CHM134 General Chemistry I
Final Examination, Fall 2008
Name Answer Key
1. 2 pts. Report the result of the following calculation to the correct number of significant digits.
(231.4 – 229.4) / 2.3 = 0.87
2. 2 pts. Convert the following temperatures:
312 K = 39 oC
84 oF = 29 oC
3. 2 pts. What is the mass in grams of an object that has density 15.75 g/mL and a volume equal to 45
mL? 710 g
4. 2 pts. What mass in grams does 2.78 moles of iron (Fe) have? 155 g
5. 3 pts. 27Al3+ is an atom with 13 protons, 14 neutrons, and 10 electrons.
6. 2 pts. How many carbon atoms are contained in 15.0 grams of C2H6? 6.01 x 1023
7. 2 pts. What is the mass % of copper (Cu) in CuSO4?
39.81 %
8. 2 pts. What is the volume (in cm3) of a room that is 8.0 ft high, 35 ft wide, and 44 ft long? 3.5 x 108 cm3
9. 3 pts. What is the empirical formula of a compound that is 54.53 % C, 9.15 %H, and 36.32 % O by mass?
C2H4O
10. 5 pts. Provide a correctly spelled name for each of the following:
Ni(NO3)2
nickel (II) nitrate
Li2SO4
lithium sulfate
N2H4
dinitrogen tetrahydride
SiO2
silicon dioxide
KClO2
potassium chlorite
11. 5 pts. Provide a correct chemical formula for each of the following:
cobalt (II) chloride
CoCl2
potassium sulfite
K2SO3
sulfur hexafluoride
SF6
ammonium phosphate
(NH4)3PO4
iron (III) oxide
Fe2O3
12. 12 pts. Consider the following balanced chemical equation:
C4H8O2 + 5 O2 Æ 4 CO2 + 4 H2O
Determine the percent yield if the reaction produces 32.2 grams of carbon dioxide when 91.7 grams
of C4H8O2 are burned in an excess of oxygen.
17.6
%
13. 12 pts. Consider the following balanced chemical equation:
2 AgNO3 (aq) + Na2SO4 (aq) Æ 2 NaNO3 (aq) + Ag2SO4 (s)
What is the maximum mass (in grams) of Ag2SO4 that can form when 125.0 mL of a 2.5 M AgNO3
solution is combined with 100.0 mL of a 2.0 M Na2SO4 solution?
49 g Ag2SO4
14. 2 pts. Circle any of the following that are soluble in water:
NaOH
BaSO4
AgCl
Pb(NO3)2
NH4Br
FeS
15. 4 pts. Consider the following balanced chemical equation:
Sn (s) + 4 HNO3 (aq) Æ SnO2 (s) + 4 NO2 (g) + 2 H2O (g)
N is the atom being reduced, Sn is the atom being oxidized. The reducing agent is Sn
and 4 electrons are transferred in the equation as written.
16. 2 pts. At most, there are
4 different orbitals that can have n=2 in a given atom.
17. 2 pts. At most, there are 10 different electrons that can have n=3 and
18. 2 pts. Green light has a
higher
l =2 in a given atom.
frequency than red light.
19. 2 pts. A frequency of 2.78 x 1015 Hz would have a wavelength equal to 108
nm.
20. 4 pts. The energy levels of the hydrogen atom are given by E =
− 2.18 × 10 −18 J
. Calculate the
n2
wavelength of light [in nm] emitted when atomic hydrogen drops from an n=3 to an n=2 level.
λ = 656 nm
21. 2 pts. The angular momentum (l) quantum number describes the shape of the orbital while the
magnetic (m) quantum number gives its orientation.
22. 2 pts. Circle which has the greatest first ionization energy: Na
K
Rb
23. 2 pts. Circle which has the greatest first ionization energy: N O F
24. 2 pts. An atom of Si has
4
valence electrons.
25. 2 pts. All alkaline earth metals have
2
valence electrons.
26. 4 pts. Write electron configurations for each of these (you may abbreviate core electrons):
N:
1s2 2s2 2p3
Sc:
[Ar] 4s2 3d1
Ag:
[Kr] 5s1 4d10
Hg:
[Xe] 6s2 4f14 5d10
27. 2 pts. Circle which one of these has the largest radius: Na
P Cl
28. 2 pts. Circle which one of these has the largest radius: O2-
Ne
Mg2+
29. 24 pts. In the first column, draw a Lewis Dot structure for each species. In the second column,
provide a 3D sketch of the species that includes estimated bond angles and the name of the shape.
The first one is done for you as an example.
LEWIS DOT STRUCTURE
VSEPR Sketch
CH4
H
H
109.5 o
H
C
H
C
H
H
H
H
shape name:
tetrahedral