Doing Forensics with Paper Chromatography!

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Updated on May 08, 2013

Type

Chemistry

Grade

Elementary - Grades 4 and 5

Difficulty of Project

Medium

Cost

$ 10

Safety Issues

Wear safety glasses and apron or old shirt as a lab coat.

Material Availability

The materials are readily available from the local stationary store and super market.

Approximate Time Required to Complete the Project

One week. This includes collection, recording and analysis of data, summary of results and completion of bibliography.

Objectives

To determine whether colors such as black, brown, orange and purple are pure colors or mixtures of other colors by using paper chromatography.

Materials and Equipment Required

  • Non-permanent markers: black, brown, orange and purple
  • 2 large coffee filters
  • scissors
  • 4 pencils
  • centimeter ruler
  • tape
  • 4 medium plastic cups or medium sized jars
  • 4 flat plastic plates
  • 4 small plastic baggies
  • measuring cup
  • large bottle of tap water.

Introduction

Background Information

On the information level students will acquire some basic information on physical and chemical changes and on the process of paper chromatography involving the physical separation of mixtures of primary colors. They will observe a variety of changes actually observing the flow and separation of the components. They will research the various uses of chromatography such as in crime scene investigations, by pharmaceutical companies in analyzing the amounts of specific chemicals in their products, by hospitals in determining the alcohol in patients’ blood, by environmentalists in studying the level of pollutants in our water supply. Students will not only experience an example of the process but in combination with armchair research see the direct and practical applications of this process to daily life.

On the experimental level, this science fair project serves to acquaint students with the essential processes of sciencing such as the importance of the use of a control, of identifying dependent and independent variables, of data collection, of pictorial and graphic presentation of data and of being able to make better judgments as to the validity and reliability of their findings. They take on the role of scientists and in the process they learn to act as one.

Research Terms

  • chromatography
  • permanent colors
  • mixtures
  • solvent
  • solute
  • water solubility
  • water soluble materials
  • compounds
  • capillary action
  • adhesion
  • cohesion
  • adsorption
  • absorption
  • rate of absorption
  • forensics
  • chemical change
  • physical change

Research Questions

  • What is chromatography?
  • Who invented paper chromatography?
  • If you analyzed the parts of the word, chroma and graphy, what would be the definition of the term?
  • What are mixtures and how are they made?
  • What are compounds and how are they made?
  • What are the differences between physical and chemical changes?
  • How would you define a physical change, a chemical change?
  • What is capillary action?
  • What is adhesion?
  • What is cohesion?
  • What are solutions?
  • What are primary colors?
  • What are secondary colors?
  • What are some practical uses of paper chromatography?
  • Are there other types of chromatography? What are they and how are they used?

Terms, Concepts and Questions to Start Background Research

  • What is a control? A control is the variable that is not changed in the experiment.
  • What purpose does a control serve? It is used to make comparisons as to what changed or possibly caused the change.
  • What are variables? Variables are factors that can be changed in an experiment.
  • What is an independent variable? The independent variable is the one that is changed in the experiment.
  • What is a dependent variable? The dependent variable is the one that changes as a result of the change in the independent variable.

Charting and Graphing Data

In each section of the experiment, use charts to display the obtained data such the following sample:

Color of Markers

Colors Before Chromatography

Colors After Chromatography

Black

Brown

Orange

Purple

Experimental Procedure

  1. State the problem you are going to investigate in this science fair project.
  2. Create and reproduce the data sheets you will use to record your observations.
  3. Put on your safety glasses, apron or old shirt used as a lab coat. .
  4. Gather all your materials.
  5. Line up 4 jars, label each one with the name of color of the marker you are testing, black, brown, orange and purple.
  6. Prepare your chromatography strips. Use the coffee filter s and cut out at least 8 strips in case you make a mistake. Measure the length of the jars so that the strips can be rolled and taped around a pencil. The pencil will sit across the top of the jar and the strip should reach just about the bottom of the jar. Make the strips 1 inch wide and as long as you determined from your length measurement.
  7. With your pencil draw a line on each of the strip that is 2 cm from the bottom.
  8. Using each one of your magic markers, just above the pencil line made a dot. You will have 4 strips each having one dot of a different color.
  9. Using the measuring cup or graduated cylinder pour a small amount of water in each jar, the same amount in each jar.
  10. Tape each paper strip to a pencil and place each pencil across each jar. Check to see that the strip just touches the surface of the water. Keep it away from the sides of the jar.
  11. Keep the strips in the jars for five minutes.
  12. Remove each strip and place them on plastic plate to dry.
  13. Observe what happened to each strip recording your information in your chart.
  14. When the strips are dry place them individually in the plastic baggies to use in your final report and or display.
  15. Prepare your report and include all of the following: a clear statement of the problems, your hypothesis, List the materials used. Include the safety precautions taken. Describe the procedures used. Include all the data that were gathered. Include your chart. Formulate your conclusions. For dramatic value, you may include photos of the materials used or of you in the process of conducting this investigation. Include a bibliography of sources you used. You may wish to assess what you did and describe what you would do differently if you were to do this project again.

Bibliography

  1. http://www.chem4kids.com
  2. About.com Chemistry Anne Helmenstine, Ph.D.
Dr. Muriel Gerhard (Ed.D.) is a retired educator with fifty seven years of experience in all aspects of public education. She has been a teacher, principal, administrator, college professor, researcher, grants writer, change agent and science editor. She is the author of several books on education used as college texts. These include the best selling Effective Teaching Strategies with the Behavioral Outcomes Approach and The Behavioral Outcomes Handbook for Teachers and Administrators. Presently she is a consultant in science education and curriculum development, a marriage and family therapist, a newspaper columnist and an author. Her latest book, recently published, is a memoir of sixty vignettes entitled Ć¢Now That I`m Dead, I Decided to Write this Book."

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