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Author Question: A chemist wishes to carry out a gravity chromatographic separation using diethyl ether and ethanol ... (Read 52 times)

swpotter12

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on: Aug 23, 2018

A chemist wishes to carry out a gravity chromatographic separation using diethyl ether and
  ethanol as the eluting solvents.
  (a) With which solvent should the chemist begin the elution?
  (b) What would happen if the chemist started with the other solvent?



Question 2

When measuring a refractive index, what should you do if
  (a) no dividing line between light and dark areas can be observed through the eyepiece?
  (b) the dividing line can be seen, but it is fringed with color?



dantucker

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Reply #1 on: Aug 23, 2018
Answer to Question 1

(a) An elution chromatography is always started with the less polar solventdiethyl ether, in
this case.
(b) The more polsr solvent (ethanol) will carry all components through the column with little
or no separation.



Answer to Question 2

(a) Either (1) use the fine or the coarse adjustment control knob on the refractometer, the
knobs that control the refractive index setting of the instrument, or, if (1) does not work, (2)
place more compound on the prism.
(b) Adjust the dispersion correction knob.



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