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Discrepant Events Peter Shaughnessy March 2007

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1 Discrepant Events Peter Shaughnessy March 2007
Stem Seminar Discrepant Events Peter Shaughnessy March 2007 Note: click the bird to get back here. contact (if you have a question please ask it)

2 Mt Holyoke College ChemKit Program
Contact Information To borrow one of these kits please contact Edward Fitzgerald at Requirements for Borrowing Kits Kit Descriptions

3 Discrepant Events These are interest-arousing and often surprising phenomena that cause one to wonder about the science concepts being presented Activities Discrepant Events

4 Discrepant Events Main Menu
Demonstrations List Patterns and Learning Plastic Bottles Penny Eats Metal Flashy Solid Jarring Surface Tension Supercool Liquid Releases Heat Drinking Bird Methane Can Activities List

5 Activities 7 Taping the Charge 1 Vanilla Balloon 8 Polar Water
2 Alcohol and Water 3 Hot and Cold Water 9 Non Polar - Polar 10 Probing Water 4 Rates of Evaporation 5 Feeling Your Alcohol 11 Heavy Metal Tension 6 Water Mosh Pit 12 Reaction Rates Discrepant Events

6 Adding Vanilla to Balloon
Vanilla liquid begins to evaporate and form a gas.

7 Vanilla molecules are sensed outside the balloon. What does it all mean?

8 1 Vanilla in Balloon Talking Points - Liquids change to gases
Gases move from place to place Latex Balloons have unseen holes Molecules of vanilla are small Molecules have different sizes To smell something your nose has to be struck by a molecule. Activity Menu

9 2 Mixing Alcohol and Water
Observations Mixing equal volumes of water and ethanol and you get a total volume that is less than the sum of the two equal volumes. Heat is released. A gas bubble appears.

10 Talking Points of Alcohol and Water Mixture
Water is more dense than alcohol Molecules are different sizes When water and alcohol mix heat is released The heat generated vaporizes some of the liquid mixture called a solution. Activity Menu

11 3 Temperature and Molecular Motion
Translational Movement Gases Rotational Movement Gases, Liquids Vibrational Movement Gases, Liquids, Solids

12 5 sec 15 sec 35 sec 25 sec Activity Menu

13 4.Evaporation Rates Observations Talking Points
Alcohol evaporates faster in warmer rather than colder environments Talking Points Molecular attractions Average kinetic energy Comparative rates of evaporation (water)

14 Intermolecular Attractions
4 + 5 Evaporation Rates Kinetic Energy Intermolecular Attractions Relative Humidity Dynamic Equilibrium Activity Menu

15 6 Water Thermometer: The Mosh Pit

16 Temperature Scales oC = Celsius oF = Fahrenheit Space inside thermometer above the alcohol is a vacuum meaning there is nothing there! In a warmer environment the liquid alcohol expands due increased kinetic energy of the alcohol molecules taking up more space. The molecules do not get bigger Alcohol filled bulb

17 For a thermometer to work it must be struck by particles which either impart more energy or take energy from the thermometer. If the thermometer loses energy the liquid contracts and takes up less space and conversely if it gains energy the liquid inside takes up more space.

18 Water Thermometer Observations Discussion Points
Colored water rose in tube with warmer temperatures and went down with colder temperatures. Discussion Points Molecular motion at higher and lower temperatures. Molecules created a larger space around themselves be careening into others at higher temperatures. Did the molecules get bigger? Or just create more space.

19 Activity Menu

20 7 Taping the Charge Atoms Protons Electrons Positive charge +
Negative charge - Found in the nucleus Found outside the nucleus

21 Summary of Taping the Charge
A Thing Called Charge Exists There Are Two Kinds of Charge

22 Summary of taping the Charge
Like Charges Repel Negative repels Negative Positive repels Positive Electrons can be removed from atoms by rubbing or touching. Opposite Charges Attract Positive attracts Negative Negative attracts Positive Activity Menu

23 8 Visual of Demonstration of the Dipole Properties of Water
Bending Water Movie Site Activity Menu

24 9 Polar and Non-polar Liquids
Demonstrates Density differences- oil, water, Likes dissolving in likes, miscible properties Polar not dissolving in Non-Polar, immiscible

25 1.Oil 2.Oil, water 3.Oil, water, food color 3.Oil, water, food color
Activity Menu

26 10,11, Heavy Metal Causes Tension

27 What Shape Does a Water Molecule Have?

28 + + H H O =


30 Hydrogen Bond Between Molecules Only

31 Briefly Hydrogen Bonds in Water are Responsible for:
High Surface Tension of water High Boiling Point of water High Freezing Point of Water High Cohesive forces of water Ability to expand on freezing

32 Surface Tension The forces of attraction between water molecules on the surface of the liquid are greater than those below the surface.

33 Water Strider Photo by: George I. Bernard/Animals Animals
Water Strider, common name applied to slender water bug (see Bug) that is a predator on other insects. It lives on the surface of quiet waters-some species are adapted for life on faster-moving streams-and darts about with great rapidity, using the middle pair of legs as paddles and the hind pair for steering. The front pair of legs is adapted for grasping prey. Fine, dense hairs on the feet keep the insect from breaking the surface tension of the water Scientific classification: Water striders belong to the family Gerridae, of the order Hemiptera.

34 But most importantly it lets this animal do its thing!!

35 Jesus Lizard Runs on Water
Thanks to surface tension due to Hydrogen Bonds Activity Menu

36 Alka-Seltzer Reaction Rates
Observations Heat accelerates rate of chemical reaction Increasing surface area increases rate of reaction. Talking Points Increased kinetic energy increases frequency of particles hits. Increased number potential reactants increases frequency of reaction Aspirin, Sodium Bicarbonate, and Citric Acid Activity Menu

37 Plastic “PET” Bottles Heated w/o cap on Control Heated w/cap on

38 Uncapped Heated Plastic Bottle Observations
Bottles are generally smaller Height Circumference Volume Exception area where cap is screwed on Gas Bubble appeared inside bottle.

39 Explanations Polymers are stretched when made into bottles – extruded using heat and pressure. When heated in the hot water those molecules of polyethylene-terephthalate or “PET” relax and so the bottle shrinks. The gas bubble is air that has come out of the water solution. Air is not as soluble in warmer water as colder water. Discrepant events menu

40 Learning Patterns The class will be divided into two groups
Butterflies and Bluebirds Each group will be asked to do the exact same task after viewing some information for the same period of time. Prediction: One group will be significantly more successful than the other in completing the task.

41 1 5 4 7 8 2 6 3 9

42 1 4 7 = = = 2 8 5 = = = 6 9 3 = = =

43 2 6 3 1 + 3 4 3 9 7

44 1 4 7 = = = 2 8 5 = = = 6 9 3 = = =

45 1 5 4 7 8 2 6 3 9 Discrepant events menu

46 Generally there are two types of glass thermometers, alcohol and mercury filled.
Because of their hazardous affect on the human nervous system all Mercury thermometers have been removed from K-12 schools Alcohol filled red Mercury filled silver

47 Insoluble Solid/ Solvent Liquid

48 Salt crystal - NaCl Cl- Negative Chlorine ion
Na+ Positive Chlorine ion

49 Liquid/Liquid Liquid/Liquid Immiscible Miscible

50 The calcium acetate, Ca(C2H3O2)2 is soluble in the water solvent

51 The calcium acetate, Ca(C2H3O2)2 is not soluble in the ethyl alcohol solvent.

52 When the alcohol is added it becomes the major solvent by volume.
The calcium acetate precipitates out and forms a solid network. The Sterno gel is formed. Discrepant events menu

53 The Drinking Bird

54 Important Information
Vapor Pressure Is only affected by temperature changes Meaning if you reduce the volume occupied by a vapor of the liquid the vapor pressure will NOT increase. If you increase the volume occupied by a vapor of a liquid the pressure will NOT decrease. In both instances the vapor pressure will remain the same. You can not have a vapor pressure unless you have some of the liquid of the vapor present. The difference is that gas pressure is affect by both temperature changes, AND volume changes.

55 1. Water evaporates, cools head
2. Vapor pressure in head is lessened due to cooler (lower temperature) head. 3. Now the vapor pressure in butt is higher than vapor pressure in head.

56 4. Vapor pressure in butt pushes liquid up the tube
4. Vapor pressure in butt pushes liquid up the tube. Center of gravity changes and bird dips 5. Bottom tube comes out of liquid, vapor pressure in head and butt is equalized, liquid returns to butt, bird rights itself again due center of gravity change.

57 The bird will not “drink” unless the head is dipped in water or some other liquid that readily evaporates. As long as the bird has access to the liquid it will continue to drink.

58 How could you make your bird into a dipsomaniac?
Dipsomaniac: An insatiable, often periodic craving for alcoholic beverages. Click for answer: Hint: Use ethyl alcohol instead of water. It has a higher evaporation rate and cools the head more quickly as seen in the seminar. Try it and compare dip rate. Discrepant events menu

59 Getting the right mixture can be explosive.
Methane Can Getting the right mixture can be explosive.

60 The Essentials Elements of Fire
                  The interaction of the three equal sides of the fire triangle: heat, fuel and oxygen, are required for the creation and maintenance of any fire. When there is not enough heat generated to sustain the process, when the fuel is exhausted, removed, or isolated, or when oxygen supply is limited, then a side of the triangle is broken and the fire is suppressed.

61 Reaction for Burning Methane Gas
CH4(g) + 2 O2(g) --> CO2(g) + 2 H2O(g) methane oxygen carbon dioxide water gas gas gas gas Movie of Exploding Methane Can movie button upper left of page.

62 CH4(g) + 2 O2(g) --> CO2(g) + 2 H2O(g)
From the balanced Equation 1 volume methane reacts with 2 volumes of oxygen But Therefore only 1/5 of air is oxygen 1 vol CH4 X 2 vol O2/1 vol CH4 X 5 vol air/1 vol O2 = 10 vol air So the explosion occurs when the can is filled with 1 volume of methane to 10 volumes of air. Discrepant events menu

63 Observe the aluminum foil after 3 hours to note changes if any.
Submerge Penny in water on a piece of aluminum foil for a minimum of 3 hours Observe the aluminum foil after 3 hours to note changes if any. Note the holes, aluminum metal has been dissolved! Discrepant events menu

64 Wire screen top allows water to pour through
Wire screen top allows water to pour through. But when the jar is inverted the water’s surface tension and adhesive forces prevent water from pouring out.


66 Discrepant events menu

67 Supercool Sodium Acetate
Potential Energy to Kinetic Energy Heat of Crystallization Energy in Energy out idea Physical Chain Reaction

68 Sodium Acetate Web Page
Once your supersatured solution is made you simply store in it and use it year after year. All you have to do is heat it and let it cool slowly. Movie of another demo Making the original solution: The solubility of sodium acetate rises rapidly with temperature and, at 100°C, about 650g of CH3COONa will dissolve in 250ml of water. When the solution is slowly cooled without disturbance, the salt does not, however, re-precipitate and what is known as a supersaturated solution forms. Crystallization can, however, be induced by a the presence of a crystallization nucleus (crystal, glass rod, dust). Discrepant events menu

69 Mount Holyoke College ChemKit Program
1. Polymers: Children combine various concentrations of Polyvinyl Alcohol or “Elmer’s Glue All” and Sodium Borate to produce “ slime or silly putty type material”. They get to use laboratory equipment and scientific methods to explore the characteristics of polymers .

70 Continued Mt Holyoke Kits
2. Acid/Bases: Included in the kit are different ways of testing for acidity. The students use pH meters, a natural indicator (red cabbage juice), and various indicator papers, including one they produce for themselves. A section on acid rain is included, as a natural link between the topic and the student’s own environment

71 Continued Mt Holyoke Kits
3. Percent sugar in chewing gum: Students are given a piece of gum to chew. Weights are taken initially and at different intervals. Students learn weighing techniques, data collection, and presentation, while exploring solubility and weight percents. 4. Crystals: Students from crystals from a supersaturated solution of sodium acetate. They observe a heat transfer as the crystals form. This kit contains a microscope and objective lenses, allowing the students to look at crystal structures.

72 Continued Mt Holyoke Kits
5. Rocks and Minerals: This kit was developed with the assistance of the Mount Holyoke Geology department. It explores the hardness scale and the crystal structures of rocks.

73 Continued Mt Holyoke Kits
6. Chromatography: Experiments using paper chromatography to extract and separate dyes from black in pens, M&M’s and Skittles were developed. Students learn about solvents, solutes, concentrations, dyes verses lakes, and color separation.

74 Continued Mt Holyoke Kits
7. Dyes and Dying: This kit is an adaptation taken from our second semester organic chemistry labs. Students use food coloring to dye a sample of test fabric. They make predications, observe reactions to the dye on thirteen types of fabric, and draw conclusions when they get unexpected results.

75 Continued Mt Holyoke Kits
Advanced Slime Lab: This lab requires the development of the correct combination of polyvinyl alcohol with sodium borate to determine the best slime. This is for upper grades that want to discuss variables and how to come to a conclusion as to which is the best slime. Introduces percentages and variables in science experiments.

76 Continued Mt Holyoke Kits
9. Projection of a marble: This lab has been developed by the physics department of Mount Holyoke College, for high school physics lab. This lab involves velocity and ramps. Good lab for math and physics, but it is high school level.

77 Requirements The only requirement for borrowing any of these kits is that the interested teacher must pick up and return the kits to the Chemistry department. The maximum time allowed to borrow them is two weeks. Since there is no charges with borrowing the kits, we do request that you return them within that two week period so that we can restock them for others. To borrow one of these kits please contact Edward Fitzgerald at ECF/2006

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