Chromotography Flashcards
Name a common solvent used in the experiment
Water
How should the chromatography paper be once in the water?
Still and not touching and sides or the bottom
Where should you mark a line on the paper?
2cm up from the bottom
What should you use to mark the line?
A pencil
Why should it be marked in pencil?
Since pencil doesn’t run it won’t interfere with the results
What is the line in pencil known as?
The baseline
Why should the inks not be permanent markers?
Since these inks won’t run in water solvents
Why should you only put a small dot of ink on the paper?
To ensure accurate results, if the ink dots are too big the residues may run into eachother
Once the chromatography paper has the inks on it, what is next?
You must attach the paper to the pencil so the paper can hang in the beaker
Why should we take the paper out and then add the water, as a pose to adding water whilst the paper being in the beaker?
If any water spills onto the paper we will have to restart the experiment again
Once the water in the beaker, what is next?
You must now put the paper into the beaker
What should we make sure to do?
Keep the beaker still and not let any of the paper touch the sides or the bottom
How long should we leave the paper and beaker still for?
20 minutes
What must we do after the 20 minutes?
Take the paper out and leave the chromatogram to dry, making sure to hang it
Why must we not lie the chromatogram flat?
The inks will smudge if we lie it flat
Why must we leave a large gap from the top of the die to the top of the paper?
This is because the residue moisture in the paper will continue to rise in the chromatogram until is has come off the paper
Why must we account for a large gap from the top of the die to the top of the paper
This is because the residue moisture in the paper will continue to rise in the chromatogram until is has come off the paper
What is the solvent front?
The furthest point the water has risen up the chromatogram/paper
What is the solvent front distance?
The distance from the solvent front to the baseline
When analysing the dried chromatogram, what must we do?
Mark three points at the darkest colours of each ink and calculate the distance of the three point from the baseline, individually
Why might we not measure the distance of some of the inks?
This may be because they have not left the baseline and are insoluble in water
How do you calculate the Rf value?
Distance travelled by substance/Distance travelled by solvent.
What units is the Rf value in?
Nothing as we are dividing mm by mm
Why do we measure the solvent front and substance distances in mm
To obtain more accurate results
