Presentation on theme: "Discrepant Events Peter Shaughnessy March 2007"— Presentation transcript:
1Discrepant Events Peter Shaughnessy March 2007 Stem SeminarDiscrepant EventsPeter ShaughnessyMarch 2007Note: click the bird to get back here.contact (if you have a question please ask it)
2Mt Holyoke College ChemKit Program Contact InformationTo borrow one of these kits please contact Edward Fitzgerald atRequirements for Borrowing KitsKit Descriptions
3Discrepant EventsThese are interest-arousing and often surprising phenomena that cause one to wonder about the science concepts being presentedActivitiesDiscrepant Events
4Discrepant Events Main Menu Demonstrations ListPatterns and LearningPlastic BottlesPenny Eats MetalFlashy SolidJarring Surface TensionSupercool Liquid Releases HeatDrinking BirdMethane CanActivities List
5Activities 7 Taping the Charge 1 Vanilla Balloon 8 Polar Water 2 Alcohol and Water3 Hot and Cold Water9 Non Polar - Polar10 Probing Water4 Rates of Evaporation5 Feeling Your Alcohol11 Heavy Metal Tension6 Water Mosh Pit12 Reaction RatesDiscrepant Events
6Adding Vanilla to Balloon Vanilla liquid begins to evaporate and form a gas.
7Vanilla molecules are sensed outside the balloon. What does it all mean?
81 Vanilla in Balloon Talking Points - Liquids change to gases Gases move from place to placeLatex Balloons have unseen holesMolecules of vanilla are smallMolecules have different sizesTo smell something your nose has to be struck by a molecule.Activity Menu
92 Mixing Alcohol and Water ObservationsMixing 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.
10Talking Points of Alcohol and Water Mixture Water is more dense than alcoholMolecules are different sizesWhen water and alcohol mix heat is releasedThe heat generated vaporizes some of the liquid mixture called a solution.Activity Menu
113 Temperature and Molecular Motion Translational MovementGasesRotational MovementGases, LiquidsVibrational MovementGases, Liquids, Solids
16Temperature ScalesoC = CelsiusoF = FahrenheitSpace 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 biggerAlcohol filled bulb
17For 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.
18Water Thermometer Observations Discussion Points Colored water rose in tube with warmer temperatures and went down with colder temperatures.Discussion PointsMolecular 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.
207 Taping the Charge Atoms Protons Electrons Positive charge + Negative charge -Found in the nucleusFound outside the nucleus
21Summary of Taping the Charge A Thing Called Charge ExistsThere Are Two Kinds of Charge
22Summary of taping the Charge Like Charges RepelNegative repels NegativePositive repels PositiveElectrons can be removed from atoms by rubbing or touching.Opposite Charges AttractPositive attracts NegativeNegative attracts PositiveActivity Menu
238 Visual of Demonstration of the Dipole Properties of Water Bending Water Movie SiteActivity Menu
249 Polar and Non-polar Liquids DemonstratesDensity differences- oil, water,Likes dissolving in likes, miscible propertiesPolar not dissolving in Non-Polar, immiscible
251.Oil 2.Oil, water 3.Oil, water, food color 3.Oil, water, food color Activity Menu
31Briefly Hydrogen Bonds in Water are Responsible for: High Surface Tension of waterHigh Boiling Point of waterHigh Freezing Point of WaterHigh Cohesive forces of waterAbility to expand on freezing
32Surface TensionThe forces of attraction between water molecules on the surface of the liquid are greater than those below the surface.
33Water 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 waterScientific classification: Water striders belong to the family Gerridae, of the order Hemiptera.
34But most importantly it lets this animal do its thing!!
35Jesus Lizard Runs on Water Thanks to surface tension due to Hydrogen BondsActivity Menu
36Alka-Seltzer Reaction Rates ObservationsHeat accelerates rate of chemical reactionIncreasing surface area increases rate of reaction.Talking PointsIncreased kinetic energy increases frequency of particles hits.Increased number potential reactants increases frequency of reactionAspirin, Sodium Bicarbonate, and Citric AcidActivity Menu
37Plastic “PET” BottlesHeated w/o cap onControlHeated w/cap on
38Uncapped Heated Plastic Bottle Observations Bottles are generally smallerHeightCircumferenceVolumeException area where cap is screwed onGas Bubble appeared inside bottle.
39ExplanationsPolymers 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
40Learning Patterns The class will be divided into two groups Butterflies and BluebirdsEach 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.
46Generally 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 schoolsAlcohol filled redMercury filled silver
54Important Information Vapor PressureIs only affected by temperature changesMeaning 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.
551. 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.
564. 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 dips5. 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.
57The 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.
58How 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
59Getting the right mixture can be explosive. Methane CanGetting the right mixture can be explosive.
60The 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.
61Reaction for Burning Methane Gas CH4(g) + 2 O2(g) --> CO2(g) + 2 H2O(g)methane oxygen carbon dioxide watergas gas gas gasMovie of Exploding Methane Can movie button upper left of page.
62CH4(g) + 2 O2(g) --> CO2(g) + 2 H2O(g) From the balanced Equation1 volume methane reacts with 2 volumes of oxygenButThereforeonly 1/5 of air is oxygen1 vol CH4 X 2 vol O2/1 vol CH4 X 5 vol air/1 vol O2 = 10 vol airSo the explosion occurs when the can is filled with 1 volume of methane to 10 volumes of air.Discrepant events menu
63Observe 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 hoursObserve the aluminum foil after 3 hours to note changes if any.Note the holes, aluminum metal has been dissolved!Discrepant events menu
64Wire 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.
67Supercool Sodium Acetate Potential Energy to Kinetic EnergyHeat of CrystallizationEnergy in Energy out ideaPhysical Chain Reaction
68Sodium 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 demoMaking 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
69Mount 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.
70Continued 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
71Continued 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.
72Continued 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.
73Continued 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.
74Continued 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.
75Continued 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.
76Continued 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.
77RequirementsThe 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 atECF/2006