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課程名稱︰普通化學丙
課程性質︰必修
課程教師︰鄭淑芬
開課學院：工
開課系所︰機械系
考試日期（年月日）︰99/05/06
考試時限（分鐘）：2hr
是否需發放獎勵金：是 謝謝
（如未明確表示，則不予發放）
試題：
General Chemistry, 2nd Mid-term Exam
Single Choice Questions (16%; 2 points per question, -0.5 points per
mistake)
1. If the orbitals of two atoms overlap and interact with
constructive interference, the resulting increase in wave
density results in a:
(a) bonding molecular orbital
(b) antibonding molecular orbital
(c) valence band
(d) conduction band
2. "Doping" pure silicon with gallium results in a _____ material.
(a) ionic conductor
(b) n-type semiconductor
(c) p-type semiconductor
(d) semimetal
3. Which of the following substances has the highest boiling point?
(a) C3H6 (b) Ar (c) CH2Cl2 (d) HF
4. Which substance has the lowest vapor pressure:
(a) CH3OCH3 (b) C3H8
(c) CH3CH2OH (d) C3H6
5. Under constant volume conditions, the change in internal energy
equals the:
(a) entropy
(b) insulation capacity
(c) enthalpy
(d) heat flow
6. Calculate ΔS for the reaction: 2N2O(g) → 2N2(g) + O2(g)
S in J/mol K for: N2O(g)=240.0, N2(g)=191.5, O2(g)=205.0
(a) +157 J/K (b) -157 J/K (c) +108 J/K (d) -480 J/K
7. Which of the following compounds having the same structure as
diamond has the largest band gap?
(a) Ge (b) GaAs (c) ZnSe (d) CuBr
8. Consider the combustion of glucose (C6H12O6). This reaction is:
(a) spontaneous at all temperatures
(b) non-spontaneous at all temperatures
(c) spontaneous towards higher temperatures
(d) non-spontaneous towards lower temperatures
Multiple Choice Questions (21%, 3 points per question, -0.5 points
per mistake)
9. Which of the following diatomic molecules is paramagnetic?
(a) B2 (b) C2 (c) N2 (d) O2
10. Which one of the following molecules has a planar geometry?
(a) PCl3 (b) BF3 (c) XeF4 (d) SF4
11. A new alloy is designed for use in a car radiator. If the 17.6kg
radiator required 8.69 x 10^5 J of heat to warm from 22.1℃ to
155.8℃, what is the specific heat of the new alloy?
(a) 0.365 J/g℃ (b) 8.27 J/g℃ (c) 0.00491 J/g℃ (d) 1.70 J/g℃
12. What is the oxidation state of the metal ion which forms a metal
oxide compound that crystallized with metal ions occupying half
of the octahedral holes in a cubic close-packed array of oxide
ions?
(a) 1 (b) 2 (c) 3 (d) 4
13. Freonc12 is used as refrigerant. Its heat of vaporization is
289 J/g. What mass of Freon 12 must evaporate in order to freeze
100 g of water initially at 18℃? (The heat of fusion of water
is 334 J/g; the geat capacity of water per gram is 4.18 J/g K.)
(a) 20.8 g (b) 26.0 g (c) 117 g (d) 142 g
14. From the values given for ΔH0 and ΔS0 at 298 K, which of the
following reactions is spontaneous under standard conditions at
298 K?
(a) N2(g) + 3F2(g) → 2NF3(g) ΔH0 = -249 kJ;ΔS0 = -278 J/K
(b) N2(g) + 3Cl2(g) → 2NCl3(g) ΔH0 = 460 kJ;ΔS0 = -275 J/K
(a) N2F4(g) → 2NF2(g) ΔH0 = 85 kJ;ΔS0 = 198 J/K
(a) 2POCl3(g) → 2PCl3(g) + O2(g) ΔH0 = 572 kJ;ΔS0 = 179 J/K
15. According to the band theory, which of the following provides an
explanation for the electrical conductivity of metals?
(a) A partly filled conduction band
(b) A filled valence band
(c) A valence band overlapping an empty conduction band
(d) A small gap between the valence band and the conduction band
Problems:
16. Write the Lewis structures and give the shapes of each of the
following molecules; predict which substance of each pair has the
higher boiling point with proper explanations: (16%)
(a) PF3 or PF5
(b) CO2 or SO2
(c) XeF2 or IF3
(d) cis-CHCl=CHCl or trans-CHCl=CHCl
17. Briefly explain the following substances. What kinds of structure
or functional groups are required? Give one application for each
of them. (8%)
(a) liquid crystal (b) ionic liquid
18. Calculate the ΔE, ΔH, ΔS, ΔG, q, and w values when expanding
0.165 mol of He gas in 0.500 L at 25℃ against an external
pressure of 2.50 atm isothermally. (10%)
19. (a) Sketch the 3s molecular orbitals for a linear (Na)6 where all
the Na atoms lie on the z axis. Correlate them with the
molecular-orbital energy level diagram. (8%)
(b) Indicate the highest occupied molecular orbital (HOMO) and
the lowest unoccupied molecular orbitals. (2%)
(c) What will be the molecular-orbital energy level diagram if
the Na tomes in (Na)6 are arranged in a hexagon? (8%)
20. (a) Show the molecular-orbital energy-level diagram of BC,
indicating the bonding and anti-bonding orbitals. (5%)
(b) Write the valence-shell electron configuration of BC. (2%)
(c) What are the bond orders of BC, BC+, and BC-, respectively?
Also, put them in the order of increasing bond length. (5%)
(d) Which of the above three species are "paramagnetic"? (3%)
21. Fermentation consistent of conversion of fructose (C6H12O6) to
ethanol (C2H5OH) and CO2.
(a) Is this an exothermic or endothermic process?
(b) If you want to keep the fermentation process at a constant
temperature, how much water is required for each liter of
alcohol produced? Assume that the water starts at 25.0℃ and
cannot get warmer than 28.5℃. (10%)
(ΔHf of C6H12O6(fructose) = -1265.6 kJ/mol, ΔHf of C2H5OH
= -277.6 kJ/mol, ΔHf of CO2 = -393.5 kJ/mol, specific heat of
water = 1.00 cal/g-K, density of ehtanol is 0.789 g/mL)
22. A reference book lists the following values for carbon
tetrachloride at 298 K. Estimate the normal boiling point of
carbon terachloride. (5%)
─────────────────────────────────
Substance ΔHf0 (kJ/mol) ΔGf0 (kJ/mol) S0 (J/mol-K)
─────────────────────────────────
CCl4(g) -102.9 -60.63 309.7
CCl4(l) -135.4 -65.27 216.2
─────────────────────────────────
Useful informations:
gas constant, R = 0.08206 atm L mol-1 K-1 = 8.314 J mol-1 K-1
Avogadro constant NA = 6.022 x 10^23 /mol
Planck's constant, h = 6.626 x 10^(-34) J s = 6.626 x 10^(-27) erg s
1 L atm = 101.3 J
1 cal = 4.184 joule
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