(c) Chemical analysis Flashcards
What is chromatography?
A technique used for analysis.
What are the 2 phases in chromatography?
Mobile and stationary phase.
What are the 4 types of chromatography?
- Paper
- Thin layer (TLC)
- Gas
- HPLC (High Performance Liquid)
What is the stationary phase in paper chromatography?
Paper.
What is the mobile phase in paper chromatography?
Solvent.
If a substance is soluble in the solvent what will this mean for the distance it will travel?
It will travel further.
Substances which have a higher affinity for the stationary phase will travel …?
Less far.
What is the stationary phase in thin layer chromatography?
Glass with a thin layer of cellulose or silica.
What is the mobile phase in thin layer chromatography?
Solvent.
Why is thin layer chromatography better than paper?
The mobile phase move more quickly through the stationary phase.
The mobile phase moves more evenly through the stationary phase.
There is a range of absorbencies for the stationary phase.
What are the 2 things that affect how far molecules move in chromatography?
Size and polarity.
Will bigger molecules move farther or shorter than smaller molecules?
Larger molecules will take longer to move whereas the smaller molecules are more mobile.
If a polar solvent is used which type of molecules will move further and why?
Polar molecule will move further as they are more strongly attracted to the solvent than non-polar molecules.
What is the RF value?
The distance that a certain spot moved in comparison to the overall distance that the solvent moved.
What is the formula to work out the Rf value?
Distance traveled by component/
distance traveled by solvent
