Chemistry 111 Sect. 3
Final Exam
December 19, 2000
Name: ________________________________________________
Student #: ________________________________________________
Please put your name and student number on all pages in case they become separated. The
last page of the exam has some useful information. The exam lasts 120 minutes. There are a
total of 340 points, 85 from each section of the course. The portion of the course that the
question covers is noted to the left of the question number. Please show all your work. I can
only give partial credit if I can see your work.
MULTIPLE CHOICE QUESTIONS
Place an X in the box corresponding to the correct answer.
section
1
1. (15 pts) How many electrons are in the ion 33S2-?
o
o
o
o
o
1
18
33
35
14
16
17
33
35
3. (15 pts) An element has the valence electron configuration of ns2np2. This element would
be found in periodic group:
o
o
o
o
o
1
16
2. (15 pts) How many neutrons are in the ion 33S2-?
o
o
o
o
o
2
14
2
IVA
IVB
VIA
VIB
VIIIA
3
4
Page 1
T
Chemistry 111 Sect. 3
Final Exam
December 19, 2000
2
4. (15 pts) When an electron in a hydrogen atom undergoes a transition from n = 5 to n = 2
o
o
o
o
o
4
energy is given off as visible light.
an ultraviolet photon is absorbed.
four colors are observed.
16.0 g/mol
18.4 g/mol
40.0 g/mol
53.3 g/mol
160 g/mol
Left front
Left rear
Right front
Right rear
All are the same
7. (10 pts) What is the volume of a tire?
o
o
o
o
o
1
the hydrogen atom becomes a helium atom.
6. (10 pts) In which tire do the gas molecules or atoms have the greatest rms speed?
o
o
o
o
o
4
a continuous spectrum of light is produced.
The following information pertains to questions 5 - 7:
Each of the four tires of a car is filled with a different gas. Each of the tires has
the same volume and each is filled to the same pressure, 3.0 atm, at the same
temperature, T = 25 °C. The tires are filled as follows:
• Right front: 80.7 g of Ne
• Left front: 112 g of N2
• Left rear: 16.0 g of He
• Right rear:
160 g of an unknown gas
5. (10 pts) What is the molecular mass of the unknown gas?
o
o
o
o
o
4
Name: ________________________________________________
Student #: ________________________________________________
2
0.25 L
1.0 L
4.0 L
16 L
33 L
3
4
Page 2
T
Chemistry 111 Sect. 3
Final Exam
December 19, 2000
1
8. (10 pts) The name of the compound Ca(NO3)2 is:
o
o
o
o
o
2
calcium nitrite
copper nitrate
copper nitride
H+ + C2H3O2- → HC2H3O2(l)
4 H(g) + 2 C(s) + 2 O(g) → HC2H3O2(l)
2 H2(g) + 2 C(s) + O2(g) → HC2H3O2(l)
HC2H3O2(l) → 4 H(g) + 2 C(s) + 2 O(g)
HC2H3O2(l) + 2 O2(g) → 2 CO2(g) + 2 H2O(l)
Fe(OH)3(s) + 3 NO3-(aq) → Fe(NO3)3(aq) + 3 OH-(aq)
Fe(OH)3(s) +3 H+(aq) + 3 NO3-(aq) → Fe(NO3)3(aq) + 3 H2O(l)
Fe(OH)3(s) + 3 H+(aq) → Fe3+(aq) + 3 H2O(l)
Fe3+(aq) + 3 OH-(aq) + 3 HNO3(aq) → Fe(NO3)3(aq) + 3 H2O(l)
Fe3+(aq) + 3 HNO3(aq) → Fe(NO3)3(aq) + 3 H+
11. (15 pts) The electron pair geometry around the central atom in NH3 is:
o
o
o
o
o
1
calcium nitride
10. (15 pts) The balanced net ionic equation that best represents the overall reaction that
would occur when insoluble iron(III) hydroxide and aqueous nitric acid are combined is
o
o
o
o
o
3
calcium nitrate
9. (15 pts) The standard enthalpy of formation of HC2H3O2 (l) is equal to ∆H° for which of
the following reactions?
o
o
o
o
o
1
Name: ________________________________________________
Student #: ________________________________________________
2
linear
trigonal planar
tetrahedral
trigonal bipyramidal
octahedral
3
4
Page 3
T
Chemistry 111 Sect. 3
Final Exam
December 19, 2000
3
12. (15 pts) The molecular geometry around the central atom in NH3 is:
o
o
o
o
o
4
bent
trigonal planar
tetrahedral
trigonal pyramidal
T-shaped
13. (15 pts) What is the orbital hybridization around the carbon atom in CO32- (Lewis
structure shown below)?
o
o
o
o
o
3
sp
sp2
sp3
.. C
:O
..
sp3d
sp3d2
..
O:
..
14. (15 pts) The atoms that make up phosgene (Cl2CO) have electronegativities that are
given below. For the orientation of the molecule as shown, what is the direction of the
molecular dipole moment?
o
o
o
o
o
C: 2.5
O: 3.5
(from C to O)
O
(from C to right Cl)
C
(from O to C)
Cl
(from C to left Cl)
Cl
The dipole moment is zero.
15. (15 pts) If 12.4 g of phosphorus reacts with sulfur to form 22.0 g of a compound of P and
S, what is the empirical formula of the compound?
o
o
o
o
o
1
2-
:O:
Cl: 3.0
1
Name: ________________________________________________
Student #: ________________________________________________
2
P2S
P2S2
P2S3
P3S4
P4S3
3
4
Page 4
T
Chemistry 111 Sect. 3
Final Exam
December 19, 2000
Name: ________________________________________________
Student #: ________________________________________________
MULTIPLE MULTIPLE CHOICE QUESTIONS
Place an X in the boxes corresponding to the correct answers. Any number of answers may
be correct, including none of them.
4
16. (10 pts) The molecular geometry of compound XF2 is shown below, where X is an unknown
element. Which of the following orbital hybridizations are possible for XF2?
o
o
o
o
o
4
2
F
sp
sp2
X
sp3
F
sp3d
sp3d2
17. (20 pts) Which of the following are true?
o
According to Valence Bond theory, pi bonds arise from overlap of unhybridized
atomic orbitals.
o
According to Kinetic Molecular theory, gas pressure in a container is due to
collisions of gas molecules with surfaces of the container.
o
According to the Ideal Gas law, the volume of a gas will decrease as temperature
decreases if pressure and number of molecules of the gas are held constant.
o
The sp2 hybrid orbitals formed from s, px and py atomic orbitals are 120 ° apart in the x-y
plane.
o
Rotation around double bonds is restricted.
18. (20 pts) Which of the following electron configurations does NOT represent a real element?
o
[Ne]4s23d1
o
1s3
o
[He]2s22p4
o
1s22s22p63s23p64s23d104p5
o
[Ar]4s23d1
SHORT ANSWER QUESTIONS
Answer in the spaces indicated.
1
2
3
4
Page 5
T
Chemistry 111 Sect. 3
Final Exam
December 19, 2000
Name: ________________________________________________
Student #: ________________________________________________
3
19. (20 pts) Draw the Lewis structure for O3. Is this a resonance structure?
3
20. (20 pts) What are the electronic and molecular geometries for H2S?
1
21. (15 pts) Answer the following questions for this redox reaction.
5 Fe2+(aq) + MnO4-(aq) + 8 H+(aq) → 5 Fe3+(aq) + _____ Mn2+(aq) + ____ H2O(l)
What is the oxidizing agent in this reaction? ___________
What is the stoichiometric coefficient for Mn2+(aq)? ____________
What is the stoichiometric coefficient for H2O(l)? ____________
What is the oxidation number for Mn in MnO4-(aq)? ____________
How many electrons are transferred in this reaction? __________
1
2
3
4
Page 6
T
Chemistry 111 Sect. 3
Final Exam
December 19, 2000
Name: ________________________________________________
Student #: ________________________________________________
4
22. (10 pts) We saw in lecture that two identical balloons at 25 °C, one filled with He and the
other with O2, leaked their gases at different rates. This effusion rate for the two different
gases can be made equal when the temperature of the He balloon is changed. Is that
temperature higher or lower than 25 °C ? What is that temperature? (Please show your work.)
2
23. (20 pts) Ethanol, C2H5OH, has a molar mass of 46.0 g/mol and boils at 78 °C. How
much heat energy in joules is required to heat 92 g of liquid ethanol from 40 °C to the boiling
point? How much more heat is required to convert the liquid completely to a vapor at 78 °C?
(The specific heat of liquid ethanol is 2.4 J/g•K and its enthalpy of vaporization is 40
kJ/mol.)
Heat liquid: ________________ J
1
2
3
4
Boil liquid: ________________ J
Page 7
T
Chemistry 111 Sect. 3
Final Exam
December 19, 2000
Name: ________________________________________________
Student #: ________________________________________________
Useful information
fc = grp # - ½(# bond e-) - (# LP e-)
∆Hrxn = Σ(bond ener)react - Σ(bond ener)prod
q = C m ∆T
q = (heat of fusion) m
∆H = qp
∆H0net = Σ (∆H0f)prod - Σ (∆H0f)react
∆H0net = Σ (∆H0rxn)
c = λν
E = hν
E = -Rhc/n2
λ = h/(m v)
Z* = Z - ninner electons
c = 3.0 × 108 m/sec
h = 6.6 × 10-34 J sec
Rhc = 2.2 × 10-18 J
me = 9.1 × 10-28 g
a0 = 0.0529 nm
NA = 6.02 × 1023 molecules/mol
2-linear, 3-trigonal planar, 4-tetrahedral
5-trigonal bipyramidal, 6-octahedral
R = 0.0821 L•atm/mol•K
PV = nRT
KE = kT = mu 2 / 2
3RT
urms = u 2 =
M
diffusion rate ∝ urms
d = m/V
PERIODIC TABLE OF THE ELEMENTS
IA
IIA
IIIB
IVB
VB
VIB
VIIB
VIIIB
IB
IIB
IIIA
IVA
VA
VIA
VIIA VIIIA
1
2
H
He
1.008
1
4.003
3
4
5
Li
Be
B
C
N
O
F
Ne
6.939
9.012
10.81
12.01
14.01
16.00
19.00
20.18
11
12
13
14
15
16
17
18
Na
Mg
Al
Si
P
S
Cl
Ar
22.99
24.31
26.98
28.09
30.97
32.07
35.45
39.95
19
20
21
22
K
Ca
Sc
Ti
39.10
40.08
44.96
37
38
39
Rb
Sr
85.47
55
7
8
9
10
24
25
26
27
28
29
30
31
32
33
34
35
36
V
Cr
Mn
Fe
Co
Ni
Cu
Zn
Ga
Ge
As
Se
Br
Kr
47.90
50.94
52.00
54.94
55.85
58.93
58.71
63.55
65.39
69.72
72.61
74.92
78.96
79.90
83.80
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
Y
Zr
Nb
Mo
Tc
Ru
Rh
Pd
Ag
Cd
In
Sn
Sb
Te
87.62
88.91
91.22
92.91
95.94
(99)
101.1
102.9
106.4
107.9
112.4
114.8
118.7
121.8
127.6
126.9
131.3
56
57
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
Cs
Ba
La
Hf
Ta
W
Re
Os
Ir
Pt
Au
Hg
Tl
Pb
Bi
Po
At
Rn
132.9
137.3
138.9
178.5
181.0
183.8
186.2
190.2
192.2
195.1
197.0
200.6
204.4
207.2
209.0
(209)
(210)
(222)
87
88
89
Fr
Ra
Ac
(223)
226.0
227.0
2
3
23
6
4
Page 8
I
T
Xe