Lab 3B; Oct 19th, 2010; by: Mandy Xiao

Separation of a Mixture by Paper Chromatpgraphy

Some vocabularies you should know:

Rf value: the ratio of the distance traveled by the solute to the distance traveled by the solvent

Formula: Rf=d1/d2

D1 = distance traveled by solute

D2 = distance traveled by solvent

*Rf values vary from 0 to 1
capillary action: in this case: when water is moving up the paper

solute front: (in this experiment) food colouring

solvent front: (in this experiment) water

Lab procedure:

Part 1: Setting Up

3 large testubes & 3 Erlenmeyer flasks. Label A, B, C

22cm chromatography paper

Use pencil to draw a line across strips 4cm from one end

Trim the end of the strip

Place 2cm deep water into each test tube

Part 2: Rf values of individual food colourings

Use a glass stirring rod to spot the strip with the colour

Write the colour at the top of the strip

Insert strip in test tube A

Observe the sample spot as the water goes up

Observe solute front and solvent front

Remove strip from the test tube. Immediately draw a pencil line across the top edge of the solvent front

Measure d1 and d2 calculate Rf for sample and record

Part 3: Separation of Mixtures onto Their Components

2^nd strip with green colour, 3^rd strip with unknown LABEL!

Insert strip in test tube B&C (see procedure in Part 2)

Record data on table 3!

Further Information: 

  The substances (solutes) to be analysed must dissolve in the solvent, which is called the mobile phase because it moves. The paper or thin layer of material on which the separation takes place is called the stationary or immobile phase because it doesn't move.

INTERESTING! Paper chromatography Art!