Our Autumn Leaf Lab

This year we seemed to have just enough good weather conditions to have beautiful fall colors for Washington state (warm days, cool but not freezing nights).

Working our way through the Periodic Table, we came to magnesium, which is to chlorophyll as iron is to hemoglobin.

These are easy experiments, and if you have autumn leaves, it's a perfect time to do them. Pluck a variety of leaves, cut or tear them into cups. Add alcohol (isopropyl, ethanol, or even alcohol-containing hand wash will do in a pinch) and mash them up with a spoon. Cover with foil and let stand for 1 hour. Then cut strips of coffee filters into the solution and watch for colors that migrate up the filters.


We generated hypotheses before starting the experiments. Hypothesis #1: In plants that drop their colored leaves, the change in color is due to a loss of pigment, rather than an increase in pigment (for instance, yellow leaves have lost their green, not gained yellow). Hypothesis #2: Plants with colored leaves that do not drop have an increase in a new pigment rather than pure loss.

I'm not completely sure you can see the results, but it was interesting. For the red and purple bushes, we could see an extra band of blue that wasn't present in the green or yellow leaves. Chlorophyll a is blue-green and chlorophyll b is yellow-green. It seemed as if the red and purple leaves had chlorophyll a.

We also made other observations as through the course of the experiment. We found the yellow leaves were the easiest to dissolve with alcohol (due to early breakdown of their cell walls?) and thought about the various designs of the leaves. The big maples seemed particularly well designed to catch sunlight (large surface area), but perhaps the addition of blue chlorophyll conferred some energy advantage on the smaller red leaved bushes? Also the bushes had more leaves and were much smaller than the big maples.

When we looked back at our hypotheses, it looked like the behavior of the green and yellow leaves supported Hypothesis #1. Although it doesn't show clearly in the picture, we extracted much more chlorophyll from the green leaves than the yellow. Hypothesis #2 was less clear because we used two red / purple-leaved bushes, one that dropped its leaves, and one that didn't. Both seemed to have both yellow-green and blue-green chlorophyll, and we couldn't determine quantity. Not surprising, more sampling would be necessary to determine something like this!

Early Science and the Study of Chlorophyll and Photosynthesis
Science of Fall Color pdf

Rough Science

My son has a 2 week break from his Great Books & Latin courses so we've been catching up on science labs. I'm beginning to think that like the need to teach practical theology within the context of our post-modern world, there is also a need to teach science recognizing that we live in a post-modern world.

One common mistake of today's post-modern man or woman is realizing we often know less than we really think we know. For the post-modern science student, the ignorance may be even greater because they lack enough world experience to see how much occurs without a carefully designed lesson plan. When we memorize a list or table of facts, do we really know it? So what is it that we do know, and what is it that we don't?

One nice discovery on my search for links to complement our Fizz, Bubble, and Flash experiments, was the Rough Science science reality show. If you are a Netflix subscriber, you can stream these episodes any time for free. A team of scientists (chemist, physicist, biologist) is dropped in a deserted area with few materials and a challenge to design, make, or find something in the surrounding terrain. How many of us can do this? Maybe we need to think more about our science and get out of the printed page. The first episode we watched challenged scientists to find gold in a gold mining area, purify it and quantitate it using only materials they could find in deserted saw mill.

The experiments we tinkered with this week included Electrolysis of Water using a 9 volt battery, water, and copper wires. The Rough Science team washing using electroysis to make silver iodide so that they could make a camera.



To top off our electrolysis learning we also watched this homemade Exploding Hydrogen video. It was pretty good! Even the outtakes!
Some Rough Science Challenges
Make Your Own Compass, Sea Water Batteries, Silver Iodide via Electrolysis for Camera

The History of Chemistry

The earliest history of chemistry is murky because many of the activities of early chemists or alchemists was shrouded in mysticism (fire, black magic) or greed (making gold). Many of the earliest dabblers in chemistry or alchemy acted in secret or were quietly funded by wealthy individuals hoping to grow wealthier.

In the 1500's, Theophrastus Paracelsus was a colorful personality who became interested in rescuing chemistry from the alchemists who were motivated by "pagan natural philosophy", instead finding a Christian alternative use for the chemical sciences. Paracelsus was interested in how chemistry could be used to help free people from disease.

From the Catholic Encyclopedia: "He sought the cause of pathological changes, not in the cardinal humours, blood, phlegm, yellow and black gall (humoral pathology), but in the entities, which he divided into ens astrorum (cosmic influences differing with climate and country), ens veneni (toxic matter originating in the food), the cause of contagious diseases, ens naturale et spirituale (defective physical or mental constitution), and ens deale (an affliction sent by Providence)..."

Modern chemistry took another great leap when Robert Boyle decided to use his scientific expertise "to seek for God's purposes in nature. His Skeptical Chemist was an important work, moving chemistry from the world of alchemy into the realm of science. Boyle believed the orderliness of the universe reflected God's purposeful design. God established the universe according to certain natural laws, so that it worked like a mechanical clock, once the Designer had set it in motion. The scientist's duty was to discover what laws God had established. Boyle himself formulated what became known as "Boyle's Law:" the pressure of a gas is inversely proportional to the
volume it occupies."

For a pretty interactive Periodic Table clickhere.





We're working our way through the experiments in Fizz, Bubble, and Flash. It has plenty of cartoons, silly jokes and poems, and easy-to-perform home experiments.



Wikipedia: History of Chemistry
Chemistry Lab Demo Movies at Purdue (QT)
More Home Chemistry Ideas:
Popular Science
Makezine