課程名稱︰物理化學二
課程性質︰必修
課程教師︰吳嘉文
開課學院：工
開課系所︰化工系
考試日期（年月日）︰2009/04/30
考試時限（分鐘）：110
是否需發放獎勵金：是
（如未明確表示，則不予發放）
試題 :
Second Midterm Exam of Physical Chemistry
April 30th, 2009
1. (15%) The resistance of aluminum is 9x10-3 ohm. Assume the current is 1.25
A. (5% for each)
(a) Calculate the potential drop across a piece of aluminum wire that is 2.0
mm in diameter and 1.0 m long.
(b) Calculate the conductance (G) of the aluminum wire described in (a).
(c) Calculate the electrolytic conductivity (κ) of the aluminum wire
described in (a).
2. (40%)
(a) The molar ionic conductivities at infinite dilution are 7.352 x 10-3 (S m2
mol-1) for K+ and 7.634 x 10-3 (S m2 mol-1) for Cl-. Calculate Λο for KCl
from these data. (10%)
(b) Using the Λο value of KCl from (a), and the Λο values for HCl is
4.261 x 10-2 (S m2 mol-1) and for K(CH2ClCOO) is 1.132 x 10-2 (S m2 mol-1).
Calculate the value of the molar conductivity at infinite dilution for
monochloroacetic acid (i.e., CH2ClCOOH). (Hint: monochloroacetic
acid is a weak electrolyte) (10%)
(c) Calculate the Ka for CH2ClCOOH when the concentration of
CH2ClCOOH is 1.323 x 10-3 M. The Λ value at such concentration is
2.46 x 10-2 (S m2 mol-1). (10%)
(d) Explain the Ostwald’s dilution law by using the example in (d). (10%)
3. (25%) A solution of LiCl was electrolyzed in a Hittorf cell. After a
current of 0.9 A had been passed for 2 h, the mass of LiCl in the anode
compartment had decreased by 0.973 g. The mass of LiCl is 42.4 g.
(a) Explain (t+/t-) = (amount lost from anode compartment/amount lost from
cathode compartment) (5%)
(b) Calculate the transport numbers of the Li+ and Cl- ions. (10%)
(c) If Λο(LiCl) is 115 ohm-1 cm2 mol-1, what are the molar ionic
conductivities and the ionic mobilities. (10%)
4. (20%) The solubility product of barium sulfate is 9.2 x 10-11 mol2 dm-6.
Assume the DHLL to apply.
(a) Calculate the solubility in an aqueous solution containing 0.1 M NaNO3
and 0.2 M Zn(NO3)2. (B = 0.51 mol-1/2 dm3/2)(10%)
(b) Is (b) a salting in or salting out effect? (10%)
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