Practice Exam I
Dr. Overway
CHEM 162-01,02
February 2009
Here are some things you may need.
Formal Charge = # of valence e - - # of non-bonding e - - # of bonds
Formal Charge = # of valence e - - # of non-bonding e - - ½ (# of bonding e - )
R= 8.3145 J/(K mol)
R=0.08206 (Latm)/(Kmol)
Thermodynamic data:
Species
Hof
(kJ/mol)
C2H4 (g)
52.4
CH4 (g)
-74.6
H2O (g)
-241.8
SO2 (g)
-296.8
H2O (l)
-285.8
H2 (g)
0.0
C3H6 (g)
20.0
NH3 (g)
-45.9
C3H3N (l)
172.9
O2 (g)
0.0
SO3 (g)
-396.0
Psolv = Xsolv Posolv
Kb (water) = 0.512 C kg/mol
Kf (water) = 1.858 C kg/mol
T = Kf cm ·i
T = Kb cm ·i
= MRT·I
Grxn = (n*Gof prod) - (n*Gof react)
Horxn = (n*Hof prod) - (n*Hof react)
Sorxn = (n*Sof prod) - (n*Sof react)
Go = Ho- TSo
GT = Ho- TSo
Suniv = Ssys + Ssurr
Species
E=hc/λ
h=6.62610-34 Js
c=2.9979108 m/s
ClO2-(aq)
ClO3-(aq)
O2 (g)
Avagadro’s number = 6.022×1023 things/mol
Sof
(J/K mol)
101
162
205
Gof
Sof
(kJ/mol)
68.4
-50.5
-228.7
-300.1
-237.1
0.0
74.62
-16.4
208.6
0.0
-371.1
(J/K mol)
219.3
186.3
188.8
248.2
69.95
130.68
226.9
192.8
188
205.15
256.8
Species
Gof
KCl(s)
Cl-(aq)
K+(aq)
(kJ/mol)
-408.5
-131.2
-283.3
CHEM 162-01,02
Practice Exam
Name
.
1. Match each of the following terms with the correct definitions.
Answer Term
Definition
polymorph
A a highly ordered solid
allotrope
B a solid substance whose molecules are held together by covalent
bonds
ionic solid
C a solid substance whose molecules are held together by metallic
bonds
network covalent solid D the different crystal structures in which an element can exist
metallic solid
E a crystal structure the containing an atom at each of the corners of
the cube and an atom at each face of the cube
molecular solid
F a solid substance whose molecules are held together by ionic
bonds
crystalline solid
G a substance that has very little order
amorphous solid
H a substance that bursts into flame when in contact with the air
I the different crystal structures in which a compound can exist
J a solid substance whose molecules are held together by H-bonds,
dipole-dipole forces, or dispersion forces
2. In each of the following comparisons, circle the correct compound.
highest boiling point:
CH4
CH3CH2OH
lowest viscosity:
H2O
CH3CH2CH3
highest vapor pressure at 25 C:
PH3
NH3
highest boiling point:
H2S
H2O
lowest freezing point:
SF6
CH3CH2CH2CH2CH3
3. Determine whether each of the following statements are true (T) or false
(F) concerning the two phase diagrams shown below.
Substance C is less dense as a liquid than a solid.
At pt. 1 substance D is a supercritical fluid.
Going from pt. 2 to pt. 3 in the phase diagram for substance D involves a
phase change from gas to solid.
At 1 atm of pressure substance D melts and substance C sublimes if the
temperature is increased.
4. Of the intermolecular forces listed in the textbox to the right, which would be the strongest force that
would have to be overcome in order to convert the following molecules from a liquid to a gas?
a. CCl4
______________________________.
A) Ionic
b. HBr
______________________________.
B) Covalent
C) Dispersion
c. H2O
______________________________.
D) Dipolar
d. H2NCH2CH2CH3
______________________________.
E) Metallic
e. CH3CH2CH2CH3
F) Hydrogen bonding
______________________________.
5. Circle the aqueous solution that should have the highest boiling point. Explain your answer.
A.
1.0 M KNO3 (electrolyte)
B.
0.75 M NaCl (electrolyte)
C.
0.75 M CuCl2 (electrolyte)
D.
2.0 M C12H22O11 (sucrose, non-electrolyte)
6. (8 pts) Dimethylglyoxime, DMG, is an organic compound used to test for aqueous nickel(II) ions. A
solution prepared by dissolving 65.0 g of DMG (a non-electrolyte) in 375 g of ethanol boils at
80.3°C. What is the molar mass of DMG? (Kb = 1.22 C /molal, boiling point of pure ethanol =
78.5°C)
7. Lysine is an amino acid that is an essential part of nutrition but which is not synthesized by the
human body. What is the molar mass of lysine if 750.0 mL of a solution containing 8.60 g of lysine
(a non-electrolyte) has an osmotic pressure of 1.918 atm? (T = 25.0°C)
8. Determine Grxn for the following reaction at 25 °C:
2 C3H6 (g) + 2 NH3 (g) + 3 O2 (g)  2 C3H3N (l) + 6 H2O (l)
9. Determine Grxn for the following reaction at 350 °C:
2 C3H6 (g) + 2 NH3 (g) + 3 O2 (g)  2 C3H3N (l) + 6 H2O (l)
10. Draw the band gap structure for 1) an insulator and 2) a conductor. Label all of the parts.
11. Given the data below, calculate the temperature at which the reaction becomes spontaneous.
(Hrxn = -92 kJ and Srxn = -199 J/K). State whether the reaction is spontaneous above or below the
determined temperature.
N2(g) + 3 H2(g) <===> 2 NH3(g)
12. Give a brief description of the 1st Law of Thermodynamics. What does it mean?
13. Entropy is most effectively described by microstates at the microscopic level. Give an example of a
microstate in the case of a coin toss or a roll of dice.