CHEM 3: Final Exam—Fall 2014
Name:____________________________________________
INSTRUCTIONS: On the front and back of the scantron, fill out your name and 7-digit student ID. Fill in this
information from left to right in the provided fields, and bubble in the values on the scantron. 1 point will be
deducted from your exam grade for incomplete or erroneous filling of the scantron.
Please read each question carefully. Where the question specifies “MARK ALL THAT APPLY”, you MIGHT need to
select more than one answer on the scantron.
1.
How many significant figures are in a volume measurement reported as 0.01090 L?
A. 2 sig figs
B. 3 sig figs
C. 4 sig figs
D. 5 sig figs
E.
6 sig figs
2.
Convert 95 oC to the equivalent temperature in Kelvin.
A. -178.15 K
B. 370 K
C. 368 K
D. 368.1 K
E.
368.15 K
3.
Convert this number to PROPER scientific notation: 0.000870 x 10-5
A. 8.7 x 10-4
B. 8.7 x 104
C. 8.7 x 109
D. 8.7 x 10-9
E. 8.7 x 10-20
4.
An electromagnetic wave has a wavelength of 0.594 µm. Express this wavelength in nanometers (nm).
A. 0.000594 nm
B. 1.98 x 10-15 nm
C. 178 nm
D. 594 nm
E. 5.05 x 1014 nm
5.
Bluetooth technology uses microwaves with a frequency of 2.4 GHz. Based on this frequency of electromagnetic
radiation, what is the wavelength of these microwaves (in m).
Hint: 1 GHz = 1 gigahertz = 1 x 109 Hz = 1 x 109 s-1
A. 0.12 m
B. 1.2 x 108 m
C. 7.2 x 108 m
D. 8.0 m
E. 8.0 x 10-9 m
6.
Convert 0.0821 L·atm/mol·K to the equivalent constant expressed in units of mL·psi/mol·K. As needed, you may
consult the back page of the exam for any relevant conversion factors.
A. 1.21 x 103 mL·psi/mol·K
B. 0.00121 mL·psi/mol·K
C. 5.59 x 10-6 mL·psi/mol·K
D. 5.59 mL·psi/mol·K
E. 121 mL·psi/mol·K
7. What is the mass of 0.159 cm3 of solid gold metal (Au)?
Information that MIGHT be useful: Gold has a density of 19.32 g/cm3, and an atomic mass of 196.96 amu.
A. 605 g
B. 3.07 g
C. 31.3 g
D. 0.00823 g
E. 0.000807 g
8. What is the mass of 0.250 moles of magnesium chloride (MgCl2)?
Information that MIGHT be useful: MgCl2 has a density of 2.32 g/cm3 and a molar mass of 95.2 g/mol.
A. 0.00263 g
B. 14.9 g
C. 23.8 g
D. 59.75 g
E. 95.2 g
9. How many atoms of iron are in 12.9 mol of iron?
Information that MIGHT be useful: Iron has a density of 7.87 g/mL, and an atomic mass of 55.85 amu.
A. 7.77 x 1024 atoms
B. 9.87 x 1023 atoms
C. 6.022 x 1023 atoms
D. 1.39 x 1023 atoms
E. 5.51 x 1025 atoms
10. The vast majority of the MASS in a single atom is accounted for in the _____________________________.
A. nucleus
B. electrons
C. charge
D. It depends on whether it’s a solid, liquid or gaseous element.
11. The vast majority of the VOLUME of a single atom is occupied by the _____________________________.
A. nucleus
B. electron cloud
C. protons
D. neutrons
E. It depends on whether it’s a solid, liquid or
gaseous element
12. Which isotope of Fluorine (C) has the same number of PROTONS as Oxygen-18 (O with mass number = 18)?
A. Fluorine-10
B. Fluorine-16
C. Fluorine-17
D. Fluorine-18
E. None of the above.
13. Which isotope of Potassium (K) has the same number of NEUTRONS as Argon-40 (Ar with mass number = 40)?
A. Potassium-22
B. Potassium-19
C. Potassium-40
D. Potassium-41
E. None of the above.
14. Naturally occurring Cerium consists of the four isotopes below, and has an average atomic mass of 140.12 amu.
Based ONLY on this information, which isotope is most abundant in nature? If this information alone is NOT
sufficient to identify the most abundant isotope, select E.
Cerium Isotope
Isotopic Mass (amu)
A.
Cerium-136
135.91
B.
Cerium-138
137.91
C.
Cerium-140
139.91
D.
Cerium-142
141.91
E.
Cannot be determined from information provided. Mass spectrometry data would have to
be collected and analyzed.
15. Assign the identity of each orbital below (I., II., & III.).
A.
B.
C.
D.
E.
I.→2p
I.→1s
I.→1s
I.→3d
I.→1s
II.→3p
II.→2s
II.→2p
II.→4d
II.→1p
III.→4p
III.→3s
III.→3d
III.→5d
III.→1d
16. How many total electrons are present in a strontium CATION, Sr2+ ?
A. 2
B. 8
C. 36
D. 38
E. 40
17. Which set of quantum numbers below is forbidden, and NOT allowed?
A. n = 4, l = 3, ml = 3, ms = +1/2
B. n = 6, l = 1, ml = 0, ms = +1/2
C. n = 100, l = 40, ml = -10, ms = -1/2
D. n = 9, l = -5, ml = -7, ms = +1/2
E. n = 5, l = 3, ml = 1, ms = -1/2
18. What is the electron configuration of a neutral chlorine atom?
A. 1s21p62s22p7
B. 1s22s23s23p64s24p3
C. 1s22s22p63s23p5
D. 1s21p62s22p4
E. 1s22s22p62d7
19. How many valence electrons are in a diazonium CATION with the formula C6H5N2+ ?
A. 12
B. 13
C. 38
D. 39
E. 40
20. MARK ALL THAT APPLY: Each formula below has been assigned a name. Following the official rules of IUPAC
nomenclature, circle ALL the formulas with the CORRECTLY ASSIGNED chemical name.
Formula
Assigned name
A. Mg(NO3)2
→
magnesium nitrate
B. Cu2SO4
→
copper sulfate
C. Al2O3
→
dialuminum trioxide
D. Ca3N2
→
calcium (III) nitride
E. K3P
→
potassium phosphate
21. MARK ALL THAT APPLY: Circle ALL formulas below which represent IONIC compounds.
A. NH4NO3
B. P4O10
C. Mg3N2
D. CH3CO2CH3
E. FeSO3
22. MARK ALL THAT APPLY: Circle ALL formulas below which are reasonable EMPIRICAL formulas.
A. CH3CH2CH2CH3
B. CCl3CO2H
C. Fe3O4
D. N2O4
E. All of the above are reasonable empirical formulas.
23. An unknown hydrocarbon (CxHY) is composed of 82.65 % carbon by mass. What is the empirical formula of this
substance?
A. CH5
B. C10H4
C. C7H17
D. C2.5H
E. C2H5
24. Which Lewis dot structure below is the most reasonable representation for H3CNO2?
A.
B.
C.
D.
E.
25. Which Lewis dot structure below is the most reasonable representation for the bicarbonate ion, HCO 3-?
A.
B.
C.
D.
E.
26. Wow! Half way through and look at all you’ve learned! You’re doing great  Would you like a free point just because?
A. No thanks.
B. Yes, please.
C. Cannot determine from information provided.
27. Given the Lewis dot structure below, predict the ELECTRON geometry at the oxygen atoms.
A. Bent
B. Linear
C. Trigonal planar
D. Tetrahedral
E. Trigonal pyramidal
28. Given the Lewis dot structure below, predict the MOLECULAR geometry at the phosphorus atoms.
A. Bent
B. Linear
C. Trigonal planar
D. Tetrahedral
E. Trigonal pyramidal
29. Given the Lewis dot structure below, predict the Cl—Si—Cl bond angle in SiCl2H2?
A. 90o
B. 109.5o
C. 120o
D. 180o
E. Cannot determine from information provided.
30. Select the best depiction of the bond dipole moment and charge separation present for a P—Br bond.
A.
B.
C.
D.
E. None of these: P—Br is a NONPOLAR bond.
31. MARK ALL THAT APPLY: Based on the Lewis dot structures below and your understanding of VSEPR Theory, predict
which compounds would be NONPOLAR.
A.
B.
C.
D.
E. None of these
molecules are NONPOLAR.
32. A cylinder of gas initially contains 1.93 L of a gas at 14.7 psi & 270 K. How would the pressure change if the gas was heated
to 370 K and the volume of the cylinder increased (volume expanded)?
A. The pressure in the cylinder would increase.
B. The pressure in the cylinder would decrease.
C. The pressure in the cylinder would remain the same (constant).
D. It depends: the actual final volume would have to be specified.
33. A cylinder of gas initially contains 12.9 L of a gas at 43 psi & 298 K. How would the pressure change if the gas was cooled
and the volume of the cylinder increased to 22.7 L?
A. The pressure in the cylinder would increase.
B. The pressure in the cylinder would decrease.
C. The pressure in the cylinder would remain the same (constant).
D. It depends: the actual final temperature would have to be specified.
34. How many moles of helium gas are contained in a cylinder with a volume of 11.4 L, a pressure of 1.000 bar and a
temperature of 137 K?
A. 0.250 mol
B. 0.500 mol
C. 1.00 mol
D. 2.00 mol
E. 4.00 mol
35. Which gas below would have a density of 2.82 g/L at STP?
A. CH4 (molar mass: 16 g/mol)
B. CO2 (molar mass: 44 g/mol)
C. He (molar mass (4 g/mol)
D. SO2 (64 g/mol)
E. O2 (32 g/mol)
36. If the reaction below was performed inside a container with a fixed volume and temperature, how would the pressure
change over the course of the reaction?
2 C8H18(g) + 25 O2(g) → 16 CO2(g) + 18 H2O(g)
A.
B.
C.
D.
The pressure would increase.
The pressure would RAPIDLY decrease due to the formation of water vapor.
The pressure would not change.
Not enough information provided: the exact conditions (volume & temperature) would need to be specified.
37. Consider the reaction below:
P4(s) + 5 O2(g) → P4O10(s)
What mass of white phosphorus, P4(s), would be needed to fully react with 22.70 L of oxygen gas (O2) at STP?
A. 30.97 g
B. 6.194 g
C. 24.78 g
D. 123.9 g
E. 619.4 g
38. Assuming all gases are at 758 mmHg and 25 oC, what volume of sulfur dioxide gas would be needed to fully react with 8.0 L
of oxygen gas according to the equation below?
2 SO2(g) + 3 O2(g) → 2 SO3(g)
A. 5.3 L
B. 8.0 L
C. 12 L
D. 22.7 L
E. 68.1 L
39. Predict the precipitate likely to form from mixing silver (I) sulfate with sodium phosphate.
A. NaNO3(s)
B. AgPO4(s)
C. (NO3)3PO4(s)
D. Ag3PO4(s)
E. AgNa(s)
40. When properly balanced (with the smallest whole number coefficients), what is the stoichiometric coefficient on the
oxygen molecules (O2) in the reaction below?
_____ CH3CH2CH2CO2H(l) + _____O2(g) → _____ CO2(g) + _____ H2O(g)
A.
B.
C.
D.
E.
5
6
21
42
None of the above
41. Calculate the theoretical yield of nitrogen gas (N2(g) in grams) if 3.00 moles of sodium azide, NaN3, decompose
according to the equation below.
2 NaN3(s) → 2 Na(s) + 3 N2(g)
A.
B.
C.
D.
E.
42.0 g
56.0 g
63.0 g
84.1 g
126 g
42. What is the mass percent of a solution formed by dissolving 10. g of sodium chloride (NaCl) in 90. mL of water? Assume the
density of the water is 1.00 g/mL.
A. 0.11 %
B. 9.1 %
C. 10. %
D. 11 %
E. 100 %
43. How many moles of CHLORIDE ions are present in 750 mL of an aqueous solution of 4.0 M MgCl2?
A. 3.0 moles
B. 4.0 moles
C. 6.0 moles
D. 7.5 moles
E. 8.0 moles
44. What is the pH of a 1.5 x 10-2 M aqueous solution of HCl (a strong acid)?
A. pH = 0.015
B. pH = 1.82
C. pH = 2.00
D. pH = 2.82
E.
pH = 3.15
45. What is the concentration of hydrogen ions, [H+], in a sodium hydroxide solution with a pH = 8.50?
A. 5.0 x 10-8 M
B. 8.0 x 10-5 M
C. 3.2 x 108 M
D. 3.2 x 10-9 M
E. 0.929 M
46. A 1.00 mL solution of nitric acid (HNO3) with a pH of 1.00 is diluted to a total volume of 10.0 L. What is the pH of this
solution after the dilution?
A. The pH would NOT change with dilution.
B. pH = 0.50
C. pH = 3.00
D. pH = 4.00
E. pH = 5.00
47. In the reaction below, the product CH3NH3+ is _____________________________.
CH3CO2H + CH3NH2 → CH3NH3+ + CH3CO2A.
B.
C.
D.
E.
the conjugate base of CH3NH2
the conjugate acid of CH3NH2
the conjugate base of CH3CO2H
neither an acid nor a base
48. Consider the double replacement reaction below:
Pb(NO3)2(aq) + 2 NaCl(aq) → 2 NaNO2(aq) + PbCl2(s)
If 45.9 mL of 0.774 M NaCl solution is required to fully titrate a lead (II) nitrate solution, how much solid precipitate would
form (in moles) at the end of the titration?
A. 0.0178 moles
B. 0.0355 moles
C. 0.0593 moles
D. 0.0711 moles
E. 16.9 moles
49. If 15.00 mL of aqueous hydrochloric acid, HCl(aq), requires 25.12 mL of 0.1000 M NaOH, calculate the concentration of the
HCl in moles/L, [HCl].
A. 0.05971 M
B. 0.1675 M
C. 0.3768 M
D. 0.5971 M
E. 1.675 M
50. Consider the acid-base reaction below:
3 Mg(OH)2(aq) + 2 H3PO4(aq) → 6 H2O(l) + Mg3(PO4)2(s)
Consider the mixing of 30.0 mL of 3.00 M aqueous magnesium hydroxide solution with 30.0 mL of 2.00 M H3PO4 solution.
Under these conditions, what would be the limiting reagent?
A. Mg(OH)2(aq)
B. H3PO4(aq)
C. H2O(l)
D. Mg3(PO4)2(aq)
E. There would be no limiting reagent. Everything would fully react.
EXTRA CREDIT: 25 points
Data from the Mauna Loa Observatory in Hawaii indicate the global concentration of carbon dioxide in the atmosphere – the primary
cause of human-driven climate change – has recently reached 400 parts per million (ppm) for the first time in recorded history. This is
100 ppm higher than any time in the last 1 million years.
According to the U.S. Energy Information Association (EIA), the global combustion of gasoline (mostly C8H18) stands at roughly
22.0 x 109 barrels per year. Assuming all of the carbon dioxide generated from burning this gasoline enters the atmosphere (but
neglecting other sources of CO2), calculate the expected annual rise in carbon dioxide concentrations in parts per million.
Information that might be useful:
 1 barrel = 31.5 gallons
 1 gallon = 3.78 L
 Density of octane (C8H18) = 0.719 g/mL
 Boiling point of octane = 125 oC
 Solubility of octane in water: 0.007 mg/L at 20 oC
 Density of solid carbon dioxide = 1562 kg/m3 at 1 atm & -78.5oC
 Solubility of carbon dioxide in water: 1.45 g/L at 25 oC & 100 kPa
 Mass of the Earth’s atmosphere: 5.1 x 1018 kg
 Volume of Earth’s atmosphere: 4.2 x 109 km3
 Composition of Earth’s atmosphere:
o 78.09 % N2
o 20.95 % O2
o 0.93 % Ar
o 0.04 % CO2
o 0.01 % other gases
FINAL EXAM REFERENCE INFORMATION:
𝑫𝒆𝒏𝒔𝒊𝒕𝒚 =
𝑀𝑎𝑠𝑠
P1V1 = P2V2
𝑉𝑜𝑙𝑢𝑚𝑒
P1/T1 = P2/T2 V1/T1 = V2/T2 V1/n1 = V2/n2
PV=nRT, where R = 0.08206 L·atm/mol·K = 62.37 L·torr/mol·K = 8.314 L·kPa/mol·K
Temperature Conversion: Kelvin = oC + 273.15
PRESSURE CONVERSIONS: 1.00 atm = 14.7 psi = 760. mmHg = 101.325 kPa = 1.013 bar = 760 torr
1.00 bar = 750.06 torr = 0.987 atm
At STP: Pressure = 1.000 bar, Temperature = 273 K & 1 mole of gas = 22.7 L
Average atomic mass = (isotopic mass)∙(isotopic abundance)
1 mole = 6.022 x 1023 particles
c = λ·ν
Molarity = (# of moles)/(volume in liters)
Summing over all isotopes.
1 cm3 = 1mL
where c = 2.9979 x 108 m/s
Mass % = (Mass of Solute)/(Mass of Solution) x100
Ppm = (Mass of Solute)/(Mass of Solution) x 106
pH = -log[H+]
Dilution Problems: M1V1 = M2V2
Table of Electronegativities