by Liz LaRosa
click here for a modified pdf version
Objectives:- To separate pigments found in markers. (Rose Art works the best. Do not use Crayola- won't separate)
- To determine the primary colors of pigments.
- To calculate the Rf value of primary colors.
- Filter paper
- Water
- Beaker
- Markers (3 per group)
- Pencil
- Ruler
- Calculator
- Cut round filter paper in half. Cut off one end to make a flat edge. ( will look like a sailboat sail)
- Measure 3cm from the bottom and draw a line across the width in pencil.
- Each group will have 3 markers: a primary color (red, yellow or blue) a secondary color ( orange, green, purple) and the last color is black or brown.
- On the starting line, dab one color at a time, about 10 times each. The 3 colors should not touch. You will have 3 dots on the starting line.
- In a beaker, add a small amount of water about 1 - 2 mL. The water should not touch the pigments!!!
- Place paper in beaker flat edge down and let sit 10 - 15 minutes.
- Take out paper and, with your pencil, follow the water line across to mark the boundary between wet and dry. This is your finish line.
- With your pencil, circle each pigment and label. (i.e. b for blue)
- Measure each of the 3 primary colors in cm from the starting line to where the pigment ended. Record in Table 1.
Data :
Table 1 - Observations of pigments (half page)
| Color | Distance Pigment cm | Distance Water Traveled cm | Rf Value = Pigment/Water |
| Red |
|
|
|
| Yellow |
|
|
|
| Blue |
|
|
|
Analysis/Results:
- Which color had the highest Rf value?
- Rank the colors from highest to lowest.
- Compare your results with the class. What were their Rf values? Do you notice any trends? Explain.
2-3 sentences on what you learned
