Name:__________________ Student number:_______________________
I. 單選題（每題 2 分）
1) The rate for a particular reaction is k[A][B]2. If the initial concentration of B
increases from 0.1 M to 0.3 M, by which factor does the initial rate increase?
a) 2 b) 6 c) 12
d) 3 e) 9
2) At a particular temperature, cyclopropane undergoes a first-order isomerization
reaction to form propylene. The first-order rate constant is 0.10 s-1. The initial
concentration of cyclopropane is 1.0 M. What is the concentration of propylene
after 10 s?
a) 0.37 M
b) 0.50 M
c) 0.63 M
d)
0.12 M
e) 1.0 M
3) Which statement is true?
a) When two opposing processes proceed at identical rates, the system is at
equilibrium.
b) Catalysts shift the position of an equilibrium.
c) The concentration of the products equals that of the reactants and both are
constant at equilibrium.
d) An endothermic reaction shifts toward reactants when heat is applied.
e) None of the above
4) For the reaction A(g) + B(g)  C(g) + D(g), the gases A, B, C, and D are at
equilibrium. If gas A is introduced, the value of K
a) increases because by adding A, more products are made and the product to
reactant ratio increases.
b) decreases because A is a reactant so the product to reactant ratio decreases.
c) does not change because A does not affect the product to reactant ratio.
d) does not change as long as the temperature is constant.
e) depends on whether the reaction is endothermic or exothermic.
5)
a)
b)
c)
d)
e)
In deciding which of two acids is the stronger, one must know
the concentration of each acid solution.
the pH of each acid solution.
the equilibrium constant of each acid.
all of the above
both a and c must be known
1
6) How much water should be added to 10.0 mL of 12.0 M HCl so that it has the
same pH as 0.90 M acetic acid? (Ka = 1.8 x 10-5).
a) 30 mL
7)
a)
b) 300 mL
c) 3 L
d) 30 L
e) 300 L
The pKa of HOCl is 7.5. Calculate the pH of a 0.5 M solution of HOCl.
7.5
b) 6.5
c) 3.9
d) 10.1
e) 0.3
8) Calculate the pH of a solution prepared by mixing 50 mL of a 0.10 M solution of
HF with 25 mL of a 0.20 M solution of NaF. pKa of HF is 3.14.
a)
3.14
b) 10.80
c)
5.83
d)
7.35
e) 12.00
9) Suppose 0.010 mol HNO3 is added to 500. mL of a solution that is 0.10 M in
aqueous ammonia and 0.20 M in ammonium nitrate. The volume does not change.
What is the pH of the resulting solution? The Kb for NH3 = 1.8 x 10-5.
a) 8.00
b) 8.95
c) 5.05
d) 8.82
e) 2.00
10) A student used 16.60 mL of 0.100 M NaOH to titrate a 0.2000-g sample of an
unknown acid. Which of the following acids would the unknown most probably be?
Assume that only the hydrogens bonded to oxygen are titrated by the sodium
hydroxide, and that, because of experimental error, the student's value may not be
identical with the theoretical value.
a) succinic acid, HOOCCH2CH2COOH, molar mass 118
b) benzoic acid, C6H5COOH, molar mass 122
c) phthalic acid, C6H4(COOH)2, molar mass 166
d) oxalic acid, HOOCCOOH, molar mass 90.
e) not enough information
11) Which of the following is true?
a) As long as the disorder of the surroundings is increasing, a process will be
spontaneous.
b) For any process, Ssurr and Ssys have opposite signs.
c) If Ssurr = -Ssys, the process is at equilibrium.
d) Ho is zero for a chemical reaction at constant temperature.
e) none of these
2
12) Choose the correct statement.
a) Exothermic reactions are always spontaneous.
b) Free energy is independent of temperature.
c) A reaction that exhibits a negative value of S cannot be spontaneous.
d) At constant pressure and temperature, a decrease in free energy ensures an
increase in the entropy of the system.
e) none of these
13) For the reaction A + B  C + D, Ho = +40 kJ and So = +50 J/K. Therefore,
the reaction under standard conditions is
a) spontaneous at temperatures less than 10 K.
b) spontaneous at temperatures greater than 800 K.
c) spontaneous only at temperatures between 10 K and 800 K.
d) spontaneous at all temperatures.
e) not spontaneous at any temperature.
14) At 699 K, Go = -23.25 kJ for the reaction H2(g) + I2(g)  2HI(g). Calculate
G for this reaction if the reagents are both supplied at 10.0 atm and the product is at
1.00 atm.
a) -3.5 kJ
b) -36.6 kJ
c) +36.6 kJ
d) -50.0 kJ
e) +50.0 kJ
15) Assume that the enthalpy of fusion for ice is 6020 J/mol and does not vary
appreciably over the temperature range 270 K-290 K. If one mole of ice at 0℃ is
melted by heat supplied from surroundings at 280 K, what is the entropy change in the
surroundings in J/K?
a) +22.0
b) +21.5
c)
0.0
d) -21.5
e) -22.0
II. 計算問答題（必須寫出計算過程）
1)
At 2200℃, Kp = 0.050 for the reaction N2(g) + O2(g)  2NO(g)
What is the partial pressure of NO in equilibrium with N2 and O2 that were
placed in a flask at initial pressure of 0.80 and 0.20 atm, respectively. (5pts)
Ans:
N2(g)
+ O2(g)
Initial
0.80
0.20
Final
0.80-x
0.20-x
Kp = 0.050 = (2x)2/[(0.80-x)(0.20-x)]
0.05x2 – 0.05x + 8.0 x 10-3 = 4x2

2NO(g)
0
2x
3
3.95x2 + 0.05x - 8.0 x 10-3 = 0
∴ x = 3.9 x 10-2 atm or –5.2 x 10-2 atm (does not make sense)
∴ PNO = 2 x 3.9 x 10-2 = 7.8 x 10-2 atm
2)
For the following reaction at a certain temperature
H2(g) + F2(g)  2HF(g)
it is found that the equilibrium concentration in a
5.00-L rigid container are [H2] = 0.0500 M, [F2] = 0.0100 M, and [HF] = 0.400
M. If 0.200 mol of F2 is added to this equilibrium mixture, calculate the
concentrations of all gases once equilibrium is reestablished. (6 pts)
Ans:
K = (0.400)2/(0.0500)(0.0100) = 320
H2(g)
+
F2(g)
Initial
0.0500
Final
0.0500-x
K = 320 = (0.400+2x)2/(0.0500-x)2


2HF(g)
0.0500
0.400
0.0500-x
0.400+2x
17.9 = (0.400+2x)/(0.0500-x)
 x = 0.0249 M
∴ [HF] = 0.400 + 2 x 0.0249 = 0.450 M
[H2] = [F2] = 0.0500 – 0.0249 = 0.0251 M
3)
Calculate the pH of a 0.20 M C2H5NH2 solution (Kb = 5.6 x 10-4). (5 pts)
Ans:
Initial
C2H5NH2 +
0.20
H2O

C2H5NH3+ +
0
OH~0
Final
0.20-x
x
Kb = 5.6 x 10-4 = x2/(0.20-x) ≒ x2/0.20 (assuming that x << 0.20)
 x = 1.1 x 10-2
(∵ 1.1 x 10-2/0.20 = 5.5 % > 5.0 % rule)
∴ the assumption x << 0.20 is not valid.
x
5.6 x 10-4 = x2/(0.20-x)  x2 + 5.6 x 10-4x – 1.2 x 10-4 = 0
x ≒ 1.0 x 10-2 = [OH-] ∴ [H+] = 1.0 x 10-12  pH = 12
4)
Sodium azide (NaN3) is sometimes added to water to kill bacteria. Calculate the
concentration of all species in a 0.010 M solution of NaN3. The Ka value for
hydrazoic acid (HN3) is 1.9 x 10-5.
(6 pts)
Ans:
N3
+
H2O 
HN3 +
0.010
0
0.010-x
x
Kb = Kw/Ka = 1.0 x 10-14/1.9 x 10-5 = 5.3 x 10-10
5.3 x 10-10 = x2/(0.010-x) ≒ x2/0.010
OH~0
x
 x = [OH-] = 2.3 x 10-6 M
[H+] = 4.3 x 10-9 M
[HN3] = 2.3 x 10-6 M
[N3-] = 0.010 - 2.3 x 10-6 ≒ 0.010 M
4
5)
Quinine (C20H24N2O2) is an important alkaloid derived from cinchona bark. It is
used as an antimalarial drug. For quinine pKb1 = 5.1 and pKb2 = 9.7. One gram of
quinine will dissolve in 1900.0 mL of water. Calculate the pH of a saturated
aqueous solution of quinine. (5 pts)
molar mass of quinine = 324.41 1 g quinine is 1/324.41 = 1.6 x 10-3 M
Q
+
H2O

QH+ +
OH1.6 x 10-3
0
~0
-3
1.6 x 10 -x
x
x
pKb1 = 5.1  Kb1 = 8 x 10-6
Kb2 can be neglected.
-6
2
-3
2
8 x 10 = x /(1.6 x 10 -x) ≒ x /1.6 x 10-3  x = [OH-] = 1 x 10-4 M
Ans:
∴ pH = 10
6)
Calculate the concentrations of Ag+, Ag(S2O3)-, and Ag(S2O3)23- in a solution
prepared by mixing 150.0 mL of 1.00 x 10-3 M AgNO3 with 200 mL of 5.00 M
Na2S2O3. The stepwise formation equilibria are
Ag+ + S2O32-  Ag(S2O3)K1 = 7.4 x 108
Ag(S2O3)- + S2O32-  Ag(S2O3)23-
K2 = 3.9 x 104
(6 pts)
Ans: Since the formation constants are large and S2O32- is in excess, almost all Ag+
becomes Ag(S2O3)23-.
[Ag+]o = (150 x 1.00 x 10-3)/(150+200) = 4.29 x 10-4 M
[S2O32-]o = (200 x 5.00)/(150+200) = 2.86 M
Ag+ +
2S2O32
Ag(S2O3)23Initial
4.29 x 10-4
2.86
0
-4
Final
~0
2.86-2x4.29 x 10
4.29 x 10-4
Final
~0
~2.86
2∴ [S2O3 ] = 2.86 M
∴ [Ag(S2O3)23-] = 4.29 x 10-4 M
4.29 x 10-4
K2 = 3.9 x 104 = [Ag(S2O3)23-]/[Ag(S2O3)-][S2O32-] = (4.29 x 10-4)/[Ag(S2O3)-](2.86)
∴ [Ag(S2O3)-] = 3.8 x 10-9 M
K1 = 7.4 x 108 = [Ag(S2O3)-]/[Ag+][S2O32-] = (3.8 x 10-9)/[Ag+](2.86)
∴ [Ag+] = 1.8 x 10-18 M
5
7)
Calculate the pH of each of the following buffered solutions.
For acetic acid, Ka = 1.8 x 10-5.
(8 pts)
(a) 0.10 M acetic acid/0.25 M sodium acetate.
(b) 0.25 M acetic acid/0.10 M sodium acetate.
(c) 0.080 M acetic acid/0.20 M sodium acetate.
(d) 0.20 M acetic acid/0.080 M sodium acetate.
Ans:
Henderson-Hasselbalch equation can be used to solve the problems.
pH = pKa + log([base]/[acid])
where pKa = -log(1.8 x 10-5) = 4.74
(a) pH = 4.74 + log(0.25/0.10) = 5.14
(b) pH = 4.74 + log(0.10/0.25) = 4.34
(c) pH = 4.74 + log(0.20/0.080) = 5.14
(d) pH = 4.74 + log(0.080/0.20) = 4.34
8)
AgCl  Ag+ + ClAg+ + NH3  Ag(NH3)+
Ksp = 1.6 x 10-10
K1 = 2.1 x 103
Ag(NH3)+ + NH3  Ag(NH3)2+
K2 = 8.2 x103
Calculate the solubility of AgCl in a 10.0 M NH3 solution.
(6 pts)
Ans:
AgCl(s) +
2NH3(aq) 
Ag(NH3)2+(aq) +
Initial
10
0
Final
10-2x
x
+
2
K = [Ag(NH3)2 ][Cl ]/[NH3] = Ksp x K1 x K2 = 2.8 x 10-3
2.8 x 10-3 = x2/(10-2x)2  x/(10-2x) = (2.8 x 10-3)1/2
∴ x = 0.48 mol/L (solubility of AgCl(s) in 10.0 M NH3 solution)
Cl-(aq)
0
x
6
9)
Consider the autoionization of water at 25oC:
H2O(l)  H+(aq) + OH-(aq)
Kw = 1.00 x 10-14
(a) Calculate Go for this process at 25oC.
R = 8.3145 J/K.mol
(b) At 40oC, Kw = 2.92 x 10-14. Calculate Go at 40oC.
(6 pts)
Ans:
(a) Go = -RT ln K = -8.3145 x 298 x ln(1.00 x 10-14) = 79.9 kJ/mol
(b) Go = -RT ln K = -8.3145 x 313 x ln(2.92 x 10-14) = 81.1 kJ/mol
10) Given the data in Appendix 4, shown below, calculate Ho, So and K (at 298K)
for the synthesis of ammonia by the Haber process:
(10 pts)
N2(g) + 3H2(g)  2NH3(g)
Hfo (kJ/mol)
o
.
S (J/K mol)
N2(g)
H2(g)
NH3(g)
0
0
-46
192
131
193
Also calculate G for this reaction under the following conditions.
(a) T = 298K, PN2 = PH2 = 200 atm, PNH3 = 50 atm.
(b) T = 298K, PN2 = 200 atm, PH2 = 600 atm, PNH3 = 200 atm.
Ans:
Ho = 2 x (-46) = -92 kJ
So = 2 x (193) –192 – 3 x (131) = -199 J/K
Go = Ho – TSo = -92 – 298 x (-199)/1000 = -33 kJ
K = exp(-Go/RT) = exp(33000/(8.3145x298)) = 6.1 x 105
(a) G = Go + RT ln Q = -33 + ((8.3145 x 298)/1000) ln[(50)2/(200)(200)3]
∴ G = -33 –33 = -66 kJ
(b) G = Go + RT ln Q = -33 + ((8.3145 x 298)/1000) ln[(200)2/(200)(600)3]
∴ G = -33 –34.4 = -67 kJ
7
解釋名詞（每題 4 分）
1)
second law of thermodynamics
In a spontaneous process, there is always an increase in the entropy of university.
2)
third law of thermodynamics
The entropy of a perfect crystal at 0 K is zero.
3)
state function
A property that is independent of pathway.
4)
amphoteric
A substance that can behave either as an acid or as a base is amphoteric.
5)
Write the form of Arrhenius equation.
k = A e-Ea/RT
8