(1) Why is it important to avoid air bubbles in the column during chromatography?
(a) the air in the bubbles might react with the compounds being separated
(b) bubbles are toxic and harmful to your health
(c) bubbles cause the samples to travel unevenly down the column and thus the components might not separate
(d) bubbles block the flow from the bottom of the column
(2) Spinach is green, however the pigments it contains are green, orange, yellow, and grey. Which of the following statements is true?
(a) Chlorophyll is grey and carotene is yellow-orange.
(b) Chlorophyll is green and carotene is yellow-orange.
(c) Chlorophyll is grey and carotene is green.
(3) A column chromatography procedure for the separation of a polar and a non-polar compound calls for sequential elution with the following two solvents:
methylene chloride
hexanes
Which solvent should be used first?
(a) methylene chloride
(b) hexanes
(c) it does not matter which solvent is used first
(4) What happens if you load the spinach pigment mixture onto the column in too much methylene chloride?
(a) the spinach pigments will not separate into individual components because they will travel rapidly down the column
(b) the spinach pigments will evaporate
(c) too much methylene chloride in the loading solvent will not affect the separation
(5) Of the following compounds, which will be the first to elute from an alumina chromatography column? Last?
(a) a will elute first and b will elute last
(b) d will elute first and c will elute last
(c) b will elute first and a will elute last
(d) b will elute first and d will elute last