課程名稱︰分析化學一
課程性質︰必帶
課程教師︰林萬寅
開課學院：理學院
開課系所︰化學系
考試日期（年月日）︰2008/01/14
考試時限（分鐘）：120
是否需發放獎勵金：yes
（如未明確表示，則不予發放）
試題 :
1. (10%)
(a) Find the isoelectric point and isoionic point of 0.0020M glutamine acid
(pK1 = 2.19, pK2 = 9.00)
(b) Explain how the isoelectric focusing works.
2. If pK1 = 4.0, pK2 = 8.0, pK3 = 12.0 fpr a triprotic point H3A, answer the
following questions. (20%)
(a) At what pH is [H2A-] = [HA2-]? Explain your answer.
(b) At what pH is [H2A-] = [A3-]? Explain your answer.
(c) What is the principal species at pH = 6.0?
(d) Find the ratios of [HA2-]/[H2A-] and [A3-]/[H3A] at pH = 5.0.
(e) How to prepare 110mL of a buffer solution with pH = 9.0 from the solutions
of 0.010M Na2HA and 0.010M Na3A?
3. The cell SCE||cathodic solution |Cu(s) develops a potential of -0.186V. The
cathodic solution was prepared by mixing 25.0mL of 0.0040M EDTA buffered at
pH = 9.0 with 25.0mL of 0.0400M CuSO4 also buffered at pH 9.0. (Eo = 0.339V
for Cu2+ → Cu(s); reduction potential for SCE is 0.241V; αY4- = 0.054 at
pH 9.0) (20%)
(a) Write the balanced cell reaction.
(b) Find the equilibrium constant for the cell reaction. (Eo = 0.268V for the
calomel eletrode)
(c) Find the concentration of Cu2+in the cathodic solution.
(d) Find the formation constant of Cu(EDTA)2-.
(e) Find the volume of 0.040M EDTA needed to be added to 20mL of 0.0100M CuSO4
to prepared a solution with [Cu2+] = 1.0pM. All solutions are buffered at
pH = 9.0.
4. (10%)
(a) Find the potential for the cell: SCE||cathodic solution|Pt(s). The
cathodic solution was obtained by mixing equal volumes of 0.020M Ce4+ and
0.010M Tl+ in 1M HCl. (Ef for Ce4+/Ce3+ and Tl3+/Tl+ are 1.47V and 0.77V,
respectively)
(b) What will be the cell potential if 0.012M, instead of 0.020M, of Ce4+ was
used to prepared the cathodic solution in (a)?
5. Answer the following questions. (40%)
(a) Explain the meaning of faradic current and charging current.
(b) Draw a typical reversible cyclic voltammogram. Indicate Ipa, Ipc, Epa, Epc
and E1/2 in the figure.
(c) Explain the method of anodic stripping voltammetry.
(d) What is a junction potential? Why is the junction potential of 0.1M HCl|
0.1M KCl of opposite sign and greater magnitude than that of 0.1M NaCl|
0.1M KCl? (mobility: H+ >> K+ > Na+)
(e) Describe the acid error and the alkaline error for a glass electrode.
(f) Explain the principle of operation for a liquid-base ion-selective
electrode.
(g) Explain the phenomena of overpotential and concentration polarization.
(h) Describe how to use a Gran plot to locate the end-point in an acid-base
titration.
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