The fraction of sample in the stationary phase in reverse phase liquid chromatography will increase when water is added to the mobile phase. Why?

True or False: Liquid-solid  phase column chromatography is used to separate large up to multigram amounts of mixtures, based on their differences (however small) in polarity.

The solid material in column chromatography is typically referred to as: O 1) the stationary phase 2) the mobile phase

Which form of chromatography is INCORRECTLY defined? A. partition chromatography – solute equilibrates between the stationary liquid and the mobile phase B. affinity chromatography – solute binds to a molecule specific for the solute C. molecular exclusion chromatography – solute is separated based on size D. adsorption chromatography – solute is adsorbed into solid particles E. ion-exchange chromatography – solute ions of the opposite charge are attracted to the stationary phase

You are carrying out an experiment by analysing alcoholic drinks by gas chromatography. Why is Gas chromatography the best technique used for this analysis? Why is Carbowax a suitable stationary phase for this analysis? What gases are used and what is their purpose and source?

Describe 4 similarities and 4 differences between Thin layer chromatography (TLC) and column chromatography.

a) What would you see if you ran a Thin Layer Chromatography (TLC) on a mixture of the three solids shown below using silica gel as the stationary phase and ethyl acetate/hexanes as the mobile phase? Whichsolid would have the highest Rf and which would have the lowest Rf? Explain  b) Would changing the mobile phase (from part a) and increasing thepolarity by introducing small amount of methanol to the mobile phase change the order ofRf of the above 3 compounds? Explain  c) Another type of chromatography is Reverse Phase Chromatography. In this type ofchromatography, the stationary phase is non-polar and the mobile phase is polar. If astudent performed Reverse Phase TLC on the mixture of 3 solids (from part a),what would be the order of Rf’s of the compounds? Which would have the lowest Rf andwhich would have the highest Rf?

Why do H2 and He allow more rapid linear flow rates in gas chromatography than does N2, without loss of column efficiency

Chemistry Suppose you are trying to separate a mixture of compounds using reversed-phase liquid chromatography (RPLC). On the first run, using a mobile phase containing 40% tetrahydrofuran and 60% water, the peaks all elute between 0 and 3 min and are too close together to be quantitatively resolved. To improve the resolution of the peaks, should you increase or decrease the amount of tetrahydrofuran in the mobile phase for the next run? Incorrect. decrease increase The solvent tetrahydrofuran is less polar than water. In RPLC, a nonpolar stationary phase and a polar solvent is used for the separation. Eluent strength of the mobile phase increases as the polarity decreases. Decreasing the eluent strength of the mobile phase will result in an increase in the retention time and improved resolution of the compounds. not enough information In a separate experiment, you are trying to separate a mixture of compounds using normal-phase liquid chromatography (NPLC). On the first run, with a…

In molecular exclusion (size exclusion) chromatography, the molecules have the longest retention times. a) the larger molecules b) the smaller molecules