Chemistry 123: Physical and Organic Chemistry
Practice Exam 2
2009
The exam will be composed of 3 sections. The first section will contain ~30
multiple choice marked at 1 point each. The second section will consist of
~6 questions of ~4 points each for ~24 points. The third section will
consist of ~ 8 questions of ~ 6 points each.
Section 1: Multiple Choice: (30 marks total) No samples provided,
see quizzes and midterms for examples.
Section 2: Short Answer (28 marks total)
2.1) Name the following 4 compounds: [1 point each, 4 total]
O
H3 C
CH3
N
OH
O
CH3
_______________
________________
O
Cl
Cl
Cl
Cl
Br
F
Cl
CH3
O
_______________
________________
2.2) Draw the following compounds in the box provided [1 point each, 4 total]
a) para-dichlorobenzene
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Chemistry 123: Physical and Organic Chemistry
Practice Exam 2
2009
b) hexane-2,3-dione
c) but-1-en-3-yne
d) (1E)-1-chloro-2-methylbut-1-ene
2.3a) Indicate which of the following would react faster with HCl via a SN1
reaction and justify your answer! [2 Marks]
2-iodo-2-methylpropane compared to 2-bromo-2-methylpropane
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Chemistry 123: Physical and Organic Chemistry
Practice Exam 2
2009
2.3b Indicate which of the following would react faster with CH3OH via a SN2
reaction and justify your answer! [2 Marks]
Br
compared to
CH3
CH3
Br
H3C
CH3
2.4) Consider Electrophilic addition of H2O to each of the the following isomers.
For each indicate the most probable product. [6 Marks]
Cl
H
H
H
H
H
H
Cl
H
H
H
H
H
Cl
H
H
H
H
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Chemistry 123: Physical and Organic Chemistry
Practice Exam 2
2009
2.5) For the compounds below indicate it’s conjugate acid or base and calculate
the appropriate Ka or Kb for that conjugate acid or base. [4 marks]
Acid or base
H2S
K
pK
Conjugate
-7
Ka = 1.0 x 10
3.13
NH2NH2
C6H7O7-
Kb = 8.5 x 10-7
Kb = 4.2 x 10-4
CH3NH3+
2.6a) Fill in the missing values in the following table; [4 marks]
Name
ΔHfº (kJ/mol)
CH3OH (g)
-162.0
CH3OH (l)
-238.7
(CH3)2CO (g)
-216.6
C2H2 (g)
ΔG fº (kJ/mol)
ΔS fº (J/mol)
129.8
-166.3
213.3
209.2
-58.7
2.6b) Based on values in the table presented in 2.6a, how much heat would be
required to vaporize 1 mole of Methanol? [2 marks]
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Chemistry 123: Physical and Organic Chemistry
Practice Exam 2
2009
Section 3: Long Problems (42 marks total)
3.1a) If 2 g of copper shot at 600ºC is added to an isolated dewar containing 100
mL of water at 20ºC. What would the temperature of the system be at equilibrium
if the heat capacity of the dewar can be ignored and the system is completely
isolated. (Specific heat copper is 0.385 J /g ºC) [4 marks]
3.1b) If the water was at 100 ºC, how much water would be vaporized by 2 g of
copper initially at 600 ºC. [2 marks]
3.1c) If 2 g of copper shot and 100 mL of water are in an isolated dewar at 10ºC.
How much energy would need to be removed in order to cool the system to -5ºC.
Assume that the heat capacity of the dewar can be ignored and the system is
completely isolated. (Specific heat copper is 0.385 J /g ºC) [3 marks]
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Chemistry 123: Physical and Organic Chemistry
Practice Exam 2
2009
3.2) If the ΔGº for the following reaction is 36.28 kJ/mol, what is the pH, pOH and
concentration of the H2CO3 at equilibrium if 10 g of H2CO3 is added to 200 mL of
water?
H2CO3 + H2O ↔ HCO3- + H3O+
[6 marks]
3.3) How many grams KCHO2 would need to be added to a 500 mL solution of
2.5 M HCHO2 (Ka= 1.8 x 10-4) to make a buffer of pH 3.2 [4 marks]
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Chemistry 123: Physical and Organic Chemistry
Practice Exam 2
2009
3.4a) If 0.1 g of Silver Nitrite (AgNO2 ; Ksp = 6.0 x 10 -4) is added to 100 mL of
water, what would the pH and pOH be? Note: The Ka for HNO2 is 7.2 x 10-4.
[4 marks]
3.4b) If 0.1 g of Silver Nitrite is added to 0.1 M solution of NaOH, what would the
pH be? How much Silver Nitrite would dissolve?
[2 marks]
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Chemistry 123: Physical and Organic Chemistry
Practice Exam 2
2009
3.5) For the hypothetical reaction A → Products; Sketch the expected graph for
the situations presented below: [4 marks]
a) Reaction is first order
b) Reaction is second order
3.5c) If the value of k can be calculated using on graphs above (ie., as the slope
or the intercept) indicate which one and how. [2 marks]
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Chemistry 123: Physical and Organic Chemistry
Practice Exam 2
2009
3.6) What could be conveniently plotted to enable the calculation of the Activation
Energy (Ea) and the Arrhenius constant (A). Clearly indicate how each of these
values could be determined from the plot. [4 marks]
O
OH
3.7)Aspirin has the structure formula. At body temperature (37°C), O
Ka for aspirin equal 3 x 10-5. If two aspirin tablets, each having a
mass of 325 mg, are dissolved in a full stomach whose volume is
1 L and whose pH is 2, what percent of the aspirin is in the form of
neutral molecules? [3 marks]
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O
CH3
Chemistry 123: Physical and Organic Chemistry
Practice Exam 2
2009
3.8) Determine the ΔHº for reaction #1 given the information provided; [4 marks]
Reaction 1) CH4 (g) + ½ O2 (g) → CO2 (g) + H2 (g)
ΔHº = ______________
Reaction 2) CH4 (g) + 2 O2 (g) → CO2 (g) + 2H2O (g)
ΔHº = -802 kJ
Reaction 3) CH4 (g) + CO2 (g) → 2CO (g) + 2H2 (g)
ΔHº = +247 kJ
Reaction 4) CH4 (g) + H2O (g) → 2CO (g) + 3 H2 (g)
ΔHº = +206kJ
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