2002.10.28 Analytical Chemistry
1.Differentiate between
(a)accuracy and precision (b)random and systematic error
(c)population mean and sample mean (d)transfer pipet and measuring pipet
(8%)
2.State three essential attributes of a lab notebook.
(3%)
3.State when standard additions and internal standards, instead of a
calibration curve, are desirable, and why.
(6%)
4.The standard deviation in measuring the diameter d of a sphere is ±0.02cm.
What is the standard deviation in the calculated volumn V of the sphere if
d=2.15cm?
(5%)
5.The analysis of a calcite sample yielded CaO percentages of 55.95, 56.00,
56.04, 56.08 and 56.23. The last value appears anomalous, should it be
retained or rejected?
(6%)
6.A method for the analysis of codeine in prescription drugs yielded the
following results when applied to a codeine free blank: 0.1, -0.2, 0.3, 0.2,
0.0, -0.1 mg codeine. Calculate the detection limit (in terms of milligrams
of codeine) at the 90% confidence level, based upon the mean of
(a)two analyses (b)six analyses.
(Hint:The minimum detectable quantity, Δxmin=x1-xb>tsb√(N1+N2)/(N1N2))
(16%)
7.(A)Describe how to analyze a solution of NaI by using the Volhard titration.
(B)Describe the Fajans titration of chloride?
(12%)
8.A reliable assay of ATP in a certain type of cell gives a value of
111.0μmol/100ml, with a standard deviation of 2.8 in four replicate
measurements. You have developed a new assay, which gave the follwing value
in replicate analyses:117, 119, 111, 115, 120, 128μmol/100ml.
(a)Find the mean and standard deviation of your new analysis.
(b)Can you be 95% confident that your method produces a result different
from the "reliable" value?
(15%)
9.How is control chart used? What are three indications that a process is
going out of control?
(8%)
10.Calculate the solubility of silver chloride in 0.01M potassium nitrate. The
thermodynamic solubility constant of silver chloride is 1.8*10^(-10).
(10%)
11.A common procedure for protein determination is the dye-binding assay of
Bradford. In this method, a dye binds to the protein and, as a consequence,
the color of the dye changes from brown to blue. The intensity of blue
color (measured by absorbance of light at a wavelength of 595nm) is
proportional to the amount of protein present.
Protein(mg):0.00, 9.36, 18.72, 28.08, 37.44
Absorbance at 595nm:0.466, 0.676, 0.883, 1.086, 1.280
(a)Detenmine the equation of the least-squares straight line through these
points in the form y=[m(±Sm)]x+[b(±Sb)] with a reasonable number of
significant figures.
(b)Make a graph showing the experimental data and the calculated straight
line.
(c)An unknown protein sample gave an absorbance of 0.973. Calculate the
number of micrograms of protein in the unknown and estimate its
uncertainty with the method.
(Sxx=Σ(xi-x(bar))^2 Syy=Σ(yi-y(bar))^2 Sxy=Σ(xi-x(bar))(yi-y(bar))
m=Sxy/Sxx b=y(bar)-mx(bar) Sr=√(Syy-m^2*Sxx)/(N-2)
Sm=√(Sr^2)/Sxx Sb=Sr√(Σxi^2)/((NΣxi^2)-(Σxi)^2)
Sc=(Sr/m)√(1/M)+(1/N)+((yc(bar)-y(bar))^2)/Sxx*m^2) )
(20%)
另給Values of Studene's t和Values of Q for rejection of data
Total:109%
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作者: abacada (高傲的自信) 看板: NTU-Exam
標題: 91學年度第1學期劉春櫻分析第二次期中考
時間: Wed Jan 29 02:14:25 2003
2002.12. 9
1.Explain the following terms:
(a)salt bridge (b)junctional potential
(c)buffer capacity (d)leveling effect
(e)isoionic point and isoelectric point(with the enzyme ribonuclease as an
example)
(18%)
2.(a)Give the methods to determine the amount of boric acid and borax,
respectively.
(b)Why is it not practical to titrate an acid or bade that is too weak or
too dilute?
(5%)
3.What's the function of desferrioxamine B in the chelation therapy of
Thalassemia?
(4%)
4.Describe the displacement method in EDTA titration for the Ca2+
determination with EBT as indicator, and give the reason to state why a
direct titration method is not used.
(4%)
5.(a)Describe how pH can be measured with a glass electrode?
(b)Why does a dry electrode require several hours of soaking before it
responds to H+ correctly?
(12%)
6.Describe how the Gran plot can be used to find the end point.
(10%)
7.Consider the following simultaneous equilibria:
FeG+ + G- ←→FeG2 (aq) K2=3.2*10^3
G- + H2O ←→HG + OH- Kb=6.0*10^-5
Where G is the amino acid glycine, +H3NCH2CO2(下標)-. Suppose that
0.0500mol of FeG2 is dissolved in 1.00L.
(a)Write the charge balance.
(b)Write two independent mass balance.
(c)Using activity coefficients, find [FeG+] if the pH is fixed at 8.50 and
the ionic strength is 0.10M. For FeG+, use γ=0.79; and for G-, use
γ=0.78.
(12%)
8.Could you derive an equation showing the isoelectric pH for the amphiprotic
compound, glycine, NH2CH2COOH.
(12%)
9.What is the composition by considering the equilibrium that is established
when a piece of copper is immersed in a dilute solution of silver nitrate,
(2Ag+ + 2e ←→ 2Ag (s) E0 =+0.799V; Cu2+ + 2e ←→ Cu (s) E0 =+0.337V)
(12%)
10.The cell voltage of the following galvanic cell is +0.331V.
S.H.E.//Hg(EDTA)2- (0.00500M),EDTA (0.0150M)/Hg(l) ,where the solution
contains Hg2+ and EDTA was buffered to pH 6.00. Find the value of the
formation constant for Hg(EDTA)2- .
(Hg2+ + 2e ←→ 2Hg (l) E0 =0.852V;
for EDTA, pK1=0.0, pK2=1.5, pK3=2.0 and pK4=2.66)
Total:109%
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作者: abacada (高傲的自信) 看板: NTU-Exam
標題: 91學年度第1學期劉春櫻分析期末考
時間: Wed Jan 29 02:35:40 2003
2003. 1.13
I.Explain the following terms:
a)supporting electrolyte b)Faradiac current
c)differential pulse polarography d)square wave polarography
(12%)
II.Problems.
1.Please illustrate a polarogram for showing the following terms and give a
brief description for each term.
a)half-wave potential b)diffusion current
c)limiting current d)residual current
(10%)
2.Describe the component of the C)2 gas sensing electrode, and how the glass
electrode can be used to monitor the concentration of CO2 in aqueous
solution?
(10%)
3.How to determine the concentration of silver nitrate with the direct
potentiometry by coupling of Ag indicator electrode versus a saturated
calomel reference electrode?
(8%)
4.How to determine the concertration of chloride ion with potentiometric
titration by coupling of Ag indicator electrode versus a saturated calomel
reference electrode?
(8%)
5.Give an exanple of the liquid membrane electrode.
(6%)
6.What's meaning for the statement "Bad things can happen in a two-electrode
cell"?
(8%)
7.Give an example of the use of mediators and enzyme (glucose oxidase)
electrode for glucose monitoring in the blood of diabetic patients.
(8%)
8.a)What are the advantages of dropping mercury electrode in polarography?
b)What are the advantages of using a microelectrode for voltammetric
measurements?
(8%)
9.Describe three ways that solute can get to electrode.
(3%)
10.What's the stripping analysis? And why is stripping voltammetry the mose
sensitive of all the polarographic techniques?
(8%)
11.Explain how the specific proteins (prostate-specific antigen in human
blood) can be measured by the amperometric method (in the presence of the
following materials: nylon membrane, gold, thioctic acid, antibody, and
enzyme-antibody conjugate)?
(10%)
12.Describe how to determine the residual water in purified solvents, food
stuffs or polymers with Karl Fischer titration.
(10%)
Total:106%