Scientists You Should Know
Dr. Katarena Ford uses LCMS (liquid chromatography mass spectrometry) to understand our bodies. LCMS uses the polarity and adsorption of liquids to separate and identify the parts of a solution or mixture. Meaning that because different things dissolve in different solvents and stick to different surfaces, we can separate them. That way we can figure out what’s in mixed up solutions like blood or urine or rain runoff or leaf juice or motor oil….
https://scholar.google.com/citations?user=QiD9tCQAAAAJ&hl=en. https://www.waters.com/blog/conversation-about-equity-in-stem/
A Tanta University lab group explored Ancient Egyptian water purification techniques to develop an inexpensive and straightforward way for residents to remove silt and sand from groundwater. Fabric Wicking Filtration depends on capillary action to separate water from its solids. The head of the lab is Dr. Mohamed Ayoub.
Check out some of the lab’s findings:
https://www.jstor.org/stable/jamewatworass.106.12.44
https://core.ac.uk/download/pdf/235050711.pdf
Introducing the Topic
Experiencing the Science
KiwiCo used to make a Science of Color box that included the two capillary action demos Science Mom talks about (above). The materials are straightforward except for the strips of filter paper. The cone-shaped coffee filters are about the right thickness. Or ChemEx filters.
The little cups are convenient for the “walking water” demo as well.
Thinking about the variables
I have always done a leaf chromatography demo that echoes the original chromatography experiments by scientists like botanist Mikhail Tsvet.
We always use a coin to “roll” the leaf material onto the filter paper.
Since we’re keeping the variable of the pigment mix constant, why don’t we try changing the solvent? I can think of three solvents of different polarities that are in my house: water, isopropyl alcohol, acetone, and vegetable oil.
Rubbing alcohol is the one people usually use. It’s hot and humid at my house, and I’m not having a ton of luck. I should try again inside.
Based on these messy data, I am inclined to wonder if the data suggest that different pigments dissolve better in different solvents and that none of the pigments dissolves in oil? I would want to compare to other scientists’ data. What solvent did Tsvet use?
This mortar and pestle method looks like it works better:
https://www.mybaba.com/leaf-chromatography-science-experiment/
Responding/analyzing
Multisensory
Walk through a puddle wearing pants that are too long, and you’ll notice the pants aren’t just wet at the bottom. (I learned this going to college classes in the 90s wearing JNCOs.)
Put white carnation stems in colored water to make a rainbow bouquet.
What about those reed oil diffusers? How does the oil climb the reeds?
Creative
Can the walking water method be used to make a tie-dye project? Use a dry shirt, some empty buckets or bowls, and 2-3 primary colored dyes.
Verbal
There are two little research projects here. One of them is this “fabric wicking” water purification method. Links to primary sources are provided above.
The second research project is the history around chromatography. Does Mikhail Tsvet deserve to be called the “Father of Chromatograpy”? Support your argument. Use the Claim-Evidence-Reason model.
Analytical
Why don’t you try the “fabric wicking” method? Does it matter what fabric you use? How does it compare to other types of filtration you’ve tried before? What would the method be like for trying?
Use the Engineering Design Process.