Investigating Compositions: Using Chromatography to Explain Color Patterns
Initial Publication Date: August 25, 2009
Summary
In this chemistry lab experiment, students explore the properties of color using chromatography. Students will observe and compare color patterns to differentiate compositions of various colors.
CollapseLearning Goals
1. Using their chromatography results, students will be able demonstrate that some colors are made up of other colors.
2. Students will be able to compare black markers of different brands and examine different color pattern results among the various brands.
3. The students will be able to explore how scientists use chromatography in the world today.
4. The students will be able to develop questions and predictions based on the results of the chromatography experiment.
2. Students will be able to compare black markers of different brands and examine different color pattern results among the various brands.
3. The students will be able to explore how scientists use chromatography in the world today.
4. The students will be able to develop questions and predictions based on the results of the chromatography experiment.
Context for Use
This activity is best suited for grades 3-5, but could be modified for higher or lower levels. This is a lab activity paired with a classroom discussion and optional outdoor observation. The time period is 1-2 class periods. Students should not need prior knowledge on the concepts. (The optional outdoor observation of this activity is best done in the fall to link chromatography with the color change in leaves).
Description and Teaching Materials
Materials:
2 beakers filled 1/8 with water
1 pack of Sanford or Crayola water-soluable
markers
4 black markers made by different brands
1 Pencil
1 Permanent marker
2" by 6" filter papers or paper towels
Masking tape
Chromatography Results Sheet
Science journals
Lesson Introduction
The teacher will write the word chromatography on the board and explain that chromatography is the separation of ink colors by allowing a solvent to seep up filter paper so that the ink dissolves and separates, often in many-colored layers.
The teacher will make a real-life application of chromatography and explain that chemists use chromatography to separate the chemicals in a mixture so each chemical can be analyzed. The teacher will explain that medical chemists use chromatography to find certain chemicals in a person's blood. They will further explain that environmental chemists use chromatography
to find pollutants in water and other substances.
Lesson Activity
The students should write the pen number on a piece of masking tape with a permanent marker and place it at the top of the strip. The students will then take a red marker and make a line going across the paper 1/4 of the way from the bottom of the filter paper. They will dip the filter
paper in the beaker with the water in it. Then
hang the paper strip in the cup, making sure the ink line
does not touch the water– only the bottom of the filter
paper. (See attached diagram).
They will let the filter paper absorb the water and notice changes in color. They will repeat the above procedure for
the colors yellow, blue, purple, orange, brown and black. They will then test the black markers using the same process. Students should complete the paper chromatography lab results sheet.
Ask students to generate questions about the colors that did not show a change. The students will discover which colors are the primary colors. These are the colors that will not show a change in color when the filter paper absorbs the water.
Ask students to generate questions about what happened to the liquid in the beakers when the paper was placed in it. They will also discover that the water goes up the paper
towel/filter paper. This happens because paper towels have holes which pull the water up. This is called the capillary reaction.
Students will also develop testable questions related to this activity and write them in their journals for potential testing at a future date. They will also journal about their results of the experiment and what surprised them in this activity.
Optional Extension Activity: Use the process of chromatography to make outside observations in the fall and answer the questions:
1) Why do some leaves look green and others look purple?
2) Why do leaves turn color in the fall? Student Data Sheet & Diagram For Paper Chromatography Lab (Microsoft Word 34kB Aug25 09)
2 beakers filled 1/8 with water
1 pack of Sanford or Crayola water-soluable
markers
4 black markers made by different brands
1 Pencil
1 Permanent marker
2" by 6" filter papers or paper towels
Masking tape
Chromatography Results Sheet
Science journals
Lesson Introduction
The teacher will write the word chromatography on the board and explain that chromatography is the separation of ink colors by allowing a solvent to seep up filter paper so that the ink dissolves and separates, often in many-colored layers.
The teacher will make a real-life application of chromatography and explain that chemists use chromatography to separate the chemicals in a mixture so each chemical can be analyzed. The teacher will explain that medical chemists use chromatography to find certain chemicals in a person's blood. They will further explain that environmental chemists use chromatography
to find pollutants in water and other substances.
Lesson Activity
The students should write the pen number on a piece of masking tape with a permanent marker and place it at the top of the strip. The students will then take a red marker and make a line going across the paper 1/4 of the way from the bottom of the filter paper. They will dip the filter
paper in the beaker with the water in it. Then
hang the paper strip in the cup, making sure the ink line
does not touch the water– only the bottom of the filter
paper. (See attached diagram).
They will let the filter paper absorb the water and notice changes in color. They will repeat the above procedure for
the colors yellow, blue, purple, orange, brown and black. They will then test the black markers using the same process. Students should complete the paper chromatography lab results sheet.
Ask students to generate questions about the colors that did not show a change. The students will discover which colors are the primary colors. These are the colors that will not show a change in color when the filter paper absorbs the water.
Ask students to generate questions about what happened to the liquid in the beakers when the paper was placed in it. They will also discover that the water goes up the paper
towel/filter paper. This happens because paper towels have holes which pull the water up. This is called the capillary reaction.
Students will also develop testable questions related to this activity and write them in their journals for potential testing at a future date. They will also journal about their results of the experiment and what surprised them in this activity.
Optional Extension Activity: Use the process of chromatography to make outside observations in the fall and answer the questions:
1) Why do some leaves look green and others look purple?
2) Why do leaves turn color in the fall? Student Data Sheet & Diagram For Paper Chromatography Lab (Microsoft Word 34kB Aug25 09)
Teaching Notes and Tips
Sharing the groups' testable questions is very important. I also give students an additional opportunity to do an experiment with these testable questions. To link to the optional extension activity, this lesson is best done in the fall season.
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Assessment
Formative or formal assessment of student data sheets and journaling can be used as an indicator of understanding. Student participation and responses may also be used as assessment.
Standards
4.2.1.1.1 - Objects have observable properties that can be measured.