Experiment#5: Chromatography Flashcards
Used to separate mixtures of compounds and identify an unknown.
Chromatography
Exploits the differences in solubility and adsorption
Chromatography
CHROMATOGRAPHY
A name/name of the phase for the porous material used in chromatography.
Adsorbent or Stationary Phase
CHROMATOGRAPHY
A name/name of the phase for the solvent that moves the mixture through the adsorbent.
Eluent or Mobile Phase
CHROMATOGRAPHY
Uses a solid stationary phase and a liquid mobile phase, wherein separation is governed by the surface adsorption phenomena.
Adsorption Chromatography
Refers to the ability of a substance to “stick” to a surface.
Adsorption
ADSORPTION CHROMATOGRAPHY
Molecules of interest which are getting adsorbed on the adsorbent.
Adsorbate
ADSORPTION CHROMATOGRAPHY
The extent of adsorption of a single component depends on which 3 factors?
- Polarity of the Molecule
- Activity of the Adsorbent
- Polarity of the Liquid Mobile Phase
CHROMATOGRAPHY
Uses a liquid stationary phase supported on the surface of a solid and a liquid or gas mobile phase which is insoluble in the stationary phase.
Partition Chromatography
CHROMATOGRAPHY
This type of chromatography is governed by differences in the solubility of the sample in the stationary and mobile phase.
Partition Chromatography
PARTITION CHROMATOGRAPHY
Separation is based on _______ ________ between two liquid phases.
Solute Partitioning
CHROMATOGRAPHY
A type of solid-liquid adsorption chromatography that uses a thin layer of adsorbent supported on a flat surface as the solid phase.
Thin Layer Chromatography
THIN LAYER CHROMATOGRAPHY
What are the 2 possible adsorbents found on the flat surface of a piece of glass or paper used as the solid/stationary phase?
- Alumina
- Silica Gel
THIN LAYER CHROMATOGRAPHY
A polar adsorbent that can hydrogen bond.
Silica Gel
TRUE or FALSE | THIN LAYER CHROMATOGRAPHY
Polar components of the mixture will interact less with the silica gel and move faster up the TLC Plate.
FALSE. Polar components will interact more, and move less quickly.
TRUE or FALSE | THIN LAYER CHROMATOGRAPHY
Non-polar compounds will move faster and migrate further up the TLC Plate.
TRUE
THIN LAYER CHROMATOGRAPHY
Provide at least 3 (or all) of the 5 purposes of Thin Layer Chromatography.
- Identify compounds/unknown mixtures
- Detect intermediates in reactions
- Determine the progress of a reaction
- Determine the number of components in a mixture
- Evaluate the efficiency of purification processes
CHROMATOGRAPHY
Technique for separating dissolved chemical substances by taking advantage of their different rates of migration across sheets of paper.
Paper Chromatography
CHROMATOGRAPHY
Used to separate and identify amino acids in a mixture.
Paper Chromatography
PAPER CHROMATOGRAPHY
Made of highly purified cellulose that absorbs and retains water (hydrophilic), serving as the stationary phase.
Filter Paper
PAPER CHROMATOGRAPHY
What is the solvent system for Paper Chromatography?
(Hint: 1:2 (v/v) 2% ______ _______-______ _______)
1:2 (v/v) 2% ammonium hydroxide-isopropyl alcohol
PAPER CHROMATOGRAPHY
The hydrophic organic solvent is drawn up the paper by ….?
Capillary Action
PAPER CHROMATOGRAPHY
A point where the sample is initially spotted on the paper.
Baseline or Origin
PAPER CHROMATOGRAPHY
The distance moved by the solvent along the paper.
Solvent Front
COMPLETE THE STATEMENT | PAPER CHROMATOGRAPHY
Separation takes place due to the A) _______ ______ of the components of the mixture for the B) ____ stationary phase and the mobile phase which is a relatively C)_____ solvent or solvent system.
A) Different affinities
B) Polar stationary phase
C) Non-polar solvent
PAPER CHROMATOGRAPHY
The rate at which the amino acid moves up the paper is related to its _____ ______ for the paper (which is hydrophilic) and the solvent (which is hydrophobic).
Relative Affinity
TRUE or FALSE | PAPER CHROMATOGRAPHY
Amino acids that are more soluble in the solvent will move less on the paper.
FALSE. They will move higher.
TRUE or FALSE | PAPER CHROMATOGRAPHY
Amino acids that are more attracted to the paper will move higher on the paper because they wish to cover more ground.
FALSE. They remain closer to the origin line.
PAPER CHROMATOGRAPHY
Once the chromatogram has dried, the amino acids can be visualized by contacging the dried chromatogram with a 2% ______ solution in acetone.
Ninhydrin
A substance that separates and moves constituents of a mixture through the column of a chromatograph.
Eluent
Building blocks of proteins.
Amino Acids
AMINO ACIDS
What are the 3 groups attached to an amino acid’s central carbon?
- Carboxylic Acid Group
- Amino Group
- R Group
[AFTER THE EXPERIMENT]
What would be the effect of this following error?
- The solvent in the developing chamber is higher than the spotted sample.
The spots will dissolve away
[AFTER THE EXPERIMENT]
What would be the effect of this following error?
- Too much sample is applied to the paper.
Deteriorates the quality of the separation (“tailing” occurs).
[AFTER THE EXPERIMENT]
What would be the effect of this following error?
- The paper is allowed to remain in the chamber after the solvent front has reached the top of the plate.
Solvent and sample would continue to move up and will all merge together at the top, eliminating any separation that happened earlier.
[AFTER THE EXPERIMENT]
Why is it necessary to cover the developing chamber tightly during the development of a chromatogram?
- Solvent vapor can saturate the air in the chamber to ensure maximum resolution between components.
- To prevent the solvent from evaporating.
What is the recommended size for samples during spotting?
1-2 Milimeters
