(i) State why the solvent level should not be above the base line at the start of the experiment.
To prevent the in the .
Mmuae Afoforo a Wobɛpaw:
solvent
dissolving
inks
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Method for making a chromatogram.
Leave the paper in the beaker until the water reaches near the top of the paper.
Take the paper out of the beaker
use a pencil to mark the location of the solvent front
the level the water has reached
Leave the chromatogram to dry.
Draw a pencil line on the paper, about 2 cm from the bottom.
Put a small spot of ink from each pen on your pencil line.
Pour some water into the beaker to a depth of about 1 cm.
Lower the chromatography paper into the beaker
The bottom of the paper is in the water
The water level is below the spots.
Method to determine a Rf value
To calculate the Rf value use the expression Rf = distance travelled by dot / distance travelled by solvent front.
First measure the distance from the pencil line to the solvent front (with a ruler).
Then measure the distance from the pencil line to the centre of the dot (with a ruler)
(i) State why the solvent level should not be above the base line at the start of the experiment.
To prevent the in the .
(ii) Explain which dye, present in one of the inks A, B, C, or D, is also present in ink P.
(iii) State why ink D does not move during the experiment.
Calculate the Rf values
Distance travelled by A =
Calculate the Rf values
What is the Rf value?
Match the labels
The bottom of paper must be
The pencil line must be
A
B
C
X
one dot only
two or more dots
Pure sample
Mixture
Sample
A
B
C
D
Safe to drink
Not safe to drink
Select the correct option.
Note - the more soluble a dye is the further the dot will move.
Note - the more soluble the dye the larger the Rf value will be.
Note - the Rf value can not be more than 1.
Rf =
Rf =
Note - the soluble a dye is the further the dot will move.
Note - the more soluble the dye the the Rf value will be.
Note - the Rf value can not be more than .
How many dyes are there is A
How many dyes are there in B
How many dyes are there in D
How many dyes are there in X
Which dye is not found in sample X
Start line not drawn in so line will
Samples are in the so the samples will in the water instead of moving up the .
Sample B did not move as sample is soluble in the solvent used.
To fix this we would use a solvent, for example alcohol or propanol in which sample B soluble
