Chromatography: Who Wrote the Note?
Summary
In this chemistry lab, students will investigate who wrote the mystery note left in Ms. N's classroom saying they stole the class pet. There should be a variety of dark markers with names on them that were collected from all the students in Ms. N's room. Show students the ransom note written using a dark marker. Using different dark markers (water-based) students will test different markers to see what the chromatograph shows. Each brand of marker will have a combination of different pigments. The chromatograph that matches the pigment combination chromatograph of the ransom note will show what marker was used in the ransom note. Make the lab exciting for students by building up the mystery and their success in catching the person who wrote the note to help rescue the class pet!
CollapseLearning Goals
Concepts:
Students will learn how a crime laboratory can use chromatography to identify various inks.
Students will also demonstrate that black ink and other colors are actually a combination of different colors.
Students will also learn the importance of washable ink in this activity, as permanent marker will not separate.
Vocabulary:
-Chromatography
-Chromatograph
-Filter paper
-Crime lab.
Context for Use
Time Frame: 1-2 50 minute class periods.
Special Equipment: Filter Paper or Chromatogrpahy Paper (order in any science catalogue) Different brands of washable markers.
Description and Teaching Materials
1. Place various round marker dots 1/2 inch from the bottom of the strip of filter or chromatography paper.
2. Place the filter paper into a beaker so the marker dots are on the bottom of the paper. You might want to use a wooden skewer to hold up the paper so it does not sag in the water.
3. Gently pour water just under the 1/2 inch marker dots.
4. Let the paper sit in the water for 5 minutes and observe the changes as the water wicks up the paper.
5. Make comparisons to the ransom note.
6. Look for matches to the ransom note, and repeat if necessary.
The closure would be to solve the mystery and have students explain how they can prove their answers. Have students repeat the experiment with the marker that they think was used to write the ransom note. Students need to see that an experiment is repeatable.
Reference: www.kids.union.edu/fsnChromatography.htm
Teaching Notes and Tips
Include having made-up names written on the markers so students can solve the mystery of who wrote the note. Example: Mary's dark green marker matches the ransome note chromatograph. Mary might have written the note.
Students might be able to see all of the potential answers right away. Make the experiment tricky by having different brands of black washable markers instead of many different colors that are obviously not the right ones. Also, teachers need to test all markers before having students perform this experiment to work out any major glitches that might occur.
Assessment
Standards
I. HISTORY AND NATURE OF SCIENCE
A. Scientific World View The student will understand that communication is essential to science. 1. The student will know that current scientific knowledge and understanding guide scientific investigation.
2. The student will recognize that clear communication of methods, findings and critical review is an essential part of doing science.
I. HISTORY AND NATURE OF SCIENCE B. Scientific Inquiry The student will understand the process of scientific investigations. 1. The student will perform a controlled experiment using a specific step-by-step procedure and present conclusions supported by the evidence.
2. The student will observe that when a science investigation or experiment is repeated, a similar result is expected.