Pigment and Chromatography Lab

 

1.  Divide up your lab tables into two groups and assign each group an activity to be responsible for setting up and collecting the data.

2.  Share the data only with the other group.

3.  Work on post lab questions together as a lab table.

 

Activity 1 Directions: 

  1. Cut a piece of filter paper 1cm x 10cm (done for you).
  2. Measure 2 cm from the bottom end and draw a line with a pencil.
  3. Using the black overhead marker, make a dot in the center of the pencil line.  Record the color of the dot in your data table.
  4. Place the filter paper in the graduated cylinder (or test tube) according to the teacher demo.
  1. Allow the paper to sit in the water for about 20 minutes.  
  2. When complete, remove the paper from and allow to dry.  While it is drying, record the pigment colors you see on the paper in the data table
  3. When the paper is dry, use a ruler to measure the furthest distance (in mm) each color traveled from the starting line.  Record in data table.
  4. Draw an exact colored copy of your paper in your notebook underneath your data table.

 

Activity 2 Directions:

  1. Cut a piece of chromatography paper 1cm x 10cm (done for you). 
  2. Measure 2cm from the bottom end and draw a line with a pencil.
  3. Using a pipette, drop some leaf pigment onto the chromatography paper on the pencil line.  Refer to the teacher demo.  Record the color of the dot in the data table.
  4. Place the chromatography paper in the graduated cylinder (or test tube) with chromatography solution according to the teacher demo.
  5. Allow the paper to sit in the chromatography solution for about 20 minutes.
  6. When complete, remove the paper from the beaker and allow to dry.  While it is drying, record the pigment colors you see on the paper in your data table (the golden pigment near the top is carotene, the bright green pigment is chlorophyll a, the olive green pigment is chlorophyll b, and the lighter yellow pigment is xanthophyll.  You may or may not see all four different pigments.).
  7. When the paper is dry, use a ruler to measure the furthest distance (in mm) each color traveled from the starting line.  Record in data table.
  8. Draw an exact colored copy of your paper in your notebook underneath your data table.

Data Table:  You need to make a data table for each activity that includes the following:  original color of activity substance, color of pigments after separation, distance each pigment traveled in mm (not original color).

Post Lab Questions:

  1. For activity 1, list the pigments in order from furthest traveled to least traveled. 
  2. Repeat for activity 2.
  3. The movement of pigments during Chromatography is based on how well the pigment dissolved in the solvent (pigment solubility) and how well the pigment sticks to the paper (pigment resistance).  For example, let's say a the blue pigment traveled further than the yellow.  This could mean that the yellow pigment has more resistance in the paper or that it is less soluble than the blue pigment.   Based on this information, what can you conclude about the pigment that moved the farthest in activity 2?
  4. What are pigments?  What function do they have in photosynthesis?
  5. What are two types of pigments found in plants?
  6. Why do plant leaves appear green?
  7. Based on this activity, why do some plants turn from green to yellow in the fall?

 

Write up:  Done in notebook and includes...

            1.  Complete data tables for each activity

            2.  Underneath each data table is an exact drawing of the pigments from that activity

            3.  Answers to post lab questions