Chem 200 Exam 3B Spring 2006
Name______________________________________________
All questions are worth 4 points.
For the molecules and ions given below:
a. Draw the Lewis structure
b. Predict (name) the geometry of the molecule.
c. State which hybrid orbitals would be expected for the central atom.
d. Give the approximate bond angle for the central atom.
1) NH4+
2) KrF2
3) PCl3
4) CO32-
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MULTIPLE CHOICE. CIRCLE the one alternative that best completes the statement or answers the
question.
5) Of the following, which gives the correct order for atomic radius for Mg, Na, P, Si and Ar?
A) Si > P > Ar > Na > Mg
B) Na > Mg > Si > P > Ar
C) Mg > Na > P > Si > Ar
D) Ar > Si > P > Na > Mg
E) Ar > P > Si > Mg > Na
6) Which one of the following compounds would produce an acidic solution when dissolved in water?
A) CO2
B) SrO
C) CaO
D) Na2O
E) MgO
7) The hybridization of the carbon atom labeled x in the molecule below is __________.
B) sp2
A) sp
C) sp3
D) sp3 d
8) Which equation correctly represents the first ionization of aluminum?
A) Al- (g)
Al (g) + e-
B) Al (g)
Al+ (g) + e-
C) Al (g)
Al- (g) + e-
D) Al (g) + eE) Al+ (g) + e-
Al- (g)
Al (g)
9) What is the electron configuration for the Co2+ ion?
A) [Ar]4s03d7
B) [Ne]3s2 3p10
C) [Ar]4s23d9
D) [Ar]4s23d5
E) [Ar]4s13d6
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E) sp3 d2
10) There is/are __________
A) 0
bond(s) in the molecule below.
B) 1
C) 2
D) 4
E) 16
D) 4
E) 3
11) How many equivalent resonance forms can be drawn for CO3 2-?
A) 2
B) 0
C) 1
12) Given the electronegativities below, which covalent single bond is most polar?
Element:
Electronegativity:
H
2.1
A) N-H
C
2.5
N
3.0
B) O-H
O
3.5
C) C-H
D) O-C
E) O-N
13) The chloride of which of the following metals should have the greatest lattice energy?
A) cesium
B) potassium
C) sodium
D) rubidium
E) lithium
14) The bond angles marked a, b, and c in the molecule below are about __________, __________, and
__________, respectively.
A) 109.5°, 109.5°, 90°
B) 120°, 109.5°, 120°
C) 109.5°, 109.5°, 120°
D) 109.5°, 109.5°, 109.5°
E) 90°, 180°, 90°
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15) Three monosulfur fluorides are observed: SF2, SF4 , and SF6 . Of these, __________ is/are polar.
A) SF2 only
B) SF4 only
C) SF6 only
D) SF2 , SF4 , and SF6
E) SF2 and SF4 only
16) Which of the following substances, is / are capable of forming hydrogen bonds?
CH3OH
NH3
H2 S
H2 O
HCl
A) NH3 only
B) H2 O and NH3
C) all are capable of forming hydrogen bonds
D) CH3OH, NH3 and H2O
E) H2 O only
17) Of the following substances, only __________ has London dispersion forces as its only intermolecular force.
A) HCl
B) CH3OH
C) CH4
D) NH3
E) H2 S
18) A mixture of carbon dioxide and an unknown gas was allowed to effuse from a container. The carbon
dioxide took 1.25 times as long to escape as the unknown gas. Which one could be the unknown gas?
A) SO2
B) HCl
C) CO
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D) H2
E) Cl2
19) The heating curve shown was generated by measuring the heat flow and temperature of a solid as it was
heated. The heat flow into the sample in the segment __________ will yield the value of the Hvap of this
substance.
A) AB
B) CD
C) EF
D) BC
E) DE
CALCULATIONS: Show your setup and circle your final answer. Rember to include units and correct sig
fig where appropriate.
20) The formal charge on nitrogen in NO3- is __________.
21) The rms speed of methane (CH4) molecules at 25.0 °C is __________ m/sec.
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22) The density of nitric oxide (NO) gas at 1.37 atm and 44.1 °C is __________ g/L.
23) The molar mass of a gas is __________ g/mol if 4.5 g of the gas occupies 2.1 L at STP.
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24) Calcium hydride (CaH2) reacts with water to form hydrogen gas:
CaH2 (s) + 2H2O (l)
Ca(OH)2 (aq) + 2H2 (g)
How many grams of CaH2 are needed to generate 32.0 L of H2 gas at a pressure of 0.800 atm and a
temperature of 37 °C?
25) A gas mixture of Ne and Ar has a total pressure of 4.00 atm and contains 16.0 mol of gas. If the partial
pressure of Ne is 2.75 atm, how many moles of Ar are in the mixture?
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