Visualizing Catalysis, and chemical change generally; bringing chemistry closer to kids
We do a variety of interactive chemistry and catalytic related demonstrations with kids age 5-10, together with their parents or grandparents. We have an excellent audience, an average of 10 kids per show and we do four shows in a Saturday afternoon, all taking place at Wonderlab, a kids science museum in Bloomington, IN. We build up interest in our demos by being highly interactive with the kids, asking them what they predict will happen before showing the demo, then analyzing what they saw.
Methanol reactor flask, and Pt wire coil at end of Cu catalyst holder: fuel cell building blocks. (July, 2016)
Watching Nick Maciulis’s catalysis on glowing Pt wire.
We show heterogeneous catalysis of air oxidation of methanol at the surface of a Pt wire, suspended above a puddle of liquid methanol. The wire glows brighter as a result of heat of reaction, then finally reaches the MeOH vapor flash point, causing a minor explosion, whereupon the formed CO2 (greenhouse gas!) forces most of the O2 out of the Erlenmeyer flask, quenching the reaction and cooling the Pt wire. The Pt grows dark, then glows warmer as O2 returns in the narrow Erlenmeyer opening, and finally glows red, then white, and explodes again, quenching and then restarting the cycle. We ask about the fog on the flask interior walls, about why the phenomenon oscillates, about other phenomena they know which oscillate (seasons, moon, sun, daily temperature….. ) and the origin of these in nature. We ask about fuel, other kinds of fuel, about CO2 and its greenhouse implications (10 year olds already know this!), and then we invite them to move to another demo, on reaction of dichromate with H2O2 to liberate O2 and make Cr(III), via a visibly dark CrO5 intermediate.
Sasha Polezhaev showing production of dark blue CrO5, on the way to O2 evolution.
Sasha preparing dichromate solution for O2 evolution; we hope that Sesame street character will grow up to become a leading scientist.
Oxygen evolution is done in a two phase system with aqueous dichromate as bottom layer and Et2O as top layer (“Why is yellow orange dichromate solution on bottom, not the top?” “Do you expect the two liquids will mix when I stir?” “Why don’t the two liquids mix together?” “Do you know of other liquids that do not mix? Why don’t they finally mix?“). This reaction actually goes via a chromium intermediate which complexes Et2O, so is slightly, VISIBLY soluble in the ether layer. The ether layer also helps visualize the O2 bubbling up from the more concentrated dark blue which snakes downwards through the orange dichromate aqueous phase. This discussion links, conceptually, to the O2 consumed in the methanol oxidation. We ask about colors, we talk about “chrome” bumpers on old cars, ….and on the plumbing at our demo table. Younger kids and older kids give very different answers to our questions but we encourage and explain answers at both degrees of sophistication. We reach kids of all ages, and their parents and grandparents. The kids become increasingly interactive, and they gain courage to give their own opinions, about fuel (they think about barbeque grills and campfires!), about bad gases and good gases, about how plants (trees, algae) consume bad CO2, and give us back a good gas, O2. Our research group members learn to react spontaneously and constructively to the sometimes off-target answers from kids, but nevertheless embrace such a “teachable moment.” We emphasize real-world application or at least examples relevant to our demos: “If glowing Pt is like your fireplace at home, which do you prefer to use to fuel the heat, firewood or liquid methanol (the latter used in hunters’ and ice fisherman’s sock warmer devices, and, most generally, in the methanol fuel cell!).” We talk about Pt contained in the catalytic converter under the car that transported them to Wonderlab. Group members go away from such an afternoon really inspired by what they CAN do to publicize their science!
Using the noodle to simulate AFM and STM to “image” objects. The stegosaurus is especially challenging to image!
Even exotic techniques can be illustrated: the dependence of our research on AFM and STM to “image” our surfaces for heterogeneous catalysis is illustrated by using a swimming pool “noodle” (flexible plastic tube 2 meters long) to sense the shape of an object put in front of them while they are blindfolded, or feel, with their hand, concealed inside a box to discern the pattern of gum drops glued to the box interior for their pattern: square, diamond, hexagonal, etc. Wonderlab is a huge asset to our effort, and we “compete” with nearby NSF outreach sponsored exhibits at Wonderlab on brain imaging via 19F tomography, and another on MRI imaging of body parts, with Gd image enhancement….sophisticated science for southern Indiana kids! Parents and grandparents who bring their kids to Wonderlab were interviewed, thinking that the adults would all be scientists. This was not at all true: they simply value entertaining their kids at a highly interactive facility. This is thus an ideal family audience to create informed opinions about science touching their lives.
Nick Maciulis getting kids to remark that Pt, a catalyst, is also in mom’s jewelry; parents and even grandpa (far left) enjoy the discussion.
The youngest guest at Nick Maciulis’ methanol oxidation catalysis demo; it’s never too early to inspire a budding scientist.
We have added a very effective demonstration of the photoinduced reduction of the purple dye thionin by acidic aqueous Fe(2+), which can be done and visualized on an overhead projector, which also serves as the source of photons. We get the kids to talk about photochemical reactions in everyday life (tanning, fading of garden furniture and painted walls…). Use of carefully selected masks to shield part of the solution from irradiation allows creation of layered volumes and shaped designs (star, lightning bolts, etc) in a solution. The reduced thionin and co-product Fe(3+) back-react, so under irradiation, the system reaches a photostationary state, which is reversed within less than a minute following shielding of the light source, to return to dark purple. This allows us to ask the kids about everyday life examples of “reversibility,” and also to illustrate storage of solar energy as high energy chemical compounds. We then talk about how stored chemical energy can be triggered to release “on demand,” and tell them that they will now do THAT experiment themselves, with the energy release detected by emission of light. We then hand every child a light stick, a flexible plastic tube containing a crushable glass tube which, when flexed, combines reagents to produce the cyclic dimer of CO2, which reacts with various dyes attached to the inner wall of the flexible tube, to fluoresce distinctive colors. The flexible tube then can be formed into a necklace and every kid walks home with a souvenir of the demo activity (see photos). It is a special pleasure that the actual energy transfer molecule used here is related to the greenhouse gas CO2, and not many chemists are aware of the cyclic CO2 dimer.
Group member Julie Seo with fluorescent lightstick necklace of a young scientist.