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Purpose:
The purpose of this lab is for students to observe the separation of a mixture through the process of paper chromatography. This process mimics similar processes used in crime labs. This lab has been adapted from the GEMS hall of science "crime lab chemistry" Before working on this lab students should read the poisoned needle mystery.
Procedure:
Using the materials provided, attempt to determine the pen that wrote the secret note. Each pen will have a signature that you can determine by testing the pen's ink, separating it with the method of chromatography demonstrated in class. You will then be given a sample section of the secret note. Attempt to determine this pens' identity by matching it with the samples that you have made. Attach your samples to a piece of paper to hand in with your lab report.
Materials:
pens
water
filter paper
straws
tape
cups
Discussion Questions:
1. Describe in your own words how chromatography works.
2. Why do you think each pen exhibited a different signature band of colors although they all write black?
3. What other materials would you like to try as a solvent?
4. Which materials appeared to be the most soluble in water and why do you say this?
Need help ? check here Chem4Kids! Your Chemistry Website at the mixtures section.
To go beyond: (for an A grade, complete one of the activities below.)
1. Plants also have interesting pigments. (spinach, cabbage, flower petals, algae) Prepare some chromatography samples of plant pigments by rubbing the leaves on a piece of filter paper scratch the plant against the paper with a blunt object like the edge of a coin, use alcohol as your solvent and you will see some intriguing results.
2. Food coloring can also be separated using alcohol as the
solvent. Put a drop of food coloring on a piece of filter paper and
see the colors emerge when you use the chromatography method
described below.
Put the food coloring droplet on a piece of filter paper. Put a piece
of pipe cleaner through the filter paper. Put the end of the pipe
cleaner in a plastic cup containing alcohol. Watch for the
results.
Interested in more home labs? Check here home labs or you can with beakman and jax
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