of wavelength 242 nm? (1) 8.2x10-19 J/mol (2) 6.0x1023 J/mol (3) 4.9x105 J/mol (4) 9.7x10-17 J/mol (5) 4.9x10-4 J/mol 17. A radio broadcast has a frequency of 95 kilohertz.  What is the wavelength of this broadcast in km? (1) 3.2 x 10-3 km    (2) 3.2 km    (3) 32 km    (4) 320 km      (5) 0.032 km 18. What is the resulting molarity of Na+ ions in a solution prepared by mixing 200 mL of 0.04 M NaCl with 200 mL of 0.02 M Na2SO4? (1) 0.03 M (2) 0.04 M (3) 0.01 M (4) 0.02 M (5) 0.05 M 19. What is the percent yield if the reaction of 25.0 g of P4 with 91.5 g of Cl2 produces 104 g PCl3? (1) 93.7 % (2) 88.0 % (3) 24.0 % (4) 26.6 % (5) 107 % 20. A certain element "M" forms an oxide with the empirical formula M2O3. The oxide contains 68.45% of the element "M" by mass. What is the identity of the element "M"? (1) Cl (2) B (3) Cu (4) Fe (5) Cr 21. 100.0 mL of 1.020 M HCl and 50.0 mL of 2.040 M NaOH, each at 24.53ºC, are mixed in a Styrofoam cup calorimeter. What is the final temperature of the mixture if the heat of acid-base neutralization (?Hneut) = ?57 kJ per mole of H2O formed? (Assume density of the solution = 1.00 g/mL and specific heat of the solution = 4.184 J/g?ºC, and assume an insignificant heat capacity of the Styrofoam cup) (1) 15.3 ºC (2) 68.1 ºC (3) 27.8 ºC (4) 33.8 ºC (5) 43.1 ºC 22. For the hydrogen dichromate ion, HOCr2O6?, the oxidation number for Cr is (1) +2 (2) +4 (3) +6 (4) +8 (5) ?3 23. The aluminum foil in a package containing 150. ft2 of kitchen foil weighs 24.0 ounces. Aluminum has a density of 2.70 g / cm3. What is the approximate thickness of the aluminum foil in millimeters? (1 oz = 28.4 g, 12 in =1 ft, 1 cm = 10 mm, 1 in = 2.54 cm) (1) 0.00151 mm (2) 0.00181 mm (3) 0.0181 mm (4) 0.0151 mm (5) 0.001 mm 24. Which set of four quantum numbers below can be associated with an electron in a 4p orbital? (1) n = 4, l = 1, ml = 0, ms = +½ (2) n = 4, l = 1, ml = ?2, ms = +½ (3) n = 4, l = 0, ml = 1, ms = +½ (4) n = 4, l = 2, ml = 1, ms = +½ (5) n = 4, l = 1, ml = 2, ms = +½ 25. What is the energy of a photon absorbed during an electronic transition from the n = 2 to the n = 5 states in the hydrogen atom? (RH = 2.18 x 10-18 J) (1) 6.54 x 10-19 J (2) 4.58 x 10-17 J (3) 6.54 x 10-17 J (4) 4.58 x 10-19 J (5) 6.63 x 10-34 J PAGE PAGE 2