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3.7 Separations of solutions and mixtures chromatography

Solutions, also sometimes called homogeneous mixtures, can be solids, liquids, or gases. In a solution, the macroscopic properties do not vary throughout the sample. In a heterogeneous mixture, the macroscopic properties depend on location in the mixture.

Solution composition can be expressed in a variety of ways; molarity is the most common method used in the laboratory.

M = nsolute /Lsolution

 

Chromatography-

Retention Value-A particular compound will travel the same distance along the stationary phase by a specific solvent (or solvent mixture) given that other experimental conditions are kept constant. 

(The solute and solvent front will be proportional, no matter what size paper you use)

Rf value=

Distance Baseline travelled by (Center of ) the Solute
Distance Baseline travelled by Solvent (solvent Front)

Unknowns can be matched up to known compounds by their Rf value.

 

 

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