MOCK FINAL – Chemistry 102
Significant figures
1. When the following calculation is performed, how many significant figures are in the correct answer?
(1.00866 – 1.00776) x (6.022 x 1023)
a) 1 b) 2 c) 3 d) 4 e) 6
Nomenclature
2. How many of the following formulas are written correctly?
I. strontium(II) chloride II. sulfur oxide
III. bromine(III) fluoride IV. potassium phosphide
a) 0 b) 1 c) 2 d) 3 e) 4
3. Which of the following have both names and corresponding formulas correct?
I. P2O5 phosphorus pentoxide II. NiClO2 nickel(II) hypochlorite
III. RbNO2 rubidium nitrate IV. ZnO2 zinc oxide
a) I and II b) I and III c) II and IV
d) I, III, and IV e) none of the above
Dimensional analysis
4. How many mm3 are in 0.035 L?
a) 0.035 b) 35 c) 350 d) 35,000 e) 350,000
Protons/neutrons/electron and atomic structure
5. An isotope of an atom X has a mass number of 81. If the most stable ion of the isotope forms the compound MgX2, how many neutrons does X have?
a) 35 b) 45 c) 46 d) 70 e) 81
6. Element Y has 15 protons. 31Y2- is isoelectronic with which atom below?
a) Al b) P c) S d) Cl e) Ar
Mass percent and moles
7. Rhenium has two isotopes, 185Re and 187Re, with an average atomic mass of 186.207 amu. If Rhenium is 62.60% 187Re, and the atomic mass of 187Re is 186.956 amu, what is the mass of 185Re?
a) 184.953 amu b) 185.000 amu c) 185.047 amu
d) 185.458 amu
8. Fungal laccase is 0.390 % Cu by mass. If one molecule contains 4 copper atoms, what is the molar mass of fungal laccase in g/mol?
a) 99 b) 254 c) 652 d) 1.63 x 104 e) 6.52 x 104
9. What is the mass of exactly 500 molecules of chloral hydrate, C2H3Cl3O2?
a) 2.75 x 10-22 b) 1.37 x 10-19 g c) 0.331 g
d) 165.4 g e) 82700 g
Empirical vs. molecular formulas
10. Adrenaline is 59.00 % C, 7.15 % H, 26.20 % O, and 7.65 % N by mass. What is its empirical formula?
a) C9H13NO3 b) C12H4N5O7 c) C7HO4N d) C8H14N2O3
11. Combustion of a compound of formula CxHyOz yields 11.53 g H2O and 37.56 g CO2 when 30.79 g of O2 are used. If the molar mass of the compound is between 50 and 100 g/mol, what is the molecular formula of the compound?
a) C5H8O3 b) C4H6O2 c) C4H3O4 d) C7H5O2
Stoichiometry
12. Chromium metal and elemental sulfur, S8(s), react to form chromium(III) sulfide. If 48.27 grams of product, which corresponds to a 76% yield, is obtained, what is the mass of S8 used in the reaction, assuming no limiting reagent? (Cr = 52.00 g/mol, S8 = 256.53 g/mol)
a) 81.38 g b) 30.52 g c) 23.19 g d) 17.63 g
13. In the reaction N2 + 3 H2 " 2 NH3, if 5 grams of each of the starting materials are used, the mass of unreacted reactant is
a) 0 g b) 3.92 g c) 4.28 g d) 4.64 g
Redox Reactions
A compound decomposes through the following unbalanced reaction in acidic media:
MnO2(s) " MnO4-(s) + Mn2+(s)
Balance this reaction and use the information to answer the following three (3) questions.
14. What is the reducing agent?
a) H+ b) H2O c) MnO2 d) MnO4- e) Mn2+
15. What is the coefficient of H+ in the balanced reaction?
a) 0 b) 2 c) 4 d) 8 e) 12
16. How many electrons are transferred in the balanced reduction half-reaction?
a) 1 b) 2 c) 3 d) 4 e) 5
Solubility
17. Consider the products of the following four unbalanced aqueous reactions:
I. AgNO3 (aq) + KCl (aq) " II. (NH4)2SO4 (aq) + Na2CO3 "
III. KOH + MnCl2 " IV. Pb(NO3)2 + BaCl2 "
Which will result in the formation of a precipitate?
a) I and II b) II and III c) III and IV
d) I, II, and III e) I, III, and IV
Ideal Gas Law
18. Wet He is placed into a balloon at 24.4 °C and a pressure of 765.3 mm Hg. What volume does this balloon occupy if the vapor pressure of water is 24.3 torr and the dried gas in the balloon weighs 0.128 g?
a) 0.801 L b) 0.0657 L c) 0.00105 L d) 3.21 L e) 0.775 L
19. Suppose the balloon in #18 is dipped in liquid nitrogen and cools down to
-196 °C. If the balloon resizes to 23 mL, what is the new pressure inside the balloon?
a) -272.8 atm b) 0.00880 atm c) 5.48 atm
d) 8.80 atm
20. At STP, the density of a gas is 1.783 g/L. What is the identity of the gas?
a) Ne b) Cl2 c) Ar d) Kr e) CH4
Kinetic Molecular Theory
21. Four 10 L flasks at STP contain Ar, He, CH4, and F2. Which of the following is TRUE regarding these?
a) The average kinetic energy of Ar is the highest.
b) Ar atoms have a higher velocity than F2 molecules.
c) CH4 behaves more ideally than the other gases under these conditions.
d) Helium is the least dense.
e) There are fewer moles of CH4 than F2.
Partial Pressures
22. A 4 L flask with 2.00 atm He is separated by a stopcock from a 2 L flask with 3.00 atm F2. What is the total pressure once the stopcock is opened at constant T?
a) 0.333 atm b) 2.33 atm c) 5.00 atm d) 6.00 atm
Mole Fractions
23. A 4 L flask with 2.00 g He is separated by a stopcock from a 2 L flask with 3.00 g F2. After the stopcock is opened, the total pressure is 600 mm Hg. What was the pressure of the helium inside the 4 L flask before it was opened?
a) 900 mm Hg b) 777 mm Hg c) 518 mm Hg d) 400 mm Hg
Effusion
24. Methane, CH4, effuses 1.414 times faster than another gas at the same temperature. What is the identity of the unknown gas?
a) N2 b) O2 c) F2 d) Ne e) Ar
Bohr model
25. What is the wavelength associated with light given off when the electron in a hydrogen atom jumps from n = 5 to n = 2?
a) 435 nm b) -435 nm c) 145 nm d) 652 nm e) 3040 nm
Electron configurations
26. How many of the following are correct ground state electron configurations?
Cr [Ar]4s14d5 Ge [Ar]4s23d104p2
Cl+ [Ne]3s23p8 Ta [Xe]6s24f105d3
a) 0 b) 1 c) 2 d) 3 e) 4
27. Which of the following atoms/ions has the largest number of unpaired electrons in the ground state? (Assume that transition metals lose 4s electrons first).
a) Mg b) Ar- c) Cu+ d) Zn2+ e) As3-
Quantum numbers
28. How many of the following quantum numbers correspond to a 4p electron?
I. n = 4, l = 1, ml = -1 II. n = 4, l = 2, ml = 1
III. n = 4, l = 0, ml = 0 IV. n = 4, l = 1, ml = 0
a) 0 b) 1 c) 2 d) 3 e) 4
Atomic Radius
29. Which of the following has the smallest atomic radius?
a) O b) Si c) Li d) Cs e) I
Ionization Energy
30. Which of the following is FALSE regarding ionization energy?
a) C < N b) C < O c) P < S d) Na < Li e) K+ < Ca2+
Lewis Structures, VSEPR
31. Which of the atoms below could be X?
a) N b) P c) O d) S e) Cl
32. Describe its shape and polarity:
a) tetrahedral, nonpolar b) trigonal bipyramid, polar
c) seesaw, polar d) square planar, nonpolar
e) trigonal pyramid, polar
33. How many of the following molecules are polar?
CH2Cl2 XeF4 BrF4- PO2+
a) 0 b) 1 c) 2 d) 3 e) 4
34. What is the highest formal charge on ozone, O3?
a) -2 b) -1 c) 0 d) +1 e) +2
35. An element in the ground state has one unpaired electron in the 5p atomic orbital. The element reacts with chlorine to form a neutral, covalent compound with 28 total valence electrons. Which of the following is this element?
a) In b) Sn c) Sb d) Te e) I
Hybridization
36. What is the hybridization and shape for the central atom in IF3?
a) sp3, trigonal planar b) sp3, tetrahedral c) dsp3, trigonal pyramidal
d) dsp3, T-shaped e) d2sp3, trigonal pyramidal
Crazy Effusion Question
37. Jack Bauer is having the worst day of his life, and is trapped in a corridor where HCl gas is being sent in through the vents behind him, and phosgene (COCl2) is being sent in from the other end of the corridor. If Jack runs to the exact point where the gases will mix, he’ll have the maximum time to plan his escape and live to see another 24 hours. How far down the corridor should he run?
a) ¼ the way b) ½ the way c) 2/3 the way d) ¾ the way
Massively Huge Organic Structure
The structure shown to the left is loratadine, otherwise known as the allergy medicine Claritin.
38. How many π-bonds belong in the structure to the left?
a) 5 b) 6 c) 7 d) 8 e) 9
39. What are the bond angles A and B?
a) 120°, 120° b) 109°, 109°
c) 120°, 109° d) 109°, 120°
e) 109°, 180°
IMF
40. Rank the following in terms of increasing vapor pressure:
F-F H-F H-Br Br-Br LiF CF4
a) LiF < HF < HBr < Br2 < CF4 < F2
b) F2 < CF4 < Br2 < HBr < HF < LiF
c) F2 < Br2 < CF4 < HF < HBr < LiF
d) Br2 < CF4 < HBr < F2 < LiF < F2
e) HF < LiF < Br2 < HBr < F2 < CF4
41. How many of the following list the strongest IMF for each compound?
N3- dipole-dipole BrF3 LDF
H2S hydrogen bonding CH2Br2 dipole-dipole
a) 0 b) 1 c) 2 d) 3 e) 4
Resonance
42. Which of the following are possible resonance structures for azide, N3-?
I. II.
III. IV.
a) I only b) II only c) IV only d) I and III e) II and III
Equilibrium
43. Consider the following equilibrium reaction:
C (s) + CO2 (g) D 2 CO (g)
Given the data at constant volume, below, which of the following statements about this equilibrium process is false?
Temperature (oC) % CO2 % CO
850 6.32 93.77
950 1.32 98.68
1050 0.37 99.63
1200 0.06 99.94
a) The reaction is endothermic
b) The value of K is greater than 1 at all of the temperatures listed
c) At 850o C, if the volume of the container is increased, the value of K increases
d) The value of K at 1200oC is larger than the value of K at 950oC
e) All of the above
44. Consider the following reaction in which all reactants and products are gases.
1.00 moles of A and 2.00 moles of B are placed in a 5.0 L container. After equilibrium has been established, 0.50 moles of D is present in the container. Calculate the equilibrium constant, K, for this reaction.
A (g) + 2 B (g) D 2 C (g) + D (g)
a) 0.15 b) 0.33 c) 1.0 d) 3.0 e) none of these
45. In the reaction:
HCN + HCO3- D CN- + H2CO3 K < 1
What is the strongest base in this system?
a) HCN b) H2O c) HCO3- d) H2CO3 e) CN-
Buffers
46. Which acid or base, when mixed with its conjugate, would make for a good buffer at pH 10.5?
Ka(HOC6H5) = 1.6 x 10-10 Ka(HOCl) = 3.5 x 10-8 Kb(CH3NH2) = 4.4 x 10-4
a) HClO4 b) HOC6H5 c) HOCl d) CH3NH2 e) NaOH
47. What is the pH of a solution made from 500 mL of 1.00 M HC2H3O2 and
1000 mL of 0.500 M C2H3O2- after 80.0 mL of 0.900 M NaOH is added?
(Ka of HC2H3O2 is 1.8 x 10-5)
a) 2.372 b) 2.657 c) 4.614 d) 4.744 e) 4.866
Titration Curves
Use the following titration curve to answer the next three (3) questions.
48. What type of titration does this curve represent?
a) weak acid (monoprotic) by strong base
b) weak acid (diprotic) by strong base
c) weak acid (triprotic) by strong base
d) weak base (dibasic) by strong acid
e) strong acid (diprotic) by strong base
49. If point B has a pH of 1.85, and point D has a pH of 7.19, what is the concentration of the major pH-determining species present at point C? (Assume the 5% rule holds.)
a) 1.41 x 10-2 M b) 3.02 x 10-5 M c) 6.46 x 10-8 M d) 6.21 x 10-10 M
50. If 200 mL of 0.4 M titrant were added to reach point E, and the total volume at point E is 350 mL, what was the initial concentration of the pH-determining species at point A?
a) 0.800 M b) 0.533 M c) 0.267 M d) 0.229 M e) 0.114 M
51. Suppose that this curve represents the titration of 100 mL of 0.1 M H2SO3 by
0.1 M NaOH. Calculate the pH at point E, given that Ka2 = 6.5 x 10-8.
a) 4.09 b) 7.50 c) 8.66 d) 9.85 e) 10.1