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Chemistry 360 Final Exam
T. Smith-PalmerApril, 1998
[12] 1.Choose three of the following pairs of compounds.
Fluoride and phosphate
Toluene and xylene
Salicylic acid and phenacetin
Polystyrene(MW=500) and polystyrene (MW 300.000)
Hexyl sulfate and decyl sulfate
For each pair of compounds, suggest a way to simultaneously analyse that pair
of compounds.
SpecifyThe instrument
The column
The detector
The mobile phase
You are not required to describe or explain these.
[12]2.For one of the instruments and its configuration as chosen above, describe the
necessary components of the instrument and its principle of operation for that particular separation.
[15]3.Describe the properties that you would expect to find in an ideal detector for a
chromatographic method. Choose three detectors that are distinctly different (based on completely different principles). Do not use the detector described in the question above.
For each, describe the principle of operation of the detector.
(What does it detect and how does it detect it?)
What instrument is it used in conjunction with?
How does it compare to an ideal detector?
[9]4.The column is the heart of any chromatographic system. What features of a
column are important in determining the efficiency of a separation? How and why do these features affect the separation efficiency. Try and be as specific as possible.
[8]5.Give an equation for four of the following terms. Define the symbols used in
your equation.
Capacity factor
Selectivity factor
Resolution
Height equivalent to a theoretical plate
Column efficiency
[15]6.Describe 5 of the following:
Isotachophoresis
Isoelectric focusing
Positron emission and annihilation
Neutron activation analysis
Ion Cyclotron resonance
Flame Photometric detection
Liquid Scintillation Counting
Solid Scintillation Counting
[5]7.EITHER
A mass spectrometer is a very desirable detector to interface to many chromatographic instruments. Why is this so?
What instruments can be interfaced to mass spectrometers?
Describe an interface that can be used to connect an HPLC to a MS.
[5]OR
What determines whether or not a nucleus is radioactive?
Give an example of a radioactive decay.
Show the changes in the nucleus and note what is ‘given off’.(An equation will suffice).
By using a geiger counter, Billy determined that a plastic disk that he had found at the dump was radioactive. What very simple test could he do to decide whether the disk was emitting beta’s or gamma rays?
[8] 8.Do either (a) or (b).
(a)You are analyzing an unknown which contains only C, H and O.The ir spectrum has indicated that there are no hydroxyl groups in the unknown, but there is one carbonyl group.
The ratio of the 102:103 peak is 50:2.75.
What is the structure of the compound?
Explain how each of the labeled peaks arise.
OR
(b)You are given an unknown. It contains either one or zero nitrogens, in addition to C, H and O.
The 120:121 ratio is 10:0.77.
From the mass spec deduce the structure of the compound, and explain how the labeled peaks arise.
[10]9.Electrolytically generated iodine was used to determine the concentration of H2S in two samples of brackish water. Successive titrations of 50 mL aliquots of Sample A required a constant current of 35.00 mA for 10.22, 10.32 and 10.15 minutes respectively, while times for 100 mL aliquots of Sample B were 0.32, 0.21 and 0.19 minutes respectively. Blanks (100 mL triply deionised water) required a constant current of 35.00 mA for 0.28, 0.29 and 0.38 minutes respectively.
What was the concentration of H2S in Sample A and Sample B?
H2S + I2S(s) + 2I-
F = 9.6485 x 104 C mol-1
[6] 10.Briefly explain 3 of the following:
Pulse Polarography
Anodic Stripping
Limiting Current
Concentration Polarization
Overpotential