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General Chemistry
段考一
98 2nd Semester Quat-Chapters(13~16) Examination I
物一甲, 2009年 4月 1日 (星期 四), 13:10-15:00 S401
成績_132___/132pts(Bonus32pt.)
班級______姓名__TA___
學號_____________
I.Multiple Choice(48分)單選題(每題3分,直接在卷上作答)
1. Under physiological conditions, amino acids in solution carry _______ (p. 508) E
A.no electrical charges.
B.a net positive charge, due to an -NH3+ group or groups.
C.a net negative charge, due to a -COO¯ group or groups.
D.both -NH2 and -COOH groups.
E.both -NH3+ and -COO¯ groups.
2. Consider the expression below, showing the terms which contribute to the heat of solution, ∆Hsoln:
∆Hsoln = ∆Hsolute + ∆Hsolvent + ∆Hmix
Which of the following sets correctly shows the signs (positive or negative) of the three terms on
the right hand side of the equation?
(p. 515) C
A.∆Hsolute > 0; ∆Hsolvent > 0; ∆Hmix > 0
B.∆Hsolute <0; ∆Hsolvent < 0; ∆Hmix < 0
C.∆Hsolute > 0; ∆Hsolvent > 0; ∆Hmix < 0
D.∆Hsolute < 0; ∆Hsolvent < 0; ∆Hmix > 0
E.∆Hsolute < 0; ∆Hsolvent > 0; ∆Hmix < 0
3. A saturated solution of carbon dioxide in water contains 3.00 g of CO2 when the CO2 partial
pressure is 8.0 atm. What mass of CO2 will escape if the partial pressure is lowered to 3.2 atm?
(p. 522) D
A.0.90 g
B.1.20 g
C.1.40 g
D.1.80 g
E.2.20 g
4. A 2.0% (w/v) solution of sodium hydrogen citrate, Na2C6H6O7, which also contains 2.5% (w/v) of
dextrose, C6H12O6, is used as an anticoagulant for blood which is to be used for transfusions.
What is the molarity of the sodium hydrogen citrate in the solution? (p. 526) A
A. 0.085 M
B.0.19 M
C.0.53 M
D.1.2 M
E.1.3 M
5. Which of the following statements about the effective nuclear charge, Zeff, is correct? (p. 554) C
A.Zeff increases with the size of the atom.
B.Zeff decreases across a period and increases down a group.
C.Zeff increases across a period and is relatively constant down a group.
D.Zeff increases as the value of the principal quantum number increases.
E.Zeff is greater for hydrogen than for any other element.
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6. Which of the following will have the highest boiling point? (p. 562) D
A.O2
B.Cl2
C.Br2
D.I2
E.Xe
7. Hydrogen forms metallic (interstitial) hydrides with the d and f transition elements. Which of the
following statements is correct? (p. 567) C
A.These substances have distinct stoichiometric formulas like ionic hydrides.
B.Hydrogen forms bonds with the metals by donating its electron to the valence band of the
metal.
C.Hydrogen molecules and atoms occupy holes within the crystal structure of the metal.
D.These substances are useful catalysts.
E.These hydrides are stabilized by hydrogen bonding forces.
8. Xenon forms several compounds with oxygen and fluorine. It is the most reactive non-radioactive
noble gas because (p.
617) E
A.its large radius allows oxygen and fluorine to bond without being crowded.
B.it has the highest electronegativity of these noble gases.
C.it has the highest electron affinity of these noble gases.
D.its effective nuclear charge is lower than the other noble gases.
E.it has the lowest ionization energy of these noble gases.
9. Select the correct name for the following compound.
A.cis-2,3-dimethyl-4-hexene
(p. 643) D
B.trans-2,3-dimethyl-4-hexene
C.cis-4,5-dimethyl-2-hexene
D.trans-4,5-dimethyl-2-hexene
E.trans-4,5-dimethyl-2-heptene
10. Acetominophen is a widely used and an effective pain reliever. Identify the functional group
circled.
(p. 651) C
A.aldehyde
B. alcohol
C. amide
D. amine
E. carbonyl
11. Each amino acid has two functional groups in common and one of 20 other groups attached to the
-carbon. The two functional groups are (p. 667) A
A.carboxyl and amine.
B.ester and amine.
C.carboxyl and amide.
D.alcohol and amine.
E.carboxyl and peptide.
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12. Identify the products of the reaction between 2-bromopentane and potassium ethoxide.
(p. 652) C
A.
B.
C.
D.
.
E.None of these choices is among the products of the reaction.
13. Consider the general reaction:
5Br¯(aq) + BrO3¯(aq) + 6H+(aq)  3Br2(aq) + 3H2O(aq)
For this reaction, the rate when expressed as [Br2]/t is the same as: (p. 690) D
A.-[H2O]/t
B.3[BrO3¯]/t
C.-5[Br¯]/t
D.-0.6[Br¯]/t
E.None of these choices is correct.
14. Sucrose decomposes to fructose and glucose in acid solution. When ln [sucrose] is plotted vs. time,
a straight line with slope of -0.208 hr¯1 results. What is the rate law for the
reaction? (p. 701) B
A.Rate = 0.208 hr¯1 [sucrose]2
B.Rate = 0.208 hr¯1 [sucrose]
C.Rate = 0.0433 hr [sucrose]2
D.Rate = 0.0433 hr [sucrose]
E.Rate = 0.208 mol L¯1hr¯1 [sucrose]0
15 . The decomposition of dinitrogen pentaoxide has an activation energy of 102 kJ/mol and Hrxn =
+ 55 kJ/mol. What is the activation energy for the reverse reaction?
A.27 kJ/mol
B.47 kJ/mol
C.55 kJ/mol
(p. 709) B
D.102 kJ/mol
E.More information is needed, since this is a Hess's law calculation.
16. The kinetics of the decomposition of dinitrogen pentaoxide is studied at 50C and at 75C. Which
of the following statements concerning the studies is correct? (p. 709) E
A.The rate at 75C will be greater than the rate at 50C because the activation energy will be
lower at 75C than at 50C.
B.The rate at 75C will be greater than the rate at 50C because the activation energy will be
higher at 75C than at 50C.
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C.The rate at 75C will be less than the rate at 50C because the molecules at higher speeds do
not interact as well as those at lower speeds.
D.The rate at 75C will be greater than at 50C because the concentration of a gas increases with
increasing temperature.
E.The rate at 75C will be greater than the rate at 50C because the number of molecules with
enough energy to react increases with increasing temperature.
II. Essay Questions (簡答題 32 分, 每大題 8 分)
1. List five important intermolecular forces that operate in globular proteins, and explain what parts of
the molecule are involved in these forces.(8% ) (p. 509)
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Ans:
1. Ion-dipole forces. These exist between the charged side chains and surrounding water
molecules.
2. Hydrogen bonding. This occurs between polar side chains and the surrounding water molecules.
It is also important in sheet like or helical regions of the protein, occurring between the
C
O group of one peptide bond and the N
H group of another.
3. Disulfide bridges. These form between the side chains of two cysteine residues, and may hold
distant parts of the chain close together.
4. Salt links. These form between oppositely-charged side chains, the charges being due to the COO¯ and -NH3+ groups.
5. Dispersion forces. Nonpolar side chains tend to be located in the nonaqueous interior of the
protein, where they interact with each other by dispersion forces.
Difficulty: H
2. Explain the following 4 terms: (8%)
a. Buckyballs.
b Two allotropes of phosphorous
c. Diagonal relationships
d. The dimeric structure of gaseous aluminum chloride
Ans.
a. Crystals of buckminsterfullerene (C60)
b. White phosphorous (P4) and Red phosphorous
c. : similarities between a Period 2 element and one diagonally down and to the right in
Period 3. It reflects elements＇ similarities in atomic and ionic size
d.
3. Briefly answer the following 4 essay questions: (8%)
a. In one sentence, what is the general requirement for a molecule to be optically active?
b. Draw two different structures with the molecular formula C2H6O.
c. Name the functional group in each structure of the formula C2H6O..
d. Which one of the formula C2H6O will have the higher boiling point, and why?
Ans.
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a. (p. 639) In order to be optically active, the compound must have a non-superimposable mirror
image.
b. (p. 651) a. H3C—CH2—OH and H3C—O—CH3
c. alcohol and ether
d. The alcohol will have the higher boiling point; it will have hydrogen bonding while the ether
does not.
4. You are required to determine the energy of activation (Ea) of a reaction. Briefly describe the
experimental measurements you would make and how you would obtain the activation energy from a
suitable linear plot of the experimental data. (8%)
Ans. (p. 706) Rate constants k over a suitable range of absolute temperatures T.(4%)
A plot of ln k versus 1/T should be linear (2%), and its slope is - Ea/R.(2%)
III. Derivation and Calculation(每大題 8 分, 共 32%)
1 . a. What is the mathematic expression of the Raoult’s Law ? (4%) ,
b. From Raoult’s Law , prove that Vapor Pressure Lowering ΔP = x 2 P1o (4%)
Where (P1o) is the vapor pressure of the pure solvent ; x 2 is the mole fraction of the solute.
Ans.
Raoult＇s Law: The partial pressure of a solvent over a solution (P1) is equal to the
vapor pressure of the pure solvent (P1°) times the mole fraction of the solvent in the
solution (　1).
P1 = x 1P1°
Since x 1 = 1 - x 2 where x 2 is the mole fraction of the solute...
Vapor Pressure Lowering =ΔP= P1° - P1 = x 2 P1o
P1 = (1 - x 2 )P1°
2. Identify by number the main-group of the periodic table (1A-8A) to which the described element (X)
belongs, in each of the following cases. (8%) (Various sections)
a. X commonly forms the ion X2¯.
b. X reacts with water according to the equation
X(s) + 2H2O(l)  X(OH)2(aq) + H2(g)
c. X exists as molecules, X2; its hydride has the formula HX.
d. X is a metal which reacts with oxygen to produce the peroxide, X2O2.
Ans: a. 6A (16)
b. 2A (2)
c. 7A (17)
d. 1A (1)
3.(p.671, Chapt.15 , Figure 15.32 ) Write down the structures of 2-base bounding pairs of the four Ncontaining bases (the pyrimidines: thymine(T) and cytosine(C) and the purines: guanine(G) and
adenine (A) in the forming of double helix of DNA. (8%)
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4. A chemical reaction of the general type A  2B is first-order, with a rate constant of
1.52  10-4 s-1.
a. Calculate the half-life of A. (4%)
b. Assuming the initial concentration of A is 0.067 mol L¯ 1, calculate the time needed for the
concentration to fall to 0.010 mol L¯1. (4%)
Ans: (p. 702) a. t½ = 4.56  103 s;
b. 1.25  104 s
Bonus (20%): Write down any 10 correct chemical structures with names ( each 2 %
points ) of the 20 common amino acids.
Ａ－２. Ｒ基為非極性之中性胺基酸
甘胺酸 Glycine
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丙胺酸 Alanine
白胺酸 Leucine
異白胺酸 Isoleucine
苯胺基丙酸 Phenylalanine
咯啶甲酸 Proline
甲硫丁胺酸 Methionine
胺酸
Valine
色胺酸
Tryptophan
Ｂ－２. Ｒ基為極性之中性胺基酸
絲胺酸 Serine
蘇胺酸 Threonine
半胱胺酸 Cysteine
乾酪胺酸 Tyrosine
天冬素 Asparagine
麩醯胺 Glutamine
Ｃ－２. 鹼性胺基酸
離胺酸 Lysine
魚精胺酸 Arginine
組織胺酸 Histidine
Ｄ－２. 酸性胺基酸
天冬胺酸 Aspartic acid
麩胺酸 Glutamic acid
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