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→Method
====Identifying Chemicals by Comparison====
The [[chromatogram]] from an [[experiment]] can be compared against [[chromatogram]]s of known [[chemical]]s to identify the [[chemical]]s in the original sample.
#Take a piece of [[chromatography]] paper of [[width]] 2cm and [[height]] 10cm.
#Using a ruler draw a line with pencil across the [[width]] 1cm up from the end.
#Add a dot of the unknown sample on the pencil line.
#Suspend the [[chromatography]] paper in a suitable [[solvent]] just below the pencil line with most of the paper above the [[solvent]].
#Wait until the [[solvent]] stops rising up the paper.
#Compare this [[chromatogram]] to [[chromatogram]]s of known [[chemical]]s.
====Identifying Chemicals by R<sub>f</sub> Number====
The [[Retention Factor|R<sub>f</sub>]] values for a variety of [[chemical]]s are known. By comparing the [[Retention Factor|R<sub>f</sub>]] values from an [[experiment]] to the known values of different [[chemical]]s then the [[chemical]]s in the [[experiment]] may be identified.
#Take a piece of [[chromatography]] paper of [[width]] 2cm and [[height]] 10cm.
#Using a ruler draw a line with pencil across the [[width]] 1cm up from the end.
#Add a dot of the unknown sample on the pencil line.
#Suspend the [[chromatography]] paper in a suitable [[solvent]] just below the pencil line with most of the paper above the [[solvent]].
#Wait until the [[solvent]] stops rising up the paper.
#Use a ruler to measure the distance that the [[solvent]] has traveled up the paper.
#Use a ruler to measure the distance that the [[chemical]] has traveled up the paper.
#Use the equation:
:<math>R_f = \frac{d_c}{d_s}</math>
:Where:
:R<sub>f</sub> = [[Retention Factor]]
:d<sub>c</sub> = distance moved by the [[chemical]]
:d<sub>s</sub> = distance moved by the [[solvent]]
#Compare this value to the values for known [[chemical]]s.