Chromotography

Chromotography

1. It is used to identify substances in a mixture

   • Different substances wash through wet filter paper at different rate

2. Method:

   • 1. Draw a pencil baseline on filter paper and put dots of each mixture on the line
     • 2. Roll up the piece of paper and put it in a beaker containing water
       • 3. you must make sure the baseline is kept above water level
         • 4. The water will seep up the paper, taking the water with it
           • 5. The different chemicals on the paper separate different spots on the paper
             • 6. The result of the chromatography test is called a chromatogram
               • A Chromatogram with 4 spots means there is at least 4 different substances in the sample mixture

3. Uses for this:

   • to separate out the mixture of colouring agents in food

4. You can calculate the Rf value for each chemical

   • Rf= Distance travelled by substance (e.g. food colouring) /distance travelled by solvent (e.g. water)