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Chemistry 1201 Section 4
Spring 1999
Professor Russo
Exam #6
Type of exam: In class. You can use your cheat sheet and a calculator. In most cases, vital
constants and conversion factors are supplied. If you cannot see the periodic table from where
you are seated, ask one of the proctors to provide you a periodic table.
Covers: Chapter 6, 7, 8 and 9. Problems are modifications of the take-home exams or other
assigned problems.
Duration: 80 minutes.
Value: 95 points. Each question is 6 points and I am giving out 5 points just because of the
typographical errors on the previous Exam. Remember….you are trying to earn 700 points on
all in-class and take-home exams. After this, we will have had 570 total possible points.
Instructions: Mark your answers on a LARGE scantron using a #2 pencil. Be sure to write
and bubble in your name and student ID number! Fill out the scantron just before turning it
in. You can mark the right answers directly on this exam until you are sure you have the
answer you wish to select.
Correct Answers: Posted outside my office eventually; Proctors should show them after all
exams have been picked up. So stick around if you finish early!
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Question #1. (based on BLB #6.14; similar to Exam 3, question #5.) What is the smallest
increment of energy in calories (be careful) that can be emitted or absorbed at a wavelength of
6328 Å? (Remember that 1 Å = 1 x 10-10 m; also h = 6.63 x 10-34 Joule-s ; c = 3 x 108 m/s ;
1 cal = 4.184 J)
a)
1.88 X 10-10
b)
7.51 x 10-20
c)
3.74 x 10-16
d)
3.14 x 10-19
e)
1.89 x 1030
Question #2. (BLB Text 6.32b; similar to Exam 3, Question #7.) The hydrogen atom can
absorb light of wavelength  = 121.6 nm. This is powerful UV radiation, so you can assume
that the initial quantum number for this transition is 1. What is the final value, nf? The
Rydberg equation is:
 1
hc
1 
E 
 ( Rh ) 2  2 
n


 i nf 
( h = 6.63 x 10-34 Joule-s, c = 3 x 108 m-s-1 and Rh = 2.18 x 10-18 J).
a)
b)
c)
d)
e)
1
2
3
4
5
Chem 1201 Sec. 4
Exam #6
Page 1
Question #3. (similar to BLB 6.75, or Exam 3, Question #9). Consider a laser that produces
1.8 Watts at 488 nm. How many photons does it emit in one minute? Express your answer in
mol. (Remember: 1 mol of something is 6.02 x 1023 and Power in Watts is given by energy in
Joules divided by time in seconds: P = E/t. One Watt = 1 Joule per second.)
a) 4.40 x 10-4
b) 2.65 x 1020
c) 4.40 x 105
d) 2.65 x 10-4
e) 7.33 x 10-6
Question #4. (based on 6.66) The correct electron configuration for Tc is best represented by:
a)
[Kr]
b)
c)
d)
5s
4d
5s
4d
[Kr]
[Xe]
6s
5d
5s
5d
[Kr]
Question #5. (similar to on 8.88, assigned & worked in class) Draw the best structure for
nitrate ion, NO3-1. For the central nitrogen atom, the formal charge and oxidation numbers are,
respectively:
a) +1, +5
b) 0, +3
c) –2, +3
d) +2, +3
e) -1, +5
Question #6. (based on 8.64) True or False: the sole carbon on methanol, CH3OH, has a
tetrahedral electron symmetry, so it is a nonpolar molecule.
a) True, methanol has no polarity.
b) False, methanol is polar.
Chem 1201 Sec. 4
Exam #6
Page 2
Question #7. (based on 9.20) Which of the following molecules are polar?
I) SiCl4
a)
b)
c)
d)
e)
II) IF
III) SO2
IV) PCl3
V) SF6
I and V
II only
II and III and IV
All of them
None of them
Question #8. (based on BLB 9.16) Give the approximate value for the indicated C-N-H bond
angle shown in ethylamine, shown below (it is not drawn in any kind of 3D perspective right
now; time to use those electron domain concepts).
H
a)
b)
c)
d)
H
H
H
C
C
N:
H
H
H
o
90
109.5o
120o
180o
Question #9. (based on BLB 9.16) Give the approximate value for the indicated C-C-N bond
angle in ethylamine.
H
H
H
H
a)
b)
c)
d)
90o
109.5o
120o
180o
C
C
N:
H
H
H
Question #10. (based on BLB 6.34) A carbon atom (1.993 x 10-23 g) with a deBroglie
wavelength of 1.17 x 10-13 m has what velocity? (Remember: h = 6.63 x 10-34 Joule-s and
1 Joule = 1 kg-m2-s-2) Hint: be very careful with your units!
a) 8.52 x 108 m/s
b) 3.17 x 106 m/s
c) 2.84 x 105 m/s
d) 1.93 x 10-5 m/s
e) 8.17 x 104 m/s
Chem 1201 Sec. 4
Exam #6
Page 3
Question #11. (based on BLB 7.14) Arrange the following in order of increasing atomic
radius: B, Ca, Ga, Cs. Put the largest atom on the right, smallest on the left.
a) B < Ca < Ga < Cs
b) Cs < B < Ca < Ga
c) Ga < Cs < B < Ca
d) B < Ga < Ca < Cs
Question #12. (based on BLB 7.23) Which has the higher first ionization energy, Si or Pb?
a) Si
b) Pb
Question #13. (based on BLB 7.23) Which has the higher first ionization energy, In or Te?
a) In
b) Te
Question #14. True or false. Other things being equal, a polar molecule has a lower boiling
point than a nonpolar molecule. (Hint: compare actual molecules we discussed in class)
a) True
b) False
Question #15. (BLB 9.40) By now, you may want an aspirin! So here it is:
H
H
3
O
C
O
H
C
2
C
H
1
C
C
H
O
H
C
C
O
H
H
For the actual three-dimensional molecule, the bonds labeled 1, 2 and 3 have what angles,
respectively?
a)
b)
c)
d)
e)
109.5o, 109.5o, 109.5o
180o, 120o, 180o
109.5o, 72o, 180o
120o, 120o, 109.5o
120o, 120o, 180o
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Chem 1201 Sec. 4
Exam #6
Page 4
There! You have survived three in-class exams. Things to note:
 The assigned problems re-appeared.
 If you are only working the take-home exams, you will get wiped out!
 Only by working the assigned problems and the take-home exams can you work quickly
enough to do well!
 I hope you are truly convinced. Give me two hours a day, ask questions promptly when
you are confused, and I can almost guarantee you will do OK.
 The material in the course now switches to chemical reactions. Study very hard the next
few weeks.
 Remember, ALL THE PROBLEMS are assigned for Chapter 3.
-----------------------------------------------------------------------------------------------------------------USE THE REST OF THIS PAGE AND THE BACK FOR CALCULATIONS
Chem 1201 Sec. 4
Exam #6
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