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CHEM 167 EXAM 3 REVIEW
Supplemental Instruction
Iowa State University
Leader:
Course:
Instructor:
Date:
Sean and Ugerah
CHEM 167
Dr. Bonarccossi and Dr. Meyer
13th November, 2016
1. For the following molecules, describe which intermolecular forces are present and rank
them in order of increasing strength.
a. C4H10
b. Br-I
c. CH4
d. F-Cl
e. CH3NH2
2. Which of the following statements about the allotropes of carbon is false?
a. In diamond, the carbon atoms are bonded together in a three-dimensional
tetrahedral lattice.
b. Graphite has similar properties to diamond because they are both made of only
carbon atoms.
c. Diamond is very hard and inert because of strong covalent bonds holding all the
atoms together.
d. In graphite, carbon atoms are bonded together in two-dimensional planes.
e. Graphite is soft because only weak forces hold the planes of C atoms together.
3. Which of the following statements about intermolecular forces and liquid properties is
false?
a. The hydrogen bonding force is the strongest intermolecular force.
b. Stronger intermolecular forces cause a higher boiling point in the liquid state.
c. Stronger intermolecular forces cause a higher vapor pressure in the liquid state.
d. Water has a high surface tension because of its strong intermolecular forces.
e. Gasoline is more volatile than water.
4.Which drawing represents a
molecule?
bonding molecular orbital for a homonuclear diatomic
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5.Which of the following would be a p-type doping for As?
a. S
b. Al
c. Ga
d. (b) and (c)
e. (a) and (b)
6.Which of the following polymers is an example of a block copolymer
f. ABABBBABBABBAB
g. ABABABABABABA
h. AAABBBAAABBB
i. BABABABABABABA
j. None of the above
7.Nickel crystallizes in a face-centered cubic lattice. If the density of the metal is 8.908
g/cm3, what is the unit cell edge length in cm?
8.A piece of copper metal of mass 6.22 kg is heated from 20.5 °C to 324.3 °C. Calculate the
heat absorbed by the metal. Specific heat is 0.386J/g °C.
9. If 3.4 kJ of heat flows out of the system while 4.8 kJ of work is done by the system on the
surroundings, what is the internal energy?
10. Given the following reactions,
2 S(s) + 3 O2 (g)  2 SO3(g)
S(s) + O2(g)  SO2 (g)
ΔH = -790 kJ
ΔH = -297 kJ
What is ΔH° for the reaction 2 SO2(g) + O2(g)  2 SO3(g)?
11.Draw lewis structures for the following molecules. Give the shape of the molecule,
hybridization of the central atom, polarity, and the bond angle(s).
a. CH2F2
b. OF2
c. PO33-
d. BCl3
e. BeF2
f. PBr5
12.Given the following electronegativities, which covalent bond is the most polar?
Element
Electronegativity
a.
b.
c.
d.
e.
C-H
N-H
O-H
O-C
O-N
H
2.1
C
2.5
N
3.0
O
3.5
13. A 0.500 g sample of naphthalene (C10H8) is burned in a bomb calorimeter containing 650
grams of water at an initial temperature of 20.00ºC. After the reaction, the final temperature of
the water is 26.4ºC. The heat capacity of the calorimeter is 420 J/ºC. Using these data, calculate
the heat of combustion of naphthalene in kJ/mol.
14. Determine the final temperature when 10.0 g of aluminum at 130.0 °C mixes with 200.0
grams of water at 25.0 °C. The specific heat of aluminum is 0.901 J/g °C. (Coffee cup
calorimeter problem.)
15. Find the ΔH°rxn for C2H6(g) + 7/2 O2(g)  2 CO2(g) + 3 H2O(g)
ΔH°f C2H6(g) = -84.7 kJ/mol
ΔH°f CO2(g) = -393.5 kJ/mol
ΔH°f H2O(g) = -241.8 kJ/mol
16.For Phosphorous, ____ is an example of p doping and ____ is an example of n doping.
a) Sulfur / Silicon
b) Carbon / Selenium
c) Silicon / Sulfur
d) Oxygen / Boron
17. Without doing a calculation, predict whether the entropy change will be positive or
negative when each of the following reactions occurs in the direction it is written
a.
b.
18. Which of the following statements about energy is true?
a. The change in energy of the system + the change in energy of the surroundings
for an exothermic reaction is negative
b. A substance that goes from a solid to a gas has a positive work term.
c. The enthalpy for a reaction in a bomb calorimeter is equal to the change in heat
(q).
d. The most efficient electricity conversion is electricalthermal.
19. How much heat must be removed to change 75.0 grams of water at 25.0 °C to ice at -35.0
°C? ΔH°fusion ice = 333.55 J/g; specific heat of ice = 2.03 J/g °C
20. Considering the definition ΔG=ΔH-TΔS, match the following possible combination of
ΔH and ΔS (in terms of negative or positive signs).
ΔH
+
-
ΔS
+ _____
- _____
+ _____
a) Always spontaneous at all temperatures
b) only spontaneous at low temperatures
c) Only spontaneous at high temperatures.
21. Calculate ΔG° at 45°C for the reaction for which ΔH° = -86.6 kJ and ΔS° = -382 J/K.
22. Determine whether each of the following statements is true or false. If false, modify the
statement to make it true.
a. An exothermic reaction is always spontaneous.
b. When ΔG° is positive, the reaction cannot occur under any conditions.
c. ΔS° is positive of a reaction in which there is an increase in the number of moles.
d. If ΔH° and ΔS° are both negative, ΔG° will always be negative.
22.Spontaneous process
a) Never occur in nature
b) Always have a negative delta S
c) Always have a positive Delta H
d) Are quick
e) Do not need continuous intervention
23.The atmosphere around the earth is warmed because _____
a. Warm air cannot escape, as in a greenhouse
b. Molecules in the atmosphere are warmed by radiation from the earth that retain
heat
c. Fossil fuels release heat
d Plants absorb CO2
e. Plants release CO2