課程名稱︰普通化學丙
課程性質︰必修
課程教師︰彭旭明
開課學院：醫學院
開課系所︰醫學系
考試時間︰95/11/22
是否需發放獎勵金：Y
（如未明確表示，則不予發放）
試題 :
1.Suppose that 0.473g of an unknown gas that occupies 200.0mL at 1.81 atm
and 25℃ was analyzed and found to contain 0.414g of nitrogen and 0.0591g
of hydrogen.
a) What is the molecular formula of the compound? b) Draw the Lewis
structure of the molecule. c) If ammonia effuses through a small opening
in a glass apparatus at the rate of 3.5x10^-4 mol in 15.0 min at 200.0℃
,how much of the compound will effuse through the same opening in 25.0 min
at 200.0℃?(R:0.08206 L．atm．K^-1．mol, N:14.01, H:1.00)(8%)
2.A bottle contains1.0 mol He(g) and a second bottle contains 1.0 mol Ar(g)
at the same temperature. At that temperature, the root mean square speed
of He is 1477m．s^-1 and that of Ar is 467m．s^-1. What is the ratio of
the number of He atoms in the first bottle to the number of Ar atoms in
the second bottle having these speeds? Assume that both gases behave
ideally.(Atomic weight: He:4.00,Ar:40.0)(6%)
Maxwell distribution of speeds: f(v)=4π*(M/2πRT)^3/2*V^2*e*-Mv^2/2RT
3.The density of a pure gaseous compound was measured at 0.00℃ as a
function of pressure to give the following results:(gas constant R:0.08206
L．atm．K^-1．mol^-1)(8%)
Density(g/L) Pressure(atm)
——————————————
0.17893 0.2500
0.35808 0.5000
0.53745 0.7500
0.71707 1.000
——————————————
Calculate the molar mass of this compound, corrcted for any nonideal
behavior of the gas.
4.(1) Suggest,giving reasons, which substance in each of the following pairs
is likely to have the higher normal melting point(Lewis structure may help
your arguments): a) HCl or NaCl;b)C2H5OC2H5(diethyl ether) or C4H9OH
(butanol);c)CHI3 or CHF3;d)H2O or CH3OH
(2)suggest, giving reasons,which substance in each of the following pairs
is likely to have the higher normal boiling point: a)H2S or H2O;b)NH3 or
PH3;c)KBr orCH3Br;d)CH4 or SiH4 (8%)
5.A unit cell of one of the new high-temperature superconductors is shown
below. a) What is its formula? b) What is the crystal system? c) Give the
fractional coordinates of Cu ions in the unit cell. (8%)
a
圖為3個立方體組合而成 ↑ b
最外面4個頂點為Y ∣ ↗
中間4個頂點為Ba ∣↗
Cu在每個面的面心上(包括接觸面) ↘
O在每個立方體的體心上 ↘
c
6.Iron corrodes in the presence of oxygen to form rust,which for simplicity
can be taken to be iron(Ⅲ) oxide. If a cubic block of iron of side 1.5
cm reacts 15.5 L of oxygen, what is the maximum mass of iron(Ⅲ) oxide
that can be produced? Iron metal has a bcc structure, and the atomic
radius of iron is 124 pm. The reaction takes place at 298K and 1.00 atm.
(Atomic weight: Fe:55.8)(6%)
7.A commonly occuring mineral has a cubic unit cell in which the metal
cations, M, occupy the corners and face centers. Inside the unit cell,
anions, A, occupy all the tetrahedral hole created by the cations. What
is the empiricalformula of the MmAa compound and give the fractional
coordinates of anions in the unit cell? (4%)
8.Could electrons be used for diffraction studies of molecules? The energy
of an electron accelerated through a potential difference V (in volts) is
eV. What potential differences is needed to accelerate electrons from rest
so that they have a wavelength of 100 pm?
Hint: Use the de Brogile relation and the fact that acceleation of an
electron to an energy eV gives it a kinetic energy of 1/2 Me v2. (Planck's
constant h: 6.626x10^-34 J‧s, mass of electron: 9.11x10^-31 kg, charge of
an electron: 1.6x10^-19 C)(6%)
9.Give the statements of the three Laws of thermodynamics. (9%)
10.Calculate the work for each of the following processes beginning with a
gas sample in a piston assembly with T = 305 K, P = 1.79 atm, and V =
4.29 L : a) irreversible expansion against a constant external pressure
of 1.00 atm to a final volume of 6.52 L; b) isothemal, reversible
expansion to a final volume of 6.52 L. (All work must express in J)(6%)
11.The ABC cereal company is developing a new type of breakfast cereal to
compete with a rival product that they call Brand X. You are asked to
compare the energy content of the two cereals to see if the new ABC
product is lower in calories; so you burn 1.00-g samples of the cereals
in oxygen in a calorimeter with a heat capacity of 600.0 J‧℃^-1. When
the Brand X cereal sample burned, the temperature rose from 30.2 K to
309.0 K. When the ABC ceral sample burned, the temperature rose from
299.0 K to 307.5 K. a) What is the heat output of each sample? b) One
serving of each cereal is 30.0 g. How would you label the packages of the
two cereals to indicate the fuel value per 30.0-g serving in joules? In
nutritional Calories (kilocalories)? (6%)
12.Robert Curl, Richard Smalley, and Harold Kroto were awarded the Nobel
prize in chemistry in 1996 for their discovery of the soccer-ball-shaped
molecule C60(碳六十). This fundamental molecule was the first of a new
series of molecular allotropes of carbon. The enthalpy of combustion of
C60 is -25937 kJ‧mol^-1, and its enthalpy of sublimation is +233kJ‧mol^-1
. There are 90 bonds in C60, of which 60 are single bonds and 30 are
double bonds. Like benzene, C60 has a set of multiple bonds for which
resonance structures may be drawn. a) Determine the enthalpy of formation
of C60 from its enthalpy of combustion. b)Calculate the expected enthalpy
of formation of C60 from bond enthalpies, assuming the bonds to be
isolated double and single bonds. c) Is C60 more or less stable than
predicted on the basis of the isolated-bond model? d) Quantify the answer
to part c) by dividing the difference between the enthalpy of formation
calculated from the combustion data and that obtained from the bond
enthalpy calculation by 60 to obtain a per carbon value. e) How does the
number in part d) compare with the per carbon resonance stabilization
energy of benzene(the total resonance stabilization energy of benzene is
approximately 150kJ‧mol^-1)? f) Why might these values differ? The
enthalpy of atomization of C(gr) is +717kJ‧mol^-1. The bond enthalpies
of double bond and single bond of carbon are 612 and 348 kJ‧mol^-1
respectively,enthalpy of formation of carbon dioxide is -393.51kJ‧mol^-1)
(10%)
13.Maleic acid and fumaric acid are cis and trans isomers, respectively,
with the chemical formula C4H4O4. Both are important raw materials for
the chemical industry. a) Calculate the enthalpy of cis-trans
isomerization. b) Which isomer has the lowest standard enthalpy of
formation? c) In the combustion reactions for these compounds, is ΔUc or
ΔHc less negative? ΔHc(maleic acid)= -1355.2kJ‧mol^-1 and ΔHc(fumaric
acid)= -1334.7kJ‧mol^-1. (enthalpies of formation of carbon dioxide and
water are -393.51 and -285.83kJ‧mol^-1 respectively)(6%)
HOOC COOH HOOC H
\ / \ /
C＝C C＝C
/ \ / \
H H H COOH
Maleic acid Fumaric acid
14.Assuming statistical disorder, would you expect a crystal of octahedral
cis-MX2Y4 to have the same, higher, or lower residual entropy than the
corresponding trans isomer? Explain your conclusion.
Y Y
Y | X Y | X
\|/ \|/
M M
/|\ /|\
Y | X X | Y
Y Y
cis-MX2Y4 trans-MX2Y4
15.Potassium nitrate dissolves readily in water, and its enthalpy of
solution is +34.9kJ‧mol^-1. a) Does the enthalpy of solution favor the
dissolving process? b) Is the entropy change of the system likely to be
positive or negative when the salt dissolves? c) Is the entropy change of
the system primarily a result of changes in positional disorders or
thermal disorder? d) Is the entropy change of the surroundings primarily
a result of changes in positional disorder or thermal disorder? e) What
is the driving force for the dissolution of KNO3? (5%)
16.Coupled reactions are used in organisms to drive important biochemical
process. Individual chemical reactions may be added together to form a
net reaction, and the overall reaction free reaction is the sum of the
individual reaction free energies. For examle, ATP is the primary
molecule that stores and releases energy to drive vital nonspontaneous
chemical reactions in our bodies. However, the generation of ATP from
ADP is nonspontaneous and must itself be coupled to a spontaneous
reaction. This process is called oxidative phosphorylation and the
reaction are:
(1)ADP3-(aq) +HPO4 2-(aq)+ H+(aq)→ATP4-(aq) +H2O(l) ΔG=+30.5kJ
(2)NADH(aq)→NAD+(aq)+ H+(aq)+ 2e- ΔG=-158.2kJ
(3)1/2O2(g)+ 2H+(aq)+ 2e-→H2O(l) ΔG=-61.9kJ
(The reaction free energies are for pH=7 but otherwise standard conditions
.) How many molecules of ATP could be formed if all the free energy
released in the oxidation of three molecules of NADH were used to generate
ATP? (6%)
17.Three isomeric alkenes have the formula C4H8(see the following table). a)
Draw Lewis structures of these compounds. b) Calculate ΔG,ΔH,ΔS(標準狀
況下) for the three reactions that interconvert each pair of compounds.
c) Which isomer is the most stable? d) Rank the isomer in order of
decreasing Sm(標準狀況下). (9%)
┌────────┬───────┬───────┐
│ Compound │ ΔHf(kJ/mol) │ ΔGf(kJ/mol) │
├────────┼───────┼───────┤
│2-methylpropene │ -16.90 │ +58.07 │
├────────┼───────┼───────┤
│ cis-2-butene │ -6.99 │ +65.86 │
├────────┼───────┼───────┤
│ trans-2-butene │ -11.17 │ +62.97 │
└────────┴───────┴───────┘
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