fun

My Extra Credit Assignment: Turn a General Chemistry Topic into a Science Museum Exhibit

When traveling, I always make a point to explore local science museums. I look for engaging exhibits that explain scientific concepts in informative and fun ways. One such exhibit at the Science Museum of Minnesota asks participants to create carbon nanotubes using foam connectors. A few friends and I used our advanced degrees to produce the example shown below (sorry for the potato quality).

The exhibit engaged people of all ages in different ways. Just behind the exhibit you can see the little guy who, moments after the picture was taken, learned all about tearing carbon nanotubes apart while deploying a rather impressive Godzilla impression.

Nanotube

Since becoming a teacher I have a new appreciation for science museum exhibits. They are a literal manifestation of Einstein’s philosophy: “If you can’t explain it to a six year old, you don’t understand it yourself.” The best exhibits make the explanation entertaining too.

So, towards the end of this spring semester when my general chemistry students requested an extra credit assignment, I knew exactly what to assign. I asked them to take one of the concepts they learned in general chemistry and create a science museum exhibit to explain it.

The assignment allowed unlimited space and budget. I was less concerned about reality and much more interested in seeing their knowledge and creativity. In the end I was blown away by their creations and would like to share a few.

Dipole-dipole Board

Dipole-dipole

The above exhibit, created by Taylor Trammell, showcases intermolecular dipole-dipole interactions. Her display contains many magnets–representing molecules–with two opposing sides, one positively charged (north pole) and one negatively charged (south pole). All of the magnets/molecules are free to rotate, except for one. Museum visitors can press a button and control the orientation of that one ‘molecule’. As it’s orientation changes, the other ‘molecules’ will reorientation to maximize dipole-dipole interactions and minimize the energy within the solvent.

A visitor could also walk up to the board with a strong bar magnet and introduce only it’s north or south pole to the magnet-filled board. That would represent the solvation of cations or anions through ion-dipole interactions. Taylor may not know it, but she found a fun way to introduce the solvent reorganization associated with Marcus Electron Transfer Theory.

Collision Theory Booth

According to the Collision Theory of Reactivity, for a chemical reaction to occur the molecules must: 1) collide, 2) have enough energy to make and break bonds, and 3) have the correct orientation when they collide. Emily Nabong demonstrates these rules of engagement through a museum exhibit that repurposes an amusement park throwing booth. Instead of milk jugs or balloons, the target is a Velcro-covered molecule. And instead of baseballs or darts, visitors throw ‘molecules’ with different geometries and Velcro coverage at the target.

If the molecule is thrown with too little momentum or too little accuracy it will not hit the board (collide). Also, if the molecule hits the board with the wrong Velcro alignment it won’t ‘stick’ (correct orientation). The ‘reaction’ will only occur if the molecule is thrown hard enough and with the right orientation.

Collision

Amorphous vs Crystalline Solids

Miranda Ave introduced an interactive “build your own solid” exhibit that demonstrates the difference between amorphous and crystalline solids. It’s comprised of two building stations. The first station offers Magnetix (below left), which have curved connectors representing bonds and metal spheres representing atoms. The second station offers Tinker Toys (below right) with only one rod length (bonds) and wood circles that connect at 90° positions (atoms).

Solids

Any structure built with the Magnetix will lack long-range order like in an amorphous solid. In contrast, a structure built with the restricted connectivity of the Tinker Toys will have a continuous, repeating pattern like those observed in crystalline solids.

Tearing apart these structures will also help demonstrate differences between amorphous and crystalline solids. Tinker Toys break apart in a ridged manner along cleavage lines while Magnetix structures break in random places.

The building stations will also be accompanied by a display with both crystalline and amorphous solids as well as an atomic picture of their structures.

Viscosity Race

Both Gabby Vega (below left) and Erum Kidwai (below right) proposed races between liquids to demonstrate differences in viscosity. They envisioned racetracks with several lanes, each labeled with a molecular structure. Museum goers would pick their ‘horse’ or lane and then watch as liquids ‘race’ down the track. Afterwards, each solution would be unveiled and the intermolecular forces dictating the viscosity and flow rates of the liquids would be explained.

Viscosity

Boyle, Lussac and Avogadro

Jessica Metzger’s museum exhibit set out to teach people about the relationship between temperature, volume, number of moles of a gas, and pressure. She proposed three different interactive stations. The first (left) contains a cylinder connected to a pressure gauge with a plunger that can be pushed or pulled. When the plunger is pushed (or pulled) and the pressure increases (or decreases), the reading on the pressure gauge will increase (or decrease) just as predicted by Boyle’s law.

The second cylinder (middle) is completely enclosed and placed on top of a heating element. When the visitors press the button a red light will turn on indicating that the chamber is being heated. As the temperature increases, the pressure will increase in accordance with Lussac’s law.

The third cylinder (right) will be taller than the other two with a lid that can move up or down without allowing gas molecules to escape. The station will be equipped with a button that, when pushed, releases compressed air into the cylinder. So, when the button is pressed, the metal lid will move up and increase the cylinder’s volume to accommodate the newly introduced gas molecules (Avogadro’s Law).

PV = nRT

Electronegativity and polarity

Carolin Hoeflich proposed an exhibit to introduce the concept of electronegativity and polarity. The exhibit includes a table with a soft foam cover and blocks representing the elements. The blocks are weighted so that electronegative elements are heavier. Museum-goers can arrange the blocks into molecular structures before dumping marbles–representing electrons–onto the table’s surface. The heavier elements will sink deeper into the foam and therefore ‘attract’ a larger number of marbles. When stepping back and looking at the structure as a whole, museum-goers will see that more marbles = more electronegativity. It’s also a fun way to visualize the dipole moment of a structure.

Electronegativity

Osmosis touch screen

Hunter Hamilton introduced a touch screen exhibit to demonstrate the principles of osmosis and osmotic pressure. Visitors will use the screen to create an environment with more or less ions (red spheres) and one of three possible ‘membrane’ options: 1) no membrane, 2) permeable to water but not ions, and 3) permeable to water and ions. Once all selections are made, the visitors presses GO and observes which direction water and ions move in their environment.

Osmosis

Le Châtelier’s Principle

Another touch screen exhibit, by Kelly Wyland, covers Le Châtelier’s Principle. Her screen displays an equilibrium with colors assigned to the reactants and products. It then asks users to predict the color change upon perturbation. After a prediction is made, the screen will show an animation that adds or removes reagents from the reaction mixture’s beaker. The color change of the solution will coincide with the concentration shifts to reach equilibrium.

LCP

Reaction Coordinate Slide

I’ve saved the largest and most interactive exhibit for last. Nathan Horvat designed an exhibit with two slides that represent an exothermic and endothermic reaction coordinate diagrams. Children (maybe adults?) would start on the platform in the middle (as reactants) and climb one of two ladders representing the activation energy to the transition state before sliding down to the landing pads (products).

The ladder/slide to the left (or right) is for an endothermic (or exothermic) reaction because the end point is higher (or lower) in energy than the starting point. One thing that I found fun about this exhibit is that, while viewing it in action, you’d likely notice more children choosing the exothermic slide because the endothermic one requires more work for less return. In a statistical fashion, the children would find the product that’s more thermodynamically favorable.

rxn coordIn closing, I want thank my students for a great semester and to share my appreciation for the students who designed these exhibits. It was a pleasure to teach them and to see them come up with such creative ideas. I hope one day, during a random science museum visit, I find one of these exhibits in action.

 

 

 

Campaign for Clear Code starts here!





I’m concerned about the software that’s installed on my electronic devices.

You should be worried as well.

Have you really considered what you are opening yourself up to every time you download a new app or install an upgrade?

Have you thought about what all those faceless software giants are doing with the code that they are busy sneaking onto your phone?

Do you have any idea what they are slipping directly into your pocket? It certainly isn’t good for you. After all its not you they care about. All that really concerns them is profit, pure and simple. They want you coming back for more, why else would they make those damn games so additive?

Screen Shot 2015-05-08 at 21.26.12

And has that code even been tested properly? They claim it has, but why then does big software continually release patches and updates?

Just stop for a minute and ask yourself this. Do you really know what you are putting on your computer when you downloaded Candy Crush? Have you ever seen the code?

Take a look at this.

“;
for(i=0;i<=20;i++)
{
f=random(3);
z=random(3);
if(tic[f][z]==’ ‘)
co-ordinates
{
tic[f][z]=’O’;
goto x;
}
else
continue;
}
x:newdisp();
d=check();
if(d==0)
user();
else
{
cout<<“

Understand it?

No, me neither.

Want to know where that snippet of code came from? Its just a small part of a computer program for tic-tac-toe. And if a game as simple as that has stuff like that in it then imagine what’s in Candy Crush, Angry Birds or even Powerpoint?

And it gets worse. Because some computer programer, in the pay of cooperate giants, writes this sort of thing before processing it into something that might not even contain recognisable words! The software companies call this ‘compiling’ and afterwards its bears no resemblance what-so-ever to the natural code.

I, for one, won’t stand for this sort of thing being foisted on me by big-software any longer.

Now is the time to take a stand.

I call for a campaign for clear code.

Basically, if a 10 year old child can’t code it then it has no place on my devices.

From this point onwards I’m reverting back to simple code that anyone can understand. I’m using nothing more than Scratch running on a nice wholesome Pi. I urge you to do the same.

And don’t even get me started on anti-virus software. Much better to share infected USB sticks around.

By May 8, 2015 3 comments fun, opinion, Uncategorized

What has Chemistry got to say?

The XKCD comics have been keeping me entertained and informed for years.

But sadly, in the latest comic, Chemistry seems rather quiet.

So how about some suggestions for the next panel, where Chemistry finds a voice?





 

By May 5, 2015 2 comments fun, Uncategorized

23 Million Times Slower than Molasses

I have the pleasure of teaching general chemistry II for the first time ever this semester. It is fun to go back and revisit concepts that I have not spent time with since taking general chemistry ~13 years ago. Our first few classes will focus on intermolecular forces (dipole-dipole, London Dispersion, etc.) and some of their macroscopic manifestations. Some examples covered in the book include surface tension, capillary action and viscosity. Searching these topics online led me to my new favorite experiment: the Pitch Drop Experiment.
Pitch Drop

In 1927, Professor Thomas Parnell started the Pitch Drop experiment in which he sought to measure the viscosity of pitch. Pitch is a general term used to describe a highly viscous solid polymer, but this material is often a complex mixture of phenols, aromatic and long chain hydrocarbons. Unfortunately, I could not find the exact composition of the pitch used in this specific experiment, but needless to say this sample does meet the description of a highly viscous material.

The experiment was initiated when Prof. Parnell heated up a sample of pitch and poured it into a conical piece of glass. The pitch was then left to sit for three years, presumably the length of time it needed to cool and completely settle into the cone shape. Immediately after the bottom of the funnel was cut open the pitch came rushing out. Just kidding. The pitch ever so slowly began dripping out of the funnel. How slowly? At a rate of approximately one drop every 10 years. In fact, the most recent drop—the 9th drop ever– fell on April 17th 2014.

The first report on this experiment was published in the European Journal of Physics in 1984. In that manuscript they calculated the pitch (2.3 x 108 Pa s) to be 230 billion times more viscous than water (1.0 x 10-3 Pa s). That means it’s more than 23 million times slower than molasses (5-10 Pa s). The longevity and creativity of this experiment won Thomas Parnell and John Mainstone (the caretaker of the experiment for more than 50 years) an Ig Nobel Prize in 2005. The experiment has also been officially included in the Guinness World Records as the world’s longest continuously running laboratory experiment.

Despite this experiment’s epicness, or maybe because of it, no one has ever been in the room to watch one of the pitch drops fall. The closest anyone has come is a time-lapse video below.


The video is unfortunately anticlimactic. It shows the 9th drop making contact with the 8th drop in the beaker. It isn’t the spectacle of a full ‘drop’ event, but don’t worry. The next occurrence is right around the corner: about 14 years away. In anticipation of this event the University of Queensland has set up three webcams and a continuously streaming live feed on a website called The Tenth Watch. Regardless of where you find yourself, you can keep a constant eye on the experiment as it progresses. And even if you miss the 10th drop, don’t worry, it’s estimated that there is enough pitch in the funnel to produce several more drops over the next 100 years.

By January 24, 2015 3 comments fun, general chemistry