07 September 1999: Pat Riley (Lincoln Park HS)
asked us to differentiate between compounds, elements and mixtures, using various combinations of nuts, bolts and washers, sealed inside culture dishes. Groups of us passed around the dishes and filled out an answer sheet as to which category(ies) a particular dish belonged. Then the groups were challenged to separate 3 different mixtures in cups, using beakers, paper towel, funnel and magnet. And she gave us yet another problem, to separate mixtures of chunks of marble and a copper compound. We were furnished tweezers, and based the separation on color and shape of the chunks. Is there another way?

26 October 1999: Pat Riley (Lincoln Park HS)
passed out a pattern to cut out cloth and sew pieces together and make a stuffed mole animal. She showed us several completed "moles," a silvery one being a "mole of silver," a gold one being a "mole of gold," etc. Chemistry with as sense of humor! She held up a small "mole," and suddenly "tore" it in half! (Velcro™ held it together). "What is this?" she asked. "Half a mole!" was the answer! And Earl Zwicker (IIT Physics) showed us a small silvery cylinder which weighed about 27 grams. An actual mole of Aluminum.

09 November 1999: Ben Butler (L Ward School)
wrote: A Scientific Method - OPHEC. Observation, Problem, Hypothesis, Experiment, Conclusion. Then he gave us a problem: Which plastic wrap keeps food driest? H - involves selection of several plastic wraps (Jewel, Handiwrap™, etc). E - Use folded paper towels inside plastic wrap, twisted tightly and held with rubber band. Drop into large plastic bag with water, check after a day or so. O - see paper towels are driest. C - conclude - answer to Problem. (HandiWrap™ was best!). Thanks, Ben!

26 September 2000: Zoris Soderberg (Webster School)
gave us her creed:

25 September 2001: Lee Slick (Morgan Park)
Lee started up a rebus, actually a series of them, each being an element:  Sodium, Carbon, etc.  By the way, a rebus is a set of pictographs, symbols, and operations to represent a word or phrase.  For example

"picture of needle and thread" + D + "picture of a pack of gum" - G =  SODIUM

Get it?? A terrific way to engage kids as they learn about the chemical elements.

25 September 2001: Therese Donatello (St Edwards School)
Therese presented the following three exercises.

1. She simulated rock layers in the earth's crust using layers of paper, showing how they are deformed and changed under stress [force per unit area]. She took three sheets of construction paper (rectangles of size about  5 ´ 10 inches; or 12 ´ 25 cm), each of a different color, and made slight 1 inch or 2 cm cuts across the two long sides of each sheet at the same place. She held the stacks of paper by the short sides with both hands, and pushed [either equally or unequally] with her hands to show how the layers were deformed.

   Then she pulled on the papers, the cuts making it easier for the paper to start tearing.  We investigated finding how to tear the paper most easily; that is, was it better to pull slowly, quickly, from the sides, from opposite ends, etc.  If the tearing is uneven and not the same for each layer, it may be because of the different compositions of paper in the various layers.  This illustrates how movements in the earth's crust can lead to earthquakes.  Very nice, Therese!

2. Each group received one large and one small paper clip.  We looked at the paper clips "edge on"; they were originally flat.  Then we repeated this observation after clipping on 2, 5, 20, and 50 pieces of paper.  As the paper stacks got larger, we could see that the paper clips got progressively more deformed, and their appearances changed as viewed edge on; they were no longer flat.

   The paper clips were made of different materials, such as metal or plastic. We noted that the smaller clips bent more than the larger ones, and even with clips of the same size there was variation in bending because of the different material composition. Also, with smaller stacks of paper the clips stretched, but rebounded when the paper was removed. By contrast, with sufficiently large stacks of paper the paper clips would stay deformed after the paper was removed. Evidently, the clips had reached their elastic limit, and their shape was irreversibly altered.

3. Therese next passed out balloons and rubber bands, and we measured their relaxed length with rulers.  We then stretched the balloon / rubber band to 1.5 times its relaxed length, let it go, and re-measured its new relaxed length.  We continued the process, stretching by 2 times its original length, 2.5 times its original length, etc.  Here are the measurements for one of the balloons:
   

   Stretch Factor	Measured Length
   1 ´	9.5 cm
   1.5 ´	9.5 cm
   2.0 ´	9.5 cm
   2.5 ´	9.5 cm
   3 ´	9.5 cm
   Elastic Limit
   4 ´	9.7 cm
   5 ´	10.0 cm

   Note that the elastic limit is reached at somewhere between 3 and 4 times the original relaxed length of the balloon. The rubber band was somewhat more elastic, or more resistant to permanent deformation, than the balloon. The distinct behavior of different materials, or different arrangements configurations of similar materials, is interesting and significant.
   

04 December 2001: Tyrethis Penrice (Oak Park Elementary) Behavior of Matter: Handouts on Adhesion and Cohesion
Tyrethis led our discussion of these questions:

1. Q: What happens when drops of water are placed on talcum powder.
   A: We suggested "beading up", absorption, and "clumping" of talcum powder
   
2. Q: What happens to the surface of water sprinkled with pepper when detergent is dropped in?
   A: We thought the pepper grains would move away from the detergent layer.

1. Drops did form beads which, after a few minutes, had a skin of talcum powder on them. The beads formed only where talc was fairly thickly spread on the paper. We may have been seeing cohesion of H₂O to H₂O, talc to talc, or adhesion of talc to H₂O---or perhaps all of them. We would not expect the talc to H₂O interaction to be present, since beading occurs.
   
2. Initially the pepper floats uniformly spread on the surface of the H₂O .  The addition of detergent initially causes the pepper grains to move away from one another suddenly (similar to "like charge" repulsion?) and then to sink below the surface (loss of surface tension).
   
3. In a third activity a glass was filled to the top with H₂O so that there was a "surface bulge" over the edge of the glass.  A cork was then floated on the surface.  The surface tension kept the cork near the center of the glass, far away from the edges.

02 April 2002: Erma Lee (Williams School) -- Geochemistry: Movement of Ground Water
Erma led us through an investigation of the movement of ground water through materials of various porosities. She added water to cups of equal size, filled with sand and marbles, respectively.  To our surprise, each cup held about half of its volume in water.  We had expected to be able to put less water in the cup filled with sand, because the grains of sand pack more tightly together, resulting in smaller interstitial spaces between the grains of sand than between marbles.  However, the number of interstitial spaces between grains of sand is much greater than for marbles, so that total interstitial space is about the same for both.  With an identical cup with fine (porous) sawdust, we were able to add one full cup of water.  This we attributed to the absorbance (permeability) of the sawdust compared to near zero absorbance for sand grains and marbles.

At Ken's suggestion, we added a cup of sand to a cup half-filled with water (reverse order to that done above), to see if the results would be the same as our previous experiment with sand.  They weren't, in that more sand could be mixed in when we added sand to water!  (There was some concern as to whether these experiments were done with sufficient care the first time, since we might have been able to mix in "more sand" if we had tried.)

Ken Schug explained that, if both sand grains and marbles consist of spheres at the closest possible packing, the fraction of interstitial volume should be independent of the sizes of the spheres, as we observed in the first part.  It seems quite reasonable for the sand grains to be essentially spherical.  Fascinating, Erma!

23 April 2002: Ann Parham and Winifred Malvin (Carver Primary School) -- The Bottle Volcano; The Mysterious Balloon; Density
Ann and Winifred put a bewildering array of plastic bottles, stains, dyes, and such on the front desk so that we could all make a Bottle Volcano!  They handed out information obtained from  The Know How Book of Experiments by Heather Amery: [EMC Paradigm, September 1978];  ISBN: 088436531X

We filled two identical bottles with hot and cold water, respectively, and then put the bottle holding (colored) hot water on the bottom, and the inverted cold water bottle on top, with a piece of thin cardboard separating them.  We carefully removed the cardboard without spilling water, and noticed that the colored hot water (less dense) flowed into the upper bottle to the top.  We concluded that the less dense hot water was "floating" on  a sea of cold, less dense water.  Ann did the experiment with very hot water [obtained from a coffee pot] and quite cold water, and we observed that the Volcano works best when there is a great temperature difference in the two components.  We discussed the similarity in this phenomenon and the formation of thunderstorms during warm periods, as warm air at the surface of the earth rises into the region of denser, colder air aloft.

Then Winifred did the Mysterious Balloon demonstration, in which a wooden skewer [shish kabob stick] is pushed through the top of balloon, and then down through the bottom.  Winifred noted that the balloon acts like a white blood cell that  can engulf a foreign object [skewer] without rupturing.  The latex molecules in the balloon apparently form a tight seal around the skewer, analogously to the way in which the fluid membrane of a cell engulfs a foreign object (virus, bacterium, etc) without rupturing. 

Then Winifred had us prepare three [100 ml] samples -- one of clear water, one of water with 1 teaspoon (10 g) of dissolved salt, and one of water with 2 teaspoons of dissolved salt.  The saline solutions were dyed to make them green and red, respectively.  We each took a clear drinking straw and placed it upright by sticking one end in a piece of modeling clay, which also sealed that end.  We carefully (slowly!) added about 1 ml aliquots of each solution of the straw with eye droppers in a "random order"; in addition the three solutions were "stacked" in the straw in order of decreasing density; that is, with the most dense at the bottom, etc.  The most dense solution contained 2 teaspoons of dissolved salt, and the least dense had no salt at all. The color pattern made it easy to distinguish the three layers.  If done with sufficient care, one could make a more dense solution layer lie underneath a less dense layer, if the less dense layer is slowly put in first.  Very stimulating, Winifred and Ann.

25 February 2003: Ken Schug [IIT Chemistry]      Three Presentations from His Bag of Tricks

1. Ken took a dollar bill  from his hapless victim, Ben Stark, dipped it into an unspecified liquid, held it in his hand, and lit it with a match.  A big flame arose, which Ken blew out by shaking the bill. Ben's bill survived the ordeal intact.  The liquid, which consisted principally of ethyl alcohol, smelled strongly of peppermint.  Then Ken performed the same experiment with his own finger.  He dipped the finger into the liquid, lit it, and then shook out the flame.  Why didn't the bill or his finger get burned?  It was our consensus that alcohol burns at a lower temperature than the ignition temperature of paper --- Fahrenheit 451, according to sci-fi writer/guru Ray Bradbury: http://www.classicnote.com/ClassicNotes/Titles/fahrenheit/about.html --- or of fingers, for that matter!
   
2. Ken brought out a jar of a clear liquid with dark blobs at the bottom of the jar.  Ken had evidently been trying to make his very own Lava Lamp!  How does a Lava Lamp work?  There is a light bulb just underneath, which generates both light and heat when turned on.  The idea is to have a semi-solid material (wax?) --- one that is not soluble in water ---- which expands with temperature at a greater rate than the bulk liquid.  The semi-solid mass gets near the light /heat source, becomes warmer, expands, and then rises to the cooler region in the vessel, where it becomes more dense, and sinks.
   
   We then talked about how the fact that the density of water varies with temperature is important in biology --- particularly the fact that water has a maximum density at 4° C.  As a consequence of this fact, no part of a body of water [lake or pond] can sustain a temperature below 4° C unless and until temperature of the entire body of water is reduced to 4° C.  Further cooling at the top results in a temperature inversion, at which the top layers of water are cooler than those near the bottom, and an ice layer forms on the top of the body of water.  Fish and other organisms can survive in the cold, but unfrozen water beneath the ice layer. 
   
3. Ken initiated a discussion of proteins by asking the following questions:
   
   • What are proteins and where are they found? [muscles, enzymes, etc]
   • What are amino acids? [They are the sub-units or building blocks that are assembled to make proteins --- all proteins on earth are made from only 20 different amino acids.]
   There is a myriad of ways of polymerizing these 20 amino acids in distinct combinations to form a virtually endless variety of protein structures. Proteins are "biological polymers", in the same sense that plastics are "non-biological polymers".

   Ken illustrated the process of polymerization using starch, which is a polymer consisting of units of glucose.  There are various enzymes that de-polymerize starch, converting it into glucose, so that it can be digested.  Ken pointed out that cellulose is also a polymer with glucose units, but the glucose units are connected differently in starch and in cellulose.  We cannot digest cellulose, although certain organisms (e.g. certain fungi and bacteria) can digest it.

   How many different proteins be assembled from just 20 different amino acids?  Ken illustrated the combinatorial possibilities using hookable beads of  5 different colors.  For ordered polymers consisting of 10 units --- dekamers, or whatever --- there are 10⁵ different color combinations.  One may assemble 4 beads of different colors into 24 = 4 ´  3 ´  2 ´  1 distinct ways, whereas 5 beads of different colors can be assembled in 120 distinct ways.  For protein pentamers --- or 5 unit polymers --- there are 20⁵ = 3,200,000 different possibilities.  Real polymers consist of around 100 to 1000 amino acids, so that there is a virtually limitless set of possibilities --- 20¹⁰⁰ is comparable to the number of hydrogen atoms in the universe!

We continued to discuss topics such as protein structure, Recombinant DNA, and genetic engineering.  In particular, we discussed the number of different proteins present in a given organism.  That number can be as small as 484 in the simplest bacterium, whereas in humans there are 35,000 - 40,000 different types of protein.

New tricks from old dogs came forth in abundance! Great job, Ken!

07 October 2003: Estellvenia Sanders [Chicago Vocational HS]       Matter (and differences in materials) Handout:
Estellvenia began by putting the following list of terms on the board:

Estellvenia then put a rusty paper clip into a small beaker, covering it with a layer of drain cleaner [The Works™]. Will the paper clip eventually be cleaned this way?? We will check it at the next class meeting.

Good stuff, Estellvenia.

23 March 2004: Terry Donatello [ST Edwards: Elmwood Park]         Identification and Chemical Properties of Minerals
Terry showed us how to use 3D "Viewmaster" Glasses to view paired stereoptic pictures of crystals. She also had molecular models for various crystal structures.  We compared the pictures of the crystals to the models that Terry's students had made with wooden sticks, toothpicks, twist ties, pipe cleaners, and wire. The key parameters included the number of axes, their relative lengths, and the angles between them.

We also looked at stereo pictures of various biological macromolecules (proteins) that were in a Biochemistry textbook.  Terry then  passed out several baggies containing small pieces of minerals (about 2 cm in size).  We ran the following tests in our attempts to identify them. 

• We started by doing a scratch test to determine the hardness of the samples, first using our fingernails, a copper wire, and then a steel nail.
• Then we made a streak test, which consists of rubbing the mineral in question on a streak plate -- a small, flat piece of unglazed porcelain. We noted the color of the streak or powder left by the minerals.
• Finally, we did a fizz test on the minerals, to see whether they contained carbonate compounds.  We put one drop of molar Hydrochloric Acid (HCl) on the mineral.  Any mineral containing carbonates would begin to fizz, because of the chemical reaction #(++) CO₃ + 2 HCl ® H₂CO₃ + #(++)Cl₂
  H₂CO₃ ® H₂O + CO₂ (the fizz)

Finally, Terry revealed the identities of the various minerals.  

For a set of crystal images from Alan Guisewite's Mineral Collection see the website http://www-2.cs.cmu.edu/~adg/adg-piimages.html.

Sherlock Holmes, Super Chemist! Very good, Terry!

14 September 2004: Pat Riley (Lincoln Park HS)
gave the first presentation of the year. Pat's first part was a nifty way to explain density. It involved three identical dark amber bottles (with lids), one of which was filled with cotton, one with water, and one with iron filings. Although all three looked identical from the outside (and had identical volumes), lifting (by Ed Scanlon) clearly showed that the masses (and thus the densities) were different, in both cases increasing in the order "cotton", "water", "iron filings".

Pat then showed a neat way to demonstrate the large heat capacity of water; this was done with ordinary (waxed paper) Dixie cups. Pat first showed that a Dixie cup will start burning easily when lighted with a match (we showed this first for the rim of the cup and later for the bottom; it works both ways). When the cup was filled with water, however, the lighted match would not set the cup on fire when held beneath the bottom of the cup; the water absorbed so much of the heat from the burning match (1 calorie/gm/degree C--the "specific heat" of water) that the paper could not reach a high enough temperature to ignite. The cup with the water did accumulate soot from the burning match on its bottom, which looked superficially like the result of burning, but closer examination showed that the cup with water did not burn. Excellent, Pat!

08 March 2005: Chris Etapa [Gunsaulas Academy]           Some Fabulous Information
Chris just finished a program at UIC (inherited from Northwestern) called "Get a Grip". UIC sends engineering graduate students into a class (from 5th to 10th grades) and helps the students design and build a prosthetic arm (for poor countries; ie, inexpensively). A kit is supplied to the class with common materials (PVC pipe, clamps, rope, etc.); arms are designed for several different tasks (eg, carrying water, picking up small objects).

UICis looking for more partner schools; for now, UIC funds the program directly. Chris will bring us pictures/examples to share next time.

Chris also shared information about another project in which she is involved (sponsored by the World Food Organization) in which plants are grown in "grow boxes" and classes are partnered with classes in other parts of the US and other parts of the world to share their experiences. Each box is about $74 (shipping included) and works for three years. Various vegetables can be grown in the grow boxes.

10 May 2005: Barbara Lorde [Attucks School]                           Dancing Spaghetti
The presentation is based upon the web page Dancing Spaghetti: http://www.science-house.org/CO2/activities/co2/spaghetti.html on the website of  the NSF Science & Technology Center for Environmentally Responsible Solvents and Processes [CERSP], which she passed around the room. Basically, the addition of vinegar to baking soda (the classic elementary school chemical reaction) produces bubbles of carbon dioxide.  When small pieces of spaghetti are mixed with baking soda, and vinegar is then added, the spaghetti pieces begin to dance. This "dancing spaghetti" is a visual assay of the chemical reaction:

Then Barbara described discussions with her students about careers that require the study of science in school. For example, chemistry is directly relevant to careers in medicine, pharmacy, research, forensics, cooking, the food industry, hazardous material removal, and many others.

Barbara also showed us how to make fingerprints by shading a small piece of paper with a soft pencil, then putting the finger tip in the shaded area to pick up the pencil mark, and then transferring it (as a fingerprint) to a piece of clear tape (which can then be taped to a second piece of paper, producing a permanent preparation of the fingerprint). Barbara does a similar exercise with lip prints using lipstick as the "color" to transfer the print to a piece of paper (to produce a permanent record). Details appear in the attached sheets (from http://www.chem4kids.com for the fingerprints and http://www.lawrencehallofscience.org for the lip prints).

Good ideas! Thanks, Barbara.

02 May 2006: Walter Kondratko (Fenger HS, chemistry)                     Stuff From Class
Walter showed us a crystal that was grown in his class; the kit can be ordered on the website  http://scientificsonline.com/product.asp?pn=3081666&cmss=grow+crystal. Walter then showed us a Crookes tube  http://home.att.net/~numericana/arms/crookes.htm. A current was passed through the tube,  using a high voltage source (5000 Volts -- without the ballast circuit usually found in house fluorescent lights). A fluorescent coated strip mounted vertically within the tube allowed us to see the path of a  beam of electrons through the tube. Walter showed that the beam could be deflected up or down with a horseshoe magnet. Then he showed us a ball and stick model of an amino acid to illustrate chirality/enantiaomers [http://www.brynmawr.edu/Acads/Chem/mnerzsto/PolarimetryExercise.htm], and showed that they were mirror image isomers, which are not geometrically identical. These amino acids produce optical rotation.  The plane of polarization of light rotates  in different directions for dextrorotary (right-rotating) and levorotary (left-rotating) compounds.. For details see Stereochemistry Tutorial:  http://facultystaff.vwc.edu/~jeaster/courseinfo/Tutorials/stereochemistryl.html.
Beautiful phenomena -- quite illuminating! Thanks Walter.