Chemistry 105: General Chemistry I
Dr. Gutow and Dr. Matsuno
Page 1
Exam 3 Form A
Spring 2004
1) Name ____________________________________
You are to keep this copy of the test. Your name is in case you leave it behind.
2) Use only a #2 pencil on the answer sheet.
3) Before starting the exam fill in your student ID# (not your SS#). Also fill in your name, course number and sign the
form.
4) Fill in the test form section (A, B, C or D). Which form you have is shown in the upper right corner.
5) Do not begin the exam until you are told to.
6) You will not get your scan sheet back!!! Circle your answers on this exam sheet and then transfer them to the scan
sheet when you are satisfied with all your answers. An answer key will be posted on the class web site and in the
glass case across from the lab after the exam.
7) If atomic weights are needed use only those from the attached periodic table.
8) No scratch paper is to be used. Use the back of this exam sheet if necessary.
9) There are 40 equally weighted questions on this exam. You have 90 minutes to complete them.
10) If you believe there is more than one correct answer pick only the best answer.
Useful Data
Constants
c = 2.998 x 108 m/s
h = 6.63 x 10-34 Js
density of H2 O = 1.00 g/mL
NA(Avogadro’s #) =6.022 x 102 3 particles•mol-1
R (gas constant) = 0.08206 L•atm•mol-1•K-1
e (charge on electron) = 1.60 x 10-19 C
1 D = 3.336 x 10-30 C•m
Units
2.54 cm = 1 inch
3.78 L = 1 gal
1 kg = 2.20 lb
1 % = 10,000 ppm
1 hr = 60 min
1 min = 60 seconds
1 amu = 1.660540 x 10-27 kg
molarity (M) = moles solute/L sol’n
molality (m)= moles solute/ kg solvent
Equations
% = fraction • 100 %
ppm = fraction • 106 ppm
T (in Kelvin) = 273.15 + T (in ˚C)
T (in Celsius) = (5/9) (T (in F) -32)
π = iMRT
∆Tb = imKb
∆Tf = imKf
actual yield (g)
% yield =100% # theoretical yield (g)
F.C. = V.E - (# non-bonding e-) - 1/2(# of bonding e-)
B.O. = 1/2 (bonding e- - antibonding e-)
µ = Qr
Chemistry 105: General Chemistry I
Dr. Gutow and Dr. Matsuno
Page 2
Exam 3 Form A
Spring 2004
1. How many valence electrons does Al3+ have?
a. one
b. two
c. three
d. six
e. zero
2. How many valence electrons are contained in BrO-?
a. 7
b. 6
c. 12
d. 13
e. 14
3. Indicate which of the following molecules contains a polar covalent bond
a. O2
b. N2
c. CN
d. H2
e. Cl2
4. How many shared electrons are there in the Lewis structure of CN-?
a. three
b. four
c. six
d. eight
e. octet
5. Which of the following properties is typically used to predict the type of bond that forms between two elements?
a. Electronegativity
b. Ionization energy
c. Atomic radius
d. Electron affinity
e. Powerpoint
6. Electronegativity increases from left to right across a period because of
a. the electronegativity trend rule
b. the increase of Zeff across the period due to increasing nuclear charge
c. the decrease of Zeff across the period due to shielding
d. the laws of conservation of electronegativity
e. cancellation of wave function due to shielding
Chemistry 105: General Chemistry I
Dr. Gutow and Dr. Matsuno
Page 3
7. Which element has the highest electronegativity?
a. Al
b. C
c. O
d. Cs
e. Rb
8. Which of the following lists the elements from smallest to largest atomic radius?
a. Cs, Rb
b. Si, As
c. Mg, He
d. Zr, Sc
e. none of the above
9. Indicate the element with the greatest first ionization energy.
a. Cs
b. Sr
c. S
d. O
e. Fr
10. Which of the following elements has the greatest electron affinity?
a. H
b. Sn
c. P
d. Sr
e. they are all the same at 0 kJ/mol
Exam 3 Form A
Spring 2004
Chemistry 105: General Chemistry I
Dr. Gutow and Dr. Matsuno
Page 4
Exam 3 Form A
Spring 2004
11. Which of the following bonds is definitely ionic?
Element
Electronegativity
C
2.5
O
3.5
H
2.1
Li
1.0
a. Li-C
b. Li-H
c. Li-O
d. Li-Li
e. C-O
12.A resonance structure indicates that there is
a. more than one allotropic form of a compound.
b. more than one ionic form of a compound.
c. more than one way to draw a compound’s Lewis structure.
d. more than one isotopic form of an element.
e. more than one electronegativity in the molecule.
13. Which of the following is a resonance structure of the chlorite ClO2- ion?
14.Vinegar is a solution of acetic acid (C2 H4 O2 ) and water. Which of the following is the Lewis structure for acetic
acid?
Chemistry 105: General Chemistry I
Dr. Gutow and Dr. Matsuno
Page 5
Exam 3 Form A
Spring 2004
15. What is the formal charge of the nitrogen atom in hydrogen cyanide (HCN)?
a. 1
b. 0.
c. -1
d. 5
e. -2
16. On the basis of formal charge, which of the following possible resonance structures of the perchlorate ion (ClO4 -)
is most stable?
17. Indicate which type of molecular orbital results from a buildup of electron density between two nuclei.
a. σ
b. π
c. σ*
d. π*
e. δ
18. Which one of the below correctly arranges the bond lengths between two atoms from longest (left) to shortest
(right)?
a. C-C, C=C, C=C
b. N=N, N=N, N-N
c. O-O, O=O
d. C=O, C-O
e. Cl=O, Cl-O
Chemistry 105: General Chemistry I
Dr. Gutow and Dr. Matsuno
Page 6
Exam 3 Form A
Spring 2004
19. Which of the following molecules is paramagnetic? (Hint: you may use the figure attached on the back)
a. Be2
b. C2
c. N2
d. B2
e. F2
Questions Below Here Are For Chapter 7
20. Which of the following cannot absorb infrared radiation
a. HCl
b. SiH4
c. N2
d. C6 H6
e. NO2
21.Increased emission of CO2 due to fossil-fuel consumption has been predicted to lead to a 1.0º-3.5º C rise in Earths
surface temperature during the twenty-first century. Which of the following might offset such global warming?
a. increased emission of methane (CH4 ) from cows
b. increased cloud formation due to the increased evaporation of water
c. increased clear-cutting of old-growth forests
d. decreased growth of phytoplankton in the oceans
e. increased production of CO2 by burning more fossil fuel.
22.Objects warmed by absorbing visible radiation from the Sun emit radiation in the __________ region of the
spectrum.
a. ultraviolet
b. visible
c. infrared
d. microwave
e. gamma ray
23. Infrared spectra usually measure the __________ of radiation by vibrational modes in molecules.
a. emission
b. scattering
c. diffraction
d. absorption
e. reflection
24. Which of the C to O bonds in the following molecules do you expect to absorb the longest wavelength infrared
radiation?
a. the C–O bond in CH3 OH (methanol)
b. there is no way to tell.
c. C≡O
d. the C=O bond in CO2
e. the C=O bond in H2 CO (formaldehyde)
Chemistry 105: General Chemistry I
Dr. Gutow and Dr. Matsuno
Exam 3 Form A
Spring 2004
Page 7
25. How many valence electrons are there surrounding the iodine atom in the iodate ion (IO3 -)?
a. 8
b. 10
c. 5
d. 4
e. 6
26. Which of the following atoms can have an expanded octet?
a. H
b. C
c. N
d. B
e. Se
27. ClO is an important intermediate in the decomposition of stratospheric ozone. What is the proper Lewis structure
for this molecule? Useful information: Electronegativities Cl = 3.0, O = 3.5.
a. Cl – O
b. Cl – O
c. Cl – O
d. Cl – O
e. Cl – O
28. Using the MO diagram (valence orbitals only) for ClO shown below determine the actual bond order for the ClO
molecule.
Cl
ClO
O
∗
σp
3p
E
σp
π∗
π
2p
σ∗
3s
a. 1.5
b. 2.0
2s
σ
d. 3.0
c. 2.5
e. 3.5
29. Based on the MO diagram below and the fact that nuclei with odd numbers of protons like N cause a triple splitting
in ESR (electron spin resonance spectra), what will be observed if you take an ESR spectrum of ClO?
Cl
ClO
O
∗
σp
3p
E
σp
π∗
π
2p
σ∗
3s
2s
σ
a. a single peak
b. a double peak
30. Molecular geometry is determined by
a. electron-proton attractive forces.
b. electron-electron attractive forces.
c. nuclear attractive forces.
d. electron-electron repulsive forces.
e. nuclear repulsive forces.
c. a triple peak
d. a broad peak
e. no peak
Chemistry 105: General Chemistry I
Dr. Gutow and Dr. Matsuno
Page 8
Exam 3 Form A
Spring 2004
31. Which of the following is a square planar molecule? In the molecules below the central atom underlined.
a. NH3
b. PCl5
c. KrF4
d. CH3 COOH
e. SO3 232. Determine the molecular geometry of CF2 Cl2 .
a. linear
b. bent
c. trigonal bipyramidal
d. tetrahedral
e. square planer
33. Which of the following molecules has the smallest H–A–H bond angle, where A represents the central atom? In
the molecules below the central atom is underlined.
a. SiH4
b. H2 S
c. H2 CO
d. CH3 OH
e. BH3
34. Which of the following molecules is expected to be square pyramidal?
a. NH4 +
b. PCl5
c. PCl4 O (P is the central atom)
d. [AlCl4 O]3- (Al is the central atom)
e. XeF5 +
35. Which of the following molecules has a carbon atom that is sp3 hybridized?
a. C2 H2
b. H2 CO
c. CH3 Cl
d. C2 H4
e. H2 CS
36. Which of the following has a central atom with the same hybridization as the oxygen in water?
a. SO2
b. OCS
c. CS2
d. NH3
e. XeF2
Chemistry 105: General Chemistry I
Dr. Gutow and Dr. Matsuno
Page 9
Exam 3 Form A
Spring 2004
37. What is the hybridization of the central iodine in I3 -?
a. sp
b. sp2
c. sp3
d. sp3 d
e. sp3 d2
38. What type of hybridization will lead to a "T-shaped" molecule?
a. sp3 d2
b. sp3 d
c. sp3
d. sp2
e. sp
39. Which of the following diagrams shows the correct orientation of the dipole moment of COCl2 ?
a.
d.
b.
c.
e. none of these
40.What is the partial charge in fractions of an electron on the Br atom in HBr if the dipole moment is 0.78 D and the
bond length is 2.67 pm? Useful constants: 1 D = 3.336 x 10-30 C•m, charge on electron e = 1.60 x 10-19 C.
a. 1. 6 x 101 e
b. 9.7 x 10-21 C
c. 2.9 x 109 D/m
d. 1.8 x 102 8 e
e. 0.061 e