Now for a little Tuesday treat we have a guest post from a dear friend of the show, current science illustrator and future museum evaluator Juliana Olsson! She wrote us up a post about her experience as the Iron Science Teacher competition held on June 25th, 2011. Enjoy! – Ryan
I have a confession: before attending the Iron Science Teacher competition at the Exploratorium a few Saturdays ago, I had never watched any “Iron [Fill in the Blank]” activity. It’s not that I discriminate against element 26, I just have a hard time reconciling the competitive nature of such events with the subjective topic: if each entry is good but in different ways, how do you choose the “best” one? Thus I was somewhat wary watching high school science teachers duke it out in front of a live audience to determine which one could come up with the best experiment and lesson plan on a given concept. Would this be a ferociously ferrous nerd bloodbath?
I shouldn’t have worried. It was awesome. There were chemicals and beakers and flames and muppet music. Things were learned, fun was had by all, and I approved of the winner. There was even a glowing pickle. Watch the webcast yourself, or read about the experiments after the jump.
If you’d like, you can watch the webcast here before finishing the post (link will open in a new window).
To kick off the latest season of the competition, the Exploratorium chose a “secret ingredient” that I don’t think you’d find on the Food Network, mostly because it’s not really an ingredient. It’s color. Yes, color, as in the properties of matter and energy, light itself.
Physicist Paul Doherty started us off with a breakdown of the visible light spectrum, which involved an actual breakdown of white light into bands of color using refracting materials like finely scratched plastic films and CDs, which are basically mirrors scratched by lasers.
After making a viewing device out of a cardboard tube and a CD with the aluminum top shaved off, Paul talked about the different wavelengths of light, using light emitting diodes to illuminate his point. He plugged a red, a green, and a blue LED bulb into a circuit in series, and showed how each required a different voltage to produce a photon, i.e., to turn on. This means that the color of the light is related to its energy. In fact, there’s a linear relationship between the energy and frequency of a wave: shorter wavelengths have higher frequencies and higher energies. Why is this relevant to everyday life? Well if you think about the frequency at which cell phone signals are produced, the wavelengths are so long (that is, they have such a low frequency) that their energy is far too low to be cancer-producing. So yak it up!
Next up was physicist Don Rathjen, who explained how polarizing materials work. The best way to think of it is as if the material (say, your sunglasses lens) is made of slits all going in one direction, like a set of blinds. Light waves can only penetrate the polarized material if they’re oriented the same way as the slit. If you were to pop out your sunglasses lenses and superimpose them at 90º, no light would go through: the “vertically” oriented waves can pass through one lens but are blocked by the horizontally oriented slits on the other. Pretty cool, but what does this have to do with color? Well if you put something like a plastic spoon between two layers of polarized material, you’ll see a certain color pattern on the spoon that corresponds to the warp pattern. Rotate one of the polarized films, and the pattern changes colors. Architects and other engineers often build their models out of plastic and then view them between polarized sheets in order to see where the stress points are. Or they can just play with the colors.
Molecular biologist and chemical engineer Julie Yoo taught us simple acid-base chemistry through color, with a little help from Kermit the Frog. Imagine if you will a series of seemingly empty beakers, and two larger beakers filled with clear fluids. Now imagine that as the “Rainbow Connection” plays, these two clear fluids are combined in ways that create yellow, green, orange, purple and red fluids, and then everything is recombined into a final clear solution. This was the day after gay marriage was passed in New York, and it was Pride weekend in SF, so the beakers were arranged to create the rainbow flag.
How did all these colors appear and disappear so delightfully? The song says it’s magic, but in fact Julie pre-loaded pH indicators into the beakers, and merely mixed different concentrations of Hydrochloric Acid (HCl) and Sodium Hydroxide (NaOH) to create solutions of varying degrees of acidity, or pH. The indicators turn the fluid a specific color in the presence of a specific basic concentration, so as soon as the base is neutralized by the acid, the color disappears. If you can find pH strips (e.g., in a litmus test kit), you can do this at home using vinegar as the acid and ammonia as the base.
Finally, Earth Scientist Eric Mueller ended the show with a bang, or rather, a glowing pickle, which is pretty much the visual equivalent of a bang. His talk was on the variety of ways in which you could excite an atom enough to produce photons of visible light. One way to give an atom energy is through heat, and what better way to do this than using a blow torch. If you put Strontium (Sr) powder on a toothpick and then put it in front of the flame, it releases a brilliant scarlet color. Copper (Cu) is green, Lithium (Li) is red, and Potassium (K) plus sugar turns an orangey-yellow.
Another way to excite atoms is through electricity, using a current to get those electrons moving. To show what Sodium (Na) looks like when thus excited, Eric hooked a super salty pickle up to a battery, completed the circuit and turned it on. Lo and behold, the pickle began to steam and glow from within! Now I’m wondering why pickle night-lights aren’t being sold everywhere…
Final thoughts: as much as I appreciated how Paul pulled his whole talk together, Julie had the best showmanship, which is why she won. If you want to know more about any of the iron science teachers, check out the Exploratorium’s Teachers Institute page. For a quick science fix and ideas for your own at-home experiments, I highly recommend watching this summer’s season of Iron Science Teacher!
Juliana Olsson is an energetic ex-San Franciscan surviving the summer heat of Nashville by drinking tasty beers, drawing (potentially) tasty eels, and writing tasty blog posts. Be sure to follow her on Twitter to experience her passions 140 characters at a time.