Download Chemistry Final Test

Chemistry
Final Test
June 22, 2007
Total Score: 100 points
Time: 3 hours (18:00-21:00)
You are not allowed to ask TAs questions regarding the content of the test.
However, using non-programmable calculators is allowed.
1、
（12％）Compound A and B are reactants of two simple chemical reactions, rxn. c and
rxn. d, respectively. One of these reaction is first-order, and the other is second-order.
The following data were collected for these two reactions:
rxn. c
time (min)
0
1
2
3
5
7
rxn. d
time (min)
0
1
2
3
4
6
[A] (mM)
200
100
67
50
33
25
[B] (mM)
160
141
80
71
40
20
(a). What kind of reaction has its half life independent of the initial concentration of
the reactant? first- or second-order reaction?
(3%)
(b). Which reaction is a first-order seaction? And determine the half-life (t1/2) of this
reaction.
(3%)
(c). Determine the rate constants (including the units) of these two reactions.
(6%)
2、（9％）The mechanism of the decomposition of ozone is known as:
step 1.
O3 → O2 + O
fast, rate constant k1
reverse reaction: O2 + O → O3
step 2.
fast, rate constant k1’
O3 + O → O2 + O2
slow, rate constant k2
(a). What is the intermediate in this mechanism?
(b). Which step is the rate determing step?
(2%)
(2%)
(c). There are two useful techniques, steady-state approximation and
pre-equilibrium condition, for deriving rate laws according to the reaction
mechanisms. Please use one of them to derive the rate law of the decomposition
of ozone, and explain the key point of the technique you use.
3、（9％）Single choice
1
(5%)
(1)
According to collision theory, which factor below will NOT affect the reaction
rate?
(3%)
c relative mean speed of reactant molecules
d the orientations of colliding molecules
e temperature
f all factors listed above will affect reaction rate
(2)
Arrhenius equation indicates the relationship among rate constant k, temperature,
and activiation energy Ea. Please find out the incorrect description listed below.
(3%)
c lnk is proportional to 1/T and Ea
d a set of Arrhenius parameters can be used to predict the rate constant at
the temperature within the range of the original measurements
e Arrhenius equation can not be applied to aqueous phase reaction
f reactions with higher Ea have rates that depend more strongly on the
temperature
(3) Find out the incorrect description about catalyst listed below.
(3%)
c a catalyst provides an alternative pathway with lower Ea
d the concentration of a homogeneous catalyst will appear in the rate law
e catalysts can be poisoned, or inactivated
f enzymes are catalysts produced by living cells, but they can not be
poisoned
4、(15%) Answer the following short questions. Each question gives you 1%.
(a)
(b)
(c)
(d)
(e)
(f)
(g)
(h)
(i)
(j)
What is the element with largest density?
What is the transition metal with largest possible number of oxidation states?
What is the lanthanide contraction?
Which among the three oxides of chromium—CrO, Cr2O3, and CrO3—is acidic?
What is the name of ligands given by CO32− and H2O?
What does it mean ferrocene?
What does it mean chelate?
Give an example of a pair of coordination isomers.
Give an example of a chiral complex.
Give an example of a pair of enantiomers.
2
(k) Why ligand field splitting is usually smaller for tetrahedral complexes than for
octahedral ones?
(l) Give an example of a weak-field and strong-field ligand.
(m) Why for the octahedral complexes, there exist high- and low-spin states, and for
the tetrahedral ones, only the high-spin states?
(n) What is the complementary color to green?
(o) Many transition metal complexes are very intensively colorful. What are the two
mechanisms responsible for it?
5、(15%) [CoCl2Br2F2]4− forms an octahedral complex.
(a) Draw all possible stereoisomers of this complex. (9%)
(b) Identify all possible pairs of enantiomers. (3%)
(c) Identify all achiral structures. (3%)
6、（40%）單選題，每題 2 分，不倒扣
6-1、Consider the reaction of ethene with bromine water to produce 1,2-dibromoethane.
Which of the following statements is correct regarding this reaction?
(A) This reaction is a nucleophilic reaction.
(B) This reaction is a substitution reaction.
(C) A negatively charged intermediate is involved in this reaction.
(D) A cyclic bromonium ion is an intermediate in this reaction.
6-2、What major product(s) is(are) obtained from the following reaction?
(A)
(B)
(C)
(D)
(E)
1,4-dinitrobenzene
1,2-, 1,3-, and 1,4-dinitrobenzene
1,3-dinitrobenzene
1,2-dinitrobenzene and 1,4-dinitrobenzene
1,2-dinitrobenzene
6-3、How many isomeric dichloromethylbenzenes exist?
(A) four
(B) five
(C) six
(D) seven
3
6-4、For the compounds below, which statement is true?
Cl
Cl
Cl
Cl
1
(A)
(B)
(C)
(D)
2
Compound 1 is chiral.
Compounds 1 and 2 are chiral.
Compounds 1 and 2 are geometric isomers.
Compounds 1 and 2 are identical.
6-5、Which of the following could be a cycloalkane?
(A) C3H8 (B) C5H12 (C) C6H14 (D) C6H12 (E) C4H10
6-6、The formation of an ester is
(A)
(B)
(C)
(D)
(E)
a substitution reaction.
an oxygenation reaction.
an addition reaction.
an irreversible reaction.
a condensation reaction.
6-7、All of the following function as nucleophiles in nucleophilic substitution reactions
except
(A) H2O
(B) CH3CH2O-
( C) SH-
(D) CN-
(E) PH3
6-8、Which of the following is most volatile?
(A) CH3CH(OH)CH2CH3
(C) (CH3)2C(OH)CH3
(E) CH3CH2OCH2CH3
(B) CH3(CH2)3OH
(D) (CH3)3COH
6-9、When aldehydes react with Tollen's reagent,
(A) a red precipitate forms.
(C) a ketone is produced.
(E) an alcohol is produced.
(B) silver ions are produced.
(D) the aldehyde reduces silver ions.
6-10、Which of the following monomers is used to produce Teflon?
(A) CHClCH2
(E) CH(CN)CH2
(B) CF2CF2
(C) CH2CH2
4
(D) CH(CH3)CH2
6-11、 Classify the following molecule:
(A) ether
(B) secondary alcohol
(E) primary alcohol
(C) phenol
(D) tertiary alcohol
6-12、The complimentary nucleic acid sequence for the following DNA sequence—GAC
TAC GTT AGC—is
(A) CTG ATG CAA TCG
(C) CGA TTG CAT CAG
(B) GAC TAC GTT AGC
(D) TCA GCA TGG CTA E) none of these
6-13、Which of the following compounds can exhibit geometrical isomerism?
[A]
[B]
[D]
[E]
[C]
6-14、If you were to heat pentanoic acid and 2-butanol with a strong acid, you would
most likely discover in your flask:
(A) a ketone
(B) an amine
(D) an aldehyde
(E) an ester
(C) an alkane
6-15、The boiling point of methanol is much higher than that of ethane. This is primarily
due to
(A) the difference in molar masses of methanol and ethane.
(B) the carbon oxygen double bond in the methanol.
(C) the hydrogen bonding in methanol.
(D) the significant molecular size difference between methanol and ethane.
(E) none of these.
5
6-16、Which structure represents an optically active aldehyde?
(A)
(B)
(D)
(E)
(C)
6-17、Which of the following monomers are used to produce the polymer:
I.
(A) II and III
II.
(B) III
III.
(C) I
(D) II
(E) I and III
6-18、Which one of the following statements about the structure of proteins is
INCORRECT ?
(A) Hydrogen bonding stabilizes the α-helix proteins.
(B) Heat can disrupt tertiary structure.
(C) Nonpolar groups tend to face the outside of a protein in an aqueous solution.
(D) Ionized amino acid side chains can form salt bridges within a protein.
(E) Disulfide bonds provide strong intrachain interactions.
6-19、Which statement is true?
(A) Each gene in the DNA molecule codes for a specific protein.
(B) Protein synthesis takes place in the cytoplasm of the cell.
(C) Messenger RNA can be found in both the nucleus and the cytoplasm of each
cell.
(D) When a peptide bond is formed, H2O is produced.
(E) all of these
6
6-20、Consider the following four compounds:
Which of the above compounds would have the same physical properties (m.p., b.p.,
density, etc.)?
(A) II and III
(B) I and II
(C) I and III
(D) I and IV
(E) III and IV
7