Chem 360 March Quiz, 2004
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1. When running GC, what parameter is most important in controlling retention times?
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2. When running HPLC, what parameter is most important in controlling retention times?
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3. In GC, what are the disadvantages of using too low a temperature?
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4. In GC, what are the disadvantages of using too high a temperature?
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5. In GC, what are the disadvantages of using too low a flow?
In terms of the resulting chromatogram:
AND the reason in terms of Rate-kinetic theory:
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6. In GC, what are the disadvantages of using too high a flow?
In terms of the resulting chromatogram:
AND the reason in terms of Rate-kinetic theory:
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7. State the van Deemter equation.
What factors control mass transfer in the stationary phase?
What factors control longitudinal diffusion?
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8. What column parameters can be optimized for HPLC?
For each parameter, do you want it big or small or? .
Give a typical value for each.
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9.What are the advantages and disadvantages of using a gradient?
Think about both GC and HPLC.
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10.Why is an interface necessary between a chromatograph and a mass spectrometer?
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11.Describe one interface used between HPLC and MS.
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12.What information can be obtained by using MS as a chromatography detector?
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13. If a cell is at equilibrium, what is the cell voltage?
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14. Distinguish between a reversible electrochemical cell and an irreversible
electrochemical cell.
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15. Indicate whether the following cell would act as an anode or cathode when coupled
with a standard hydrogen electrode in a galvanic cell.
Ag ‫ ׀‬AgI (sat’d), KI(0.0922 M)
AgI + e-
Ag(s) + I-
Eo = -0.151 V
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16.What is a junction potential?
Draw a diagram showing how it arises.
Why do we want to minimize it?
How can we minimize it?