Presentation on theme: "Stem Seminar Discrepant Events Peter Shaughnessy March 2007 contact (if you have a question please ask it) Note: click."— Presentation transcript:
Stem Seminar Discrepant Events Peter Shaughnessy March contact (if you have a question please ask it) Note: click the bird to get back here.
Mt Holyoke College ChemKit Program –Contact Information –To borrow one of these kits please contact Edward Fitzgerald at –Requirements for Borrowing KitsRequirements for Borrowing –Kit DescriptionsKit Descriptions
Discrepant Events These are interest- arousing and often surprising phenomena that cause one to wonder about the science concepts being presented ActivitiesDiscrepant Events
Discrepant Events Main Menu Demonstrations List Patterns and Learning Plastic Bottles Flashy Solid Methane Can Jarring Surface Tension Penny Eats Metal Drinking Bird Supercool Liquid Releases Heat ActivitiesActivities List
Activities 1 Vanilla Balloon 2 Alcohol and Water 3 Hot and Cold Water 4 Rates of Evaporation 5 Feeling Your Alcohol 6 Water Mosh Pit 7 Taping the Charge 8 Polar Water 9 Non Polar - Polar 10 Probing Water 11 Heavy Metal Tension 12 Reaction Rates Discrepant Events
Adding Vanilla to Balloon Vanilla liquid begins to evaporate and form a gas.
Vanilla molecules are sensed outside the balloon. What does it all mean?
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
2 Mixing Alcohol and WaterMixing 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.
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
3 Temperature and Molecular MotionTemperature and Molecular Motion Translational Movement Rotational Movement Vibrational Movement Gases Gases, Liquids Gases, Liquids, Solids
5 sec 25 sec 35 sec 15 sec Activity Menu
4.Evaporation Rates Observations –Alcohol evaporates faster in warmer rather than colder environments Talking Points –Molecular attractions –Average kinetic energy –Comparative rates of evaporation (water)
4 + 5 Evaporation RatesEvaporation Rates Intermolecular Attractions Kinetic Energy Relative Humidity Dynamic Equilibrium Activity Menu
6 Water Thermometer: The Mosh Pit
Alcohol filled bulb Temperature Scales o C = Celsius o F = Fahrenheit 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 Space inside thermometer above the alcohol is a vacuum meaning there is nothing there!
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.
Water Thermometer Observations –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.
7 Taping the Charge Atoms ProtonsElectrons Positive charge + Negative charge - Found in the nucleus Found outside the nucleus
Summary of Taping the Charge A Thing Called Charge Exists There Are Two Kinds of Charge
Summary of taping the Charge Electrons can be removed from atoms by rubbing or touching. Like Charges Repel Negative repels Negative Positive repels Positive Opposite Charges Attract Positive attracts Negative Negative attracts Positive Activity Menu
8 Visual of Demonstration of the Dipole Properties of Water Bending Water Movie Site Activity Menu
9 Polar and Non-polar Liquids Demonstrates –Density differences- oil, water, –Likes dissolving in likes, miscible properties –Polar not dissolving in Non-Polar, immiscible
1.Oil2.Oil, water 3.Oil, water, food color Activity Menu
10,11, Heavy Metal Causes Tension
What Shape Does a Water Molecule Have? H H O
H H O + + =
Between Molecules Only
Briefly Hydrogen Bonds in Water are Responsible for: High Boiling Point of water High Freezing Point of Water High Surface Tension of water High Cohesive forces of water Ability to expand on freezing
Surface Tension The forces of attraction between water molecules on the surface of the liquid are greater than those below the surface.
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.
But most importantly it lets this animal do its thing!!
Jesus Lizard Runs on Water Thanks to surface tension due to Hydrogen Bonds Activity Menu
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
Heated w/o cap onControlHeated w/cap on Plastic PET Bottles
Uncapped Heated Plastic Bottle Observations Bottles are generally smaller –Height –Circumference –Volume –Exception area where cap is screwed on Gas Bubble appeared inside bottle.
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
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.
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Discrepant events menu
Mercury filled silver Alcohol filled red 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
Salt crystal - NaCl Cl- Negative Chlorine ion Na+ Positive Chlorine ion
Miscible Immiscible Liquid/Liquid
The calcium acetate, Ca(C 2 H 3 O 2 ) 2 is soluble in the water solvent
The calcium acetate, Ca(C 2 H 3 O 2 ) 2 is not soluble in the ethyl alcohol solvent.
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
The Drinking Bird
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.
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.
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.
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.
How could you make your bird into a dipsomaniac? Dipsomaniac: An insatiable, often periodic craving for alcoholic beverages. Discrepant events menu 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.
Methane Can Getting the right mixture can be explosive.
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. The Essentials Elements of Fire
Movie of Exploding Methane Can Movie of Exploding Methane Can movie button upper left of page. CH 4(g) + 2 O 2(g) --> CO 2(g) + 2 H 2 O (g) methane oxygen carbon dioxide water gas gas Reaction for Burning Methane Gas
From the balanced Equation CH 4(g) + 2 O 2(g) --> CO 2(g) + 2 H 2 O (g) 1 volume methane reacts with 2 volumes of oxygen only 1/5 of air is oxygen Therefore So the explosion occurs when the can is filled with 1 volume of methane to 10 volumes of air. 1 vol CH 4 X 2 vol O 2 /1 vol CH 4 X 5 vol air/1 vol O 2 = 10 vol air But Discrepant events menu
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. Discrepant events menu Note the holes, aluminum metal has been dissolved!
Wire screen top allows water to pour through. But when the jar is inverted the waters surface tension and adhesive forces prevent water from pouring out.
Discrepant events menu
Supercool Sodium Acetate Potential Energy to Kinetic Energy Heat of Crystallization Energy in Energy out idea Physical Chain Reaction
Sodium Acetate Sodium Acetate Web Page Discrepant events menu 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. 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). Movie of another demo
.... Mount Holyoke College ChemKit Program 1. Polymers: Children combine various concentrations of Polyvinyl Alcohol or Elmers 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
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 students own environment
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.
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.
Continued Mt Holyoke Kits 6. Chromatography: Experiments using paper chromatography to extract and separate dyes from black in pens, M&Ms and Skittles were developed. Students learn about solvents, solutes, concentrations, dyes verses lakes, and color separation.
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.
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.
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.
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