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Chemistry 123: Physical and Organic Chemistry Midterm 2 March
13, 2009
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Name: ______________________ Student ID#: ________________ 1)
The optical rotation of plane-polarized light of the reactant
molecule
presented below is +121.1°. Show the reaction products and
indicate the net optical rotation of the products in the SN1
reaction presented below?
2) Indicate the relationship between the two molecules presented
below and indicate which is more stable and why.
/50 Total Marks
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Chemistry 123: Physical and Organic Chemistry Midterm 2 March
13, 2009
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3) If the ratio of Carbon-14 to Carbon-12 in a living tree is
1.3 x 10-12, what will this ratio be in 2000 years if the half life
(t) of Carbon 14 is 5730 years? What is the rate (k) of the
carbon-14 decay? . 4) If a “Van Hoff plot” is generated for a
reaction and a linear regression of this plot indicates a “best
fit” line of Y= 9273.5X – 14.6 Calculate the values for ΔH and ΔS.
If the temperature if set to 30°C, would the reaction be
spontaneous? Support your assertion by calculating the value for
ΔG.
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Chemistry 123: Physical and Organic Chemistry Midterm 2 March
13, 2009
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5) Consider a beaker containing 18 mL of water initially at 20°C
that is cooled to to -10°C. Describe each step of the process and
calculate the amount of energy that would need to flow in or out of
the system. At each step indicate if the entropy is increasing or
decreasing and under what conditions the reaction would be
spontaneous. 6) Concisely state the 3 laws of Thermodynamics
preferably using formula’s.
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Chemistry 123: Physical and Organic Chemistry Midterm 2 March
13, 2009
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7) If the ΔG° for the reaction below is -33.3 kJ/mol and the
initial partial pressures of each of the gasses is given below the
equation, calculate the ΔG for the reaction at 50°C. Is it
spontaneous? What is the equilibrium constant for this
reaction?
N2(g) + 3 H2(g) ↔ 2NH3(g) 1.0 atm 3.0 atm 0.5 atm 8) ΔfH° of NH3
is -80.29 kJ/mol, determine ΔS° for the reaction presented in
question 7.
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Chemistry 123: Physical and Organic Chemistry Midterm 2 March
13, 2009
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Multiple Choice (circle best answer) 8) Which best describes
this chemical structure? A) Primary amine B) tertiary amine C)
Secondary amine D) none of these 9) For the chemical structure
presented in question 8, which best describes the carbon connected
to the NH2 group. A) Primary carbon B) tertiary carbon C) Secondary
carbon D) none of these . 10) For the chemical structure presented
in question 8, How many secondary hydrogen atoms are there? A) 9 B)
0 C) 2 D) 4 11) Which of the following correctly names the chemical
structure presented in question 8? A) 2-methylbutan-2-amine B)
Dimethyl-propanamine C) Tert-butamine D) 2,methyl-2,amine butane
12) What of the following is most reactive in an SN1 reaction? A)
Primary alkyl halide B) tertiary alkyl halide C) Secondary alkyl
halide D) not enough information to determine . 13) For graphite
which would be numerically larger? (A) ΔfG° (B) ΔfH° (C) ΔS°
14) Which of the following would have the greater ΔS? (A) C(s)
(B) C(g) (C) CO(g) (D) CO2(g) 15) If a reaction has a half-life of
one day and it is initiated on Monday, how much remains on Friday?
(A) ~20% (B) ~5% (C) ~3% (D) ~12% 16) For the reaction, N2(g) + 3
H2(g) ↔ 2NH3(g) , the rate would be; A) First order B) Second order
with regard to [NH3] C) Third order D) not enough information to
determine
/11 (1 point each)
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Chemistry 123: Physical and Organic Chemistry Midterm 2 March
13, 2009
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17) CO2 is a greenhouse gas because…. (A) It absorbs infrared
radiation (B) It has a high entropy (C) It makes plants grow better
in a greenhouse (D) It has a high enthalpy of formation 18) Carbon
dating is possible due to; (A) open minded rate laws (B)
Irradiation of N2(g) by cosmic radiation (C) Naturally occurring
Carbon isotopes (D) radioactivity from nuclear bombs
