Separation of a Mixture by Paper Chromatography

Before this lab, 3 tables from the text book were to be copied down onto paper.  This lab had 6 objectives:
To assemble and operate a paper chromatography apparatus
To study the meaning and significance of Rf values
To test various food colorings and to calculate their Rf values
To compare measured Rf values with standard Rf values
To separate mixture of food colorings into their components
To identify the components of mixtures by means of their Rf values

The supplies were:
5 stirring rods
scissors
3 large test tubes
3 Erlenmeyer flasks
Ruler
Chromatography paper strips
Food colorings (assigned either yellow, green, blue, or red)
Unknown mixture of food colorings

Part I: Setting Up
Obtain 3 Erlenmeyer flasks and 3 pieces of chromatography paper.  Draw a line at 4 cm into the paper and then cut the edges to make it into a arrow shape. Then place 2 cm of solvent into the flasks.

Part II: Rf Values of Individual Food Colorings
One food coloring was assigned either red yellow or blue.  On the center of the line that was drawn on the chromatography paper, the color that was assigned was to be spotted onto the center of the line. Next the strip was to be inserted into the test tube.  Once that was placed, observe the sample spot and make any observations in the next 20 minutes.  While that was happening, move onto the next part of the lab, the green and unknown food colorings.  Observe any changes with those two colorings as well.  After the solvent and food coloring sample have moved up and no longer moved, take them out and using the ruler measure how much cm the solvent and food coloring sample moved.  Record these on the tables that were drawn before the start of the lab.  Then clean up and continue onto the lab report. 

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