INSTRUCTIONS: (1) Write your name in the blank titled "NAME" on the scantron form provided.

Transcription

1 INSTRUCTIONS: (1) Write your name in the blank titled "NAME" on the scantron form provided. (2) Write your section number in the blank titled "SUBJECT" on the scantron form. (3) Write your Student ID number in the blanks titled "ID NUMBER" on the scantron form. Use 1 in place of the A in your ID number. (4) Fill in BOX XX in the "TEST FORM" box on the scantron form. (5) Put your name HERE: (6) Perform all your scratch work on this test and hand in with the scantron form at the end of the exam. You are allowed to use a calculator and one 5x7 index card of notes (both sides) H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn Fr Ra Ac Lanthanides Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Actinides Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr Some useful constants and relationships: Specific heat capacities (in J/g. K): H 2 O (l) = 4.184; Al (s) = 0.900; Cu (s) = 0.387; Steel (s) = J = 1 L. atm 1 atm = 760 Torr 1J = 1kg. m 2 /s 2 1 ev = x J R = Ideal gas constant: L. atm. mol -1. K -1 = J. mol -1. K -1 Avogadro constant: x mole -1 Planck's constant = h = x J. s c = speed of light: 3.00 x 10 8 m/s R H = x 10-2 nm -1 C 2 = second radiation constant = 1.44 x 10-2 K. m Tλ max = 1 5 C Emitted power (W) 2 = (constant)t 4 Surface area (m 2 ) e = mc 2 c = λν 1 λ = R 1 H 2 n 1 2 E = hν E = hc E(in Joules) = Z 2 1 n 2 λ n 2 1

2 1. Iridium exists in two isotopes, 191 Ir (atomic mass amu) and 193 Ir (atomic mass amu). If the average atomic mass of Ir is amu, what is the percent abundance of 191 Ir? a) 39.47% b) 37.40% c) 47.84% d) not enough information is given ANSWER: B 37.40% 2. Which of the following reactions is the least endothermic? a) Si (g) Si + (g) + e - b) P (g) P + (g) + e - c) S (g) S + (g) + e - d) Cl (g) Cl + (g) + e - e) Ar (g) Ar + (g) + e - 3. Consider the reaction: Identify the reducing agent in this reaction. a) NO b) O 2 and NO 2 c) O 2 d) NO 2 2NO (g) + O 2(g) 2NO 2(g) 4. Consider the reaction of chlorine atoms responsible for depleting ozone in the stratosphere: Cl (g) + O 3(g) ClO (g) + O 2(g) If 5 moles of O 3 are consumed in this reaction, how many moles of O 2 are produced? a) 5 b) 7.5 c) 2 d) 3 2

3 5. Which of the following compounds has the most covalent bond character? a) HF b) HBr c) HCl d) HI e) KF 6. Which of the following compounds are paramagnetic (check all that apply)? a) NO 2 b) O 3 c) NO d) N 2 e) CF 2 Cl 2 and C are paramagnetic 7. What is the value of the F-P-F bond angle (θ) in PF 3? a) 120 < θ < 180 b) < θ < 120 c) 90 < θ < d) 60 < θ < 90 e) θ = 120 (actual value is 96.3 ) 8. What is the oxidation number of bromine in BrF 5? a) -1 b) +4 c) +5 d) A coin of mass g is dropped into a graduated cylinder containing ml of water. The volume of the water level rises to ml. What is the density of the coin? a) g/ml b) g/ml c) g/ml d) g/ml 3

4 10. The transition of an electron from the principle quantum number n = 4 to n = 2 in atomic hydrogen causes emission of a photon of what wavelength? a) 1117 nm b) 1094 nm c) 365 nm d) 486 nm 11. The molecular formula for a compound is C 12 H 16 N 4 O 8, and its molar mass is g/mol. What is the molar mass of the empirical formula of this compound? a) g/mol b) g/mol c) g/mol d) g/mol ANSWER: E it is for C 3 H 4 NO How many unpaired electrons are there in a ground state atom of Fe (g)? a) 0 b) 8 c) 4 d) How many unpaired electrons are there in a ground state ion of Fe 3+ (g)? a) 0 b) 8 c) 4 d) A sample of Li 2 molecules contains only two isotopes of lithium, 5 Li and 7 Li. At what amu values will the peaks in the mass spectrum of this sample occur? a) 5 and 7 amu b) 5, 6, and 7 amu c) 10, 12, and 14 amu d) 10, 11, 12, 13, and 14 amu e) 12, 13, and 14 amu 4

5 15. What volume of an aqueous solution M in KMnO 4 contains mol of potassium ions? a) 26 ml b) 325 ml c) 38 ml d) ml 16. For the following Lewis structure, considering the atoms from left to right, the formal charges on N, C, and O, respectively, are a) +5, +4, +6 b) -5, -4, -6 c) +1, 0, -2 d) 0, 0, What is the bond order of the N-O bonds in the nitrate ion (NO 3 - )? a) 1 or 2 b) 120 c) d) resonance 18. What is the balanced net ionic equation for the reaction that occurs when aqueous copper (II) chloride is added to aqueous lithium sulfide? a) CoCl 2(aq) + Li 2 S aq) Co 2+ (aq) + 2Li + (aq) + 2Cl - (aq) + S 2- (aq) b) Cu + (aq) + S 2- (aq) Cu 2 S (s) c) Co 2+ (aq) + S 2- (aq) CoS (s) d) Co + (aq) + S 2- (aq) Co 2 S (s) ANSWER: E (it is Cu 2+ (aq) + S 2- (aq) CuS (s) ) 5

6 19. What is the electron configuration of the (gas phase) Fe 2+ ion? a) [Ar] 4s 2 3d 4 b) [Ar] 4s 2 3d 6 c) [Ar] 4s 2 3d 8 d) [Ar] 3d 6 e) [Ar] 4s 2 3d 10 4p The set of quantum numbers n = 4, l = 1, m l = 0 and m s =+1/2 describes an electron in which orbital? a) 4f b) 4d c) 4p d) 4s 21. Which of the following gas phase atoms or ions is paramagnetic (check all that apply)? a) H b) He c) V 2+ d) O e) Mg, C, and D 22. Which of the following has 5 protons, 3 neutrons, and 5 electrons? a) 5 B 2- b) 7 B c) 10 B d) 8 B 2- ANSWER: E (it is 8 B) 23. When the following reaction is balanced, 5 moles of KClO 3 reacting with excess C will produce how many moles of CO 2? 2KClO 3 + 3C 3CO 2 + 2KCl a) 3 b) 3.33 c) 5 d) 7.5 6

7 g of NaClO 4 is diluted to the mark with water in a ml volumetric flask. What is the concentration, in molarity, of the solution? a) 1.36 x 10-2 M b) M c) 4.07 M d) M ANSWER: E it is 1.36 M 25. The number of grams of F in 50.0 g of NaBF 4 is a) 34.6 g b) 8.65 g c) g d) 69.2 g 26. Which of the following is the most plausible structure for the PCl 4 + ion: a) b) c) d) e) 27. Which is the most plausible geometry for the XeF 4 molecule (electron lone pairs are not shown)? a) b) c) d) e) ANSWER: B 7

8 28. Which is the most plausible Lewis structure for thiocyanate? The Pauling electronegativities of S, C, and N are 2.5, 2.5, and 3.0, respectively a) b) c) d) e) 29. Aspirin contains only C, H, and O. Combustion analysis of a 4.00 g sample produces g of water and g of CO 2. What is the empirical formula of this compound? a) C 9 H 8 O 4 b) C 3 H 2 O c) C 6 H 3 Cl 2 d) C 10 H 6 O The balanced equation for the reaction that occurs when SO 2 dissolves in water is: ANSWER: B a) 3SO 2 + H 2 O 2HSO 3 + SO b) SO 2 + H 2 O H 2 SO 3 c) 3SO 2 + H 2 O HSO 3 + H + + S 2 d) SO 2 + H 2 O HSO 2 + OH Which of the following is a strong acid (check all that apply)? a) HCl b) CH 3 COOH c) HClO 4 d) HNO 3 e) HF, C, and D 8

9 32. What is the molecular weight (mass) of ferrocene, Fe(C 5 H 5 ) 2? a) b) c) d) What is the oxidation state of boron in boron trifluoride? a) 0 b) +1 c) +2 d) Consider the combustion of benzene: 2C 6 H 6(g) + 15O 2(g) 12CO 2(g) + 6H 2 O (l) If 25.0 g of benzene is mixed with 18.0 g of O 2(g) and allowed to react, how much CO 2 will be produced? a) 43.0 g b) 28.7 g c) 84.5 g d) 19.8 g 35. If 5 moles of chlorine gas are reacted with 4 moles of sodium to make sodium chloride, which of the following statements is true (check all that apply)? a) chlorine is the limiting reagent, 1 mole of sodium will be left after the reaction b) sodium is the limiting reagent, 1 mole of chlorine will be left after the reaction c) chlorine is the limiting reagent, 6 moles of sodium will be left after the reaction d) sodium is the limiting reagent, 3 moles of chlorine will be left after the reaction e) the reaction is stoichiometric, all of the sodium and chlorine are consumed 36. Which molecule is expected to be the most polar? a) CO 2 b) O 2 c) CH 4 d) SnCl 2 e) PCl 5 9

10 37. An aqueous solution labeled "potassium permanganate" contains the ions: a) K + and MnO 4 - b) P 3+ and MnO 3 - c) K + and MnO 2 - d) Pt 2+ and MnO How many grams of Na 2 SO 4 are needed to make ml of a M solution of Na 2 SO 4? a) g b) g c) g d) g ANSWER: E (12.70 g are needed) 39. Which of the following has the highest (most endothermic) first ionization energy? a) Be b) B c) C d) N e) O 40. The typical wavelength of UV-B ultraviolet light is 300 nm. Which of the following bonds can be broken by a single photon of this energy (average bond energies are given next to each bond)? Check all that apply. a) C-N (305 kj/mol) b) C-O (358 kj/mol) c) C=O (745 kj/mol) d) N N (945 kj/mol) and B (the energy works out to 400 kj/mol) 10

11 41. Which of the following ions has the largest radius? a) K + b) Ca 2+ c) As 3- d) Se 2- e) Br What is the energy needed to ionize (completely remove an electron from) a hydrogen atom? a) 91.2 nm b) nm c) nm d) 1.84 nm (OK if they put E; problem worded wrong asking for E not wavelength) 43. Consider the reaction: 2CO (g) + 2NO (g) 2CO 2(g) + N 2(g) In the balanced equation, how many moles of N 2 are produced per mole of CO reacted? a) 0 b) 0.67 c) 1 d) 1.5 ANSWER: E (it is 0.5) 44. Which compound below contains 39.2 % Cl by mass? a) NaCl b) NaClO c) NaClO 2 d) NaClO 3 e) NaClO 4 11

12 45. The Direct Process, also called the Rochow Process, is the most common method used to prepare organosilicon compounds such as silicone on an industrial scale. It uses an alkyl halide and elemental silicon as reactants. One balanced reaction for the process is: 2CH 3 Cl (g) + Si (s) (CH 3 ) 2 SiCl 2 (s) If 50.0 g of CH 3 Cl are reacted with excess Si and 33.0 g of (CH 3 ) 2 SiCl 2 are produced, what is the percent yield of the reaction? a) 63.9 % b) 66.0 % c) 25.8 % d) 51.6 % 46. In the following reaction: 2KClO 3 + 3C 3CO 2 + 2KCl How many moles of electrons does 1 mole of the KClO 3 oxidizing agent receive? a) 2 b) 4 c) 6 d) What is q in Joules when 35.0 g of liquid water is heated from 25.0 C to 80.0 C? a) 8050 J b) 1930 J c) 15,400 J d) 8000 J 48. Calculate the enthalpy change (ΔH) in the combustion of kg of ethanol, given the standard enthalpy of combustion of ethanol (C 2 H 6 O (l) ) is kj/mol. The reaction is: a) -28,900 kj b) -303,000 kj c) kj d) kj CH 3 CH 2 OH (l) + 3O 2(g) 2CO 2(g) + 3H 2 O (l) 12

13 49. Given the following thermochemical data: Process Enthalpy, kj/mol Ca (s) Ca (g) H f (Ca (g) )= +178 S (s) S (g) H f (S (g) )= +279 Ca 2+ (g) + 2e - Ca (g) H rxn = Ca + (g) + e - Ca (g) H rxn = -590 S (g) + 2e - S 2- (g) H rxn = 332 S (g) + e - S - (g) H rxn = -200 Ca (s) + S (s) CaS (s) H f (CaS (s) )= -482 What is the enthalpy change for the following reaction: Ca 2+ (g) + S 2- (g) CaS (s) ΔH =? a) kj b) kj c) kj d) -207 kj 50. A table of bond energies is given below. From this data, what is ΔH rxn for the chlorination of methane (CH 4 ) to form chloroform (HCCl 3 ), shown below. Average Bond Energies, kj/mol Bond Energy Bond Energy H-H 432 C=O (for CO 2 ) 799 H-Cl 427 C=O 745 C-H 413 Cl-Cl 243 C-C 347 C-Cl 339 O=O 498 O-H 467 a) +83 kj b) kj c) -330 kj d) -207 kj 13

14 51. Which of the following song titles best describes your experience with Chem 6A? a) Tell Me Why Taylor Swift b) Bad Romance Lady GaGa c) Hot N Cold Katy Perry d) Double Rainbow The Gregory Brothers (write-in on back of scantron form) 14