Form Code A CHEM 1025 Final Exam 28 Apr. 2010 Instructions: On

Form Code A CHEM 1025 Final Exam 28 Apr. 2010 Instructions: On your scantron sheet enter your name, UF ID number, and Form Code (start with the first space and leave the last space blank). This exam consists of 25 multiple choice questions each worth 8.0 points for a total maximum of 200 pts. Keep your exam sheet (mark your answers on it and on the scantron sheet). Turn in only the scantron. Any bubbling error will count as an incorrect response, including wrong form code and answers. Potentially Useful Information: 1 inch = 2.54 cm; 12 inches = 1 foot; 1 mile = 5280 ft 1. Compound X has three isotopes: X-28, X-29, and X-30. X-28 has a mass of 27.9769 amu and is 68.3% abundant. X29 has a mass of 28.9765 amu and is 19.2% abundant. X-30 has a mass of 29.9737 amu is 12.5% abundant. Calculate the atomic mass of compound X. (1) 28.4184 amu (2) 28.4 amu (3) 28.4184232 amu (4) 28.42 amu (5) 28.418 amu 2. Name the following compounds: CrCl4, Fe(NO3)2, N2O2. (1) Chromium (II) chloride, iron (II) nitrite, dinitrogen dioxide (2) Chromium (II) quatrachloride, iron nitrate, nitrogen (II) oxide (3) Chromium (IV) chloride, iron (II) nitrate, dinitrogen dioxide (4) Chromium tetrachloride, iron (II) nitride, nitrogen (II) dioxide (5) Chromium (IV) chlorine, iron nitrite, nitrogen dioxide 3. How many atoms of phosphorous are there in 2.0 g of P4S10. (2) 2.5 x 1024 (3) 4.3 x 1022 (1) 1.9 x 1025

(4) 1.1 x 1023

(5) 1.1 x 1022

(4) 12.1

(5) 13

4. Perform the following calculation to the correct number of significant figure. [(2.3 x 106) ÷ (9.63 x 105)] + 9.76 (1) 13.8

(2) 12.15

(3) 14

5. A pure titanium cube has an edge length of 0.973 ft. How many titanium atoms does it contain? (DTi = 4.50 g/cm3). (1) 1.22 x 1024 atoms (2) 2.00 x 1025 atoms (3) 1.48 x 1027 atoms 22 (4) 5.21x 10 atoms (5) Insufficient information 6. What volume (in mL) of 0.500 M NaOH is required to titrate 150.00 mL of 1.10 M H2SO4 to the equivalence point? (1) 660. mL 7.

(2) 12.5 mL

(3) 25.0 mL

(4) 330. mL

(5) 1320 mL

Name of the compound (NH4)2CrO4 (1) Ammonia chromate oxide (2) Ammonium chromate (3) Ammonium dichromate (4) Ammonia chromate (5) Ammonia dichromate

8.

What is the complete ionic equation for the following balanced reaction: NH4Cl(aq) + NaOH(aq) → H2O(l) + NH3(g) + NaCl(aq) (1) H+(aq) + OH-(aq) → H2O(l) (2) NH4+(aq) + OH-(aq) → H2O(l) + NH3(g) (3) NH4+(aq) + Cl-(aq) + Na+(aq) + OH-(aq) → H2O(l) + NH3(g) + Na+(aq) + Cl-(aq) (4) No Reaction (5) NH4+(aq) + Cl-(aq) + Na+(aq) + OH-(aq) → Na+(aq) + Cl-(aq)

9.

The following reaction is used to obtain iron from iron ore: Fe2O3(s) + 3CO(g) → 2Fe(s) + 3CO2(g) The reaction of 92.134 g Fe2O3 with 143.21 g CO produces 2.45 g Fe. Determine the percent yield. (1) 3.80%

(2) 7.60%

(3) 1.29%

(4) 4.21%

(5) 63.4%

10. Calculate the molecular formula for nicotine based on its elemental mass percent composition (C 51.28%, H 9.40%, O 27.35%, and N 11.97%) and its molar mass (~234 g/mol). (1) C10H14N2

(2) C5H11O2N

(3) C8H16O4N4

(4) C10H22O4N2

(5) C12H16O2N3

11. If a system emits 200 kJ of energy during a process, what is the change in energy for the surroundings (∆Esurr)? Is this process endo- or exothermic for the system? (1) +200 kJ; endothermic (4) -200 kJ; exothermic

(2) +200 kJ; exothermic (5) Not enough information

(3) -200 kJ; endothermic

12. Use Hess’ Law and the following data to determine the value of ΔHrxn for the following reaction: 5 C(s) + 6 H2(g)  C5H12(l) C5H12(l) + 8 O2(g)  5 CO2(g) + 6 H2O(g) C(s) + O2(g)  CO2(g) 2 H2(g) + O2(g)  2 H2O(g) (1) 4382.8 kJ

(2) 87.8 kJ

(3) -4382.8 kJ

ΔH1 = -3505.8 kJ ΔH2 = -393.5 kJ ΔH3 = -483.5 kJ (4) -2628.8 kJ

(5) -2988.8 kJ

13. A system absorbs 462 kJ of heat and the surroundings do 593 kJ of work on the system. What is the change in internal energy of the system? (1) 131 kJ

(2) -1055 kJ

(3) -131 kJ

(4) 1055 kJ

(5) Not enough information

14. The explosive nitroglycerin (C3H5N3O9) decomposes rapidly upon ignition according to the following equation: 4 C3H5N3O9(l) → 12 CO2(g) + 10 H2O(g) + 6 N2(g) + O2(g) ∆Hrxn = -6132 kJ Calculate the standard enthalpy of formation (∆Hf) for nitroglycerin. For CO2(g), ∆Hrxn = -393.5 kJ/mol. For H2O(g), ∆Hrxn = -241.82 kJ/mol. (1) -1008 kJ/mol

(2) -1714 kJ/mol

(3) 4791 kJ/mol

(4) -114 kJ/mol

(5) 1008 kJ/mol

15. In a coffee-cup calorimeter, 3.19 g of NH4NO3 is dissolved in enough water to make 35.0 mL of solution. The initial temperature is 27.3 oC and the final temperature is 22.6 oC. Calculate the change in enthalpy for the reaction in kJ/mol. (Assuming 1.0 g/mL as the density of the solution). (1) -63 kJ/mol

(2) 17.1 kJ/mol

(3) -688 kJ/mol

(4) -17.1 kJ/mol

(5) 688 kJ/mol

16. Determine the bond energy of a Cl-Cl bond given the following information. H3C-H(g) + Cl-Cl(g) → H3C-Cl(g) + H-Cl(g) ∆Hrxno = -113 kJ Bond Bond Energy (kJ/mol) H-Cl 431 C-Cl 339 H-C 414 (1) 395 kJ/mol

(2) -170 kJ/mol

(3) 205 kJ/mol

(4) -431 kJ/mol

(5) 243 kJ/mol

17. Determine whether a bond between each of the following pairs of atoms would be pure covalent, polar covalent, or ionic: B and O Sr and O Ni and Ni As and Br Cs and Cl (1) Pure, Ionic, Pure, Ionic, Ionic (4) Polar, Polar, Ionic, Pure, Ionic

(2) Polar, Polar, Pure, Ionic, Ionic (5) Pure, Ionic, Pure, Polar, Polar

(3) Polar, Ionic, Pure, Polar, Ionic

18. What is the formal charge of the central atom in the hydronium ion [H3O]+ ? (1) -2 (2) -1 (3) 0 (4) +1 (5) +2 19. How many resonance structures are possible for nitric acid, HNO3? (1) 0 (2) 1 (3) 2

(4) 3

(5) 4

20. Use the Born-Haber cycle and the following reactions to calculate the electron affinity of chlorine. ∆Hfo = -411 kJ/mol Na(s) + ½ Cl2(g) → NaCl(s) Na(g) → Na(s) ∆Hfo = -108 kJ/mol ½ Cl2(g) → Cl(g) ∆Hfo = +122 kJ/mol + Na (g) + e → Na(g) ∆Hfo = -496 kJ/mol + Na (g) + Cl (g) → NaCl(s) ∆Hfo = -788 kJ/mol (1) -349 kJ/mol

(2) -1103 kJ/mol

(3) 859 kJ/mol

(4) -1681 kJ/mol

(5) -859 kJ/mol

21. What are the electron geometry and the molecular geometry of ClF3? 1) Trigonal planar, Trigonal Planar 2) Tetrahedral, Trigonal Planar 3) Tetrahedral, Trigonal Pyramidal 4) Trigonal Bipyramidal, T-Shaped 5) Octahedral, Square Pyramid 22. Determine whether the following molecules or ion is polar (p) or nonpolar (np): NH4+, H2O, XeF2, CH3CH3 1) np, np, np, np 2) p, p, p, np 3) p, p, np, np 4) p, np, np, np 5) np, p, np, np 23. Predict the molecular shape and give the approximate bond angles of the SBr2 molecule. (A) Linear, 180° (B) Bent, 109.5 (C) Tetrahedral, 109.5° (D) Trigonal pyramidal, 109.5° (E) Trigonal planar, 120° 24. Which of the following liquids are likely to be soluble with water: methanol (CH3OH), pentanol (C5H11OH), hexane (C6H14), and acetic acid (CH3CO2H)? (A) Methanol and pentanol (B) Methanol and acetic acid (C) Methanol and hexane (D) Hexane and pentanol (E) Acetic acid and hexane 25. Which of the following substances will exhibit dipole-dipole intermolecular forces? (A) C2H4

(B) SO2

(C) CO2

(D) F2

(E) Ar