推 Alankashiwa:是分析化學丙吧 ? 11/15 16:05
課程名稱︰分析化學丁
課程性質︰必修
課程教師︰陳俊顯
開課學院：工學院
開課系所︰化工系
考試日期（年月日）︰ 96/10/31
考試時限（分鐘）：10:20~12:00
是否需發放獎勵金：是
（如未明確表示，則不予發放）
試題 :
1.(22%)definition
(a)describe how isoelectric point is different from isoionic point
(b)write Handerson-Hasselbalch equation and give an exapmle of how to apply
this equation.
(c)Give an example to explain homogeneous precipitation. Is such
precipitation good or bad? Why?
2.(18%)Gravimetric Analysis
(a)How is an inclusion different from an occlusion?
(b)Write an equation to express relative supersaturation. Why is high
supersaturation undesirable in a gravimetric precipitation?
(c)Why are many ionic precipitates washed with electrolyte solution
instead of pure water?
(d)Why is it less desirable to wash AgCl precipitate with aqueous NaNO3 than
with HNO3 solution?
3.(10%)Mass Balance Equation
(a)Write the mass balance for CaF2 in water if the reactions are
CaF2 <--> Ca^2+ + 2F- and F- + H+ <--> HF(aq)
(b)Write a mass balance for CaF2 in water if, in addition to the prceding
reactions, the following reaction take place:HF(aq) + F- <--> HF^2-
4.(30%)EDTA titration. A 100.0-mL solution of the ion M^n+ at a concentation
of 0.0500M buffered to PH 9.00 was titrated with 0.0500M EDTA. The formation
constant of MY^n-4 is 1.00*10^12. Find [M^n+] at the following V(EDTA).
(a)Find the conditional formation constant.(有附表格)
(b)Calcuate the concentration M^n+ at V(EDTA)= 0.50 * V(ep).
(c)Calcuate the concentration M^n+ at V(EDTA)= V(ep).
(d)Calcuate the concentration M^n+ at V(EDTA)= 1.100 * V(ep).
(e)At this pH, some experimental design will use auxiliary complexing agent.
What are the advantage(s) and disadvantage(s) of using such an agent?
(f)(1)Use 4b-4d as an example to illustrate the difference between analytical
concentration and equilibrium concentration. (2)Comment on how the concept
of analytical concentration simplifies the calculation for 4b-4d.
5.(30%)Titration of Diprotic Acid & Bufer Solution. Given that pKas of
carbonic acid (H2CO3) are 6.35 and 10.33. Atitration experiment was carried
out using HCl(aq) as the titrant and the firstend point was found at 10.00ml
(a)Sketch qualitatively the titration out curve. Indicate and describe
features that represent such titration regardless the exact concentration
of the titrant and the volume of the sample.
(note: (1)your grade will be evaluated based on some features of the curve
such as the values at certain pHs.
(2)you don't need C(HCl) nor V(H2CO3) to answer this question.)
(b)Find a reasonable indicator from the Table and justify your choice.
(i.e.,explain why your choice is reasonable.)
(c)In class, we mentioned that it helps to boil the solution a little prior
to the second end point. Please describe under what conditions the
boiling helps in the determination of V(ep) and why it does.
(d)Define buffer capacity by equations and describe how you can find buffer
capacity from your answer of 5a.
(e)If carbonic acid is used to prepare buffer solution, waht pH ranges do
the solutions have reasonable buffer capcaity?
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