課程名稱︰普通化學甲
課程性質︰
課程教師︰曾文碧
開課系所︰地質 農化 大氣
考試時間︰2005.6.24
試題 :
(1) The electronic transition of benzene-like molecules usually occurs in
the UV region. However, carrots exhibit an orange color. Explain this
phenomenon in terms of electronic spectroscopy and particle-in-a-box model.
[Hint: Energy of a particle-in-a-box with a length L: E = n2h2 / (8mL2)]
[6%]
(2) For a general reaction involving a single reactant, aA R products, that
is nth order in A, the rate law is Rate = -d[A]/dt = k[A]n .
(a) Derive the integrated rate form for the zero-order reaction (n=0) and
specify how would you make a plot to obtain the rate constant k,
(b) Do the same as (a) for the first-order reaction (n=1). (8%)
(3) (a) What are dipole-dipole forces?
(b) How do typical dipole-dipole forces differ from hydrogen bonding
interactions?
(c) In what ways are they (dipole-dipole forces and hydrogen bonding
interactions) similar?
(d) Discribe the relationship between molecular size and the strength
of London dispersion forces? [8%]
(4) Make simple drawings to illustrate (a) tetrahedral and
(b) octahedral holes [4%]
(5) What specific features of chemical substances do we prefer to when we
say that “like dissolves like”? [4%]
(6) Give four typical characteristics of transition metals. [4%]
(7) Define and give an example for each of the following terms: (a) ligand
, (b) chelate, (c) bidentate, (d) complex ion. [8%]
(8) Give formulas for the following: (a) potassium tetrachlorocoboltate(II)
, (b) sodium dicyanobis(oxalato)ferrate(III),
(c) tetracarbonyldihydroxochromium(III) ion,
(d) amminetrichloroplatinate(II) ion. [8%]
(9) Define and give an example for each of the following terms:
(a) coordination isomers, (b) linkage isomers, (c) geometrical isomers,
(d) optical isomers, (e) racemic mixture. [10%]
(10) Predict the number of unpaired electrons in the complex ion
[Cr(CN)6]4?. [4%]
(11) Why the localized electron model is rarely used today? [4%]
(12) Determine the structure for each of the following compounds:
(a) 4-ethyl-3,5-dimethylnonane, (b) 4-tert-butylheptane. [4%]
(13) Draw all the structural isomers for C8H18 that have “pentane” as
the root name (longest carbon chain). [6%]
(14) Give structure for each of the following aromatic hydrocarbons:
(a) m-bromonitrobenzene, (b) 4-chloro-2-phenylhexane, (c) o-ethyltoluene. [6%]
(15) Draw and give the names for all the structural and geometric (cis-trans)
isomers of C3H5Cl. [10%]
(16) Draw and give the names for all isomers of trichlorobenzene. [6%]
詳解:
(1) Pages 683-684. Carrots contain beta-carotene whose molecular structure
has a long conjugated carbon chain attached to a six-member ring. Consider the
particle-in-a-box model for being used in an electronic transition, the
energy (E) is inversely proportional to the square of the length of the
conjugated carbon chain (L). Namely, E μ= 1 / (L2). As L increases, E
decreases. It is then expected that the electronic transition of beta-carotene
may absorb visible photons. The absorption spectrum shows
that beta-carotene indeed absorbs the visible light in the violet and blue region, as seen in Fig. 14.57 (See page 684 of textbook). The rest of the visible light remains unabsorbed. These photons “add up” to give carrots orange color. [6%]
(2) See pages 715-719 for the derivation of the equations.
(a) 0th order, [A] = -kt + [A]0, plot [A] vs. t, slope = -k,
intercept = [A]0
(b) 1st order, ln[A] = -kt + ln[A]0, plot ln[A] vs. t, slope = -k,
intercept = ln[A]0 [8%]
(3) See page 818, Exercise 16.11 [8%]
(4) See page 798, Fig. 16.36. [4%]
(5) See page 858, Exercise 17.27. The nature of interparticle
(intermolecular) forces. Polar solutes and ionic solutes dissolve in polar
solvents and nonpolar solutes dissolve in nonpolar solvents. [4%]
(6) See page 933. (1) More than one oxidation state is often found,
(2) The cations are often complex ions,
(3) Most compounds are colored,
(4) Many compounds are paramagnetic. [4%]
(7) See page 972, example 20.17, and page 944.
(a) ligand: species that donates a pair of electrons to form a covalent bond
to a metal ion, e.g. NH3, (b) chelate: ligand that can form more than one bond
to a metal ion, e.g. ethylenediamine (en), oxalate, (c) bidentate: ligand
that can form two bonds to a metal ion, e.g. ethylenediamine (en), (d) complex
ion: metal ion and ligands, e.g. [Co(NH3)6]3+. [8%]
(8) (a) K2[CoCl4],
(b) Na3[Fe(CN)2(C2O4)2],
(c) [Cr(CO)4(OH)2]+,
(d) [Pt(NH3)Cl3]-. [8%]
(9) (a) coordination isomers, isomers in which the composition of the
complex ion varies, e.g. [Cr(NH3)5SO4]Br and [Cr(NH3)5 Br]SO4,
(b) linkage isomers, isomers in which the composition of the complex
ion is the same, but the point of attachment of at least one of the
ligands differs, e.g. [Co(NH3)4(NO2)Cl]Cl and [Co(NH3)4(ONO)Cl]Cl,
See page 949, Fig. 20.10,
(c) geometrical isomers, or referred to as cis-trans isomers, isomers in
which atoms or groups of atoms can assume different positions around
a rigid ring or bond, e.g. cis-Pt(NH3)2Cl2 and trans-Pt(NH3)2Cl2,
See page 949, Fig. 20.11,
(d) optical isomers, isomers that have opposite effect on plane-polarize
d light, e.g. cis-Co(en)2Cl2+, See page 953, Fig. 20.17(b),
(e) racemic mixture, An equal mixture of the d and l isomersin solution,
does not rotate the plane of polarized light at all because the two
opposite effects cancel. e.g. a mixture containing 50% d-Co(en)33+
and 50% l-Co(en)33+ [10%]
(10) See page 959, example 20.5, two unpaired electrons. [4%]
(11) See page 957, The localized electron model fails to predict important
properties of complex ions, such as magnetism and color. [4%]
(12) See page 1018, example 22.3. [4%]
(13) (a) 2,2,3-trimethylpentane, (b) 2,2,4-trimethylpentane,
(c) 2,3,3-trimethylpentane, (d) 2,3,4-trimethylpentane,
(e) 3-ethyl-2-methylpentane, (f) 3-ethyl-3-methylpentane. [6]
(14) See page 1025, Fig. 22.12 and page 1060, Exercise 20.12. [6%]
(15) (a) cis-1-chloro-1-propene, (b) trans-1-chloro-1-propene,
(c) 2-chloro-1-propene, (d) 3-chloro-1-propene, (e) chlorocyclopropane. [10%].
(16) See page 1061, Exercise 20.27, (a) 1,2,3-trichlorobenzene,
(b) 1,2,4-trichlorobenzene, (c) 1,3,5-trichlorobenzene. [6%]
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