Presentation on theme: "CHEMISTRY Unit 02, Lesson 01 Matter’s Changes and Properties."— Presentation transcript:
CHEMISTRY Unit 02, Lesson 01 Matter’s Changes and Properties
2008 CBS News Report John McCain’s office was mailed the following letter with an unidentified white powder inside: “Senator McCain, If you are reading this then you are already DEAD! Unless of course you can't or don't breathe.” The white powder was then tested and determined to not have been toxic.
Construct a Two-Tab Physical vs. Chemical Organizer Instructions: Fold the paper cross-wise along the center dashed-line Cut along the solid line from edge to center fold Color the ‘Physical Properties & Changes’ flap Color the ‘Chemical Properties & Changes’ flap a second color
Phase Change in a Balloon What happened to the volume of the balloon as the liquid ↔ gas? How would you explain this using the terms ‘particles’ and ‘kinetic energy’?
Elasticity: Decision Balls Polynorbornene used mainly in the rubber industry for anti-vibration (rail, building, industry), anti-impact (personal protective equipment, shoe parts, bumpers), and grip improvement (toy tires, racing tires, transmission systems, transports systems for copiers, feeders, etc.) Polyneoprene used in a wide variety of applications, such as laptop sleeves, orthopedic braces (wrist, knee, etc.), electrical insulation, and car fan belts foamed neoprene containing gas cells is used as an insulation material, most notably in wetsuits
Density Application: Aerogels A flower is sitting on a piece of aerogel, the least-dense material created, suspended over a Bunsen burner. Due to its low density, Aerogel has excellent insulating properties, and the flower is protected from the flame. Image source: stardust.jpl.nasa.gov/ photo/aerogel.htmlstardust.jpl.nasa.gov/ photo/aerogel.html
Viscosity: The Pitch Drop Experiment The first Professor of Physics at the University of Queensland, Professor Thomas Parnell, began an experiment in 1927. The experiment demonstrates the fluidity and high viscosity of pitch, a derivative of tar once used for waterproofing boats. In 1927 Professor Parnell heated a sample of pitch and poured it into a glass funnel with a sealed stem. Three years were allowed for the pitch to settle, and in 1930 the sealed stem was cut. From that date on the pitch has slowly dripped out of the funnel - so slowly that now, 77 years later, the ninth drop is only just about to fall. It turns out to be about 100 billion times more viscous than water! Image source: http://www.physics.uq.edu.au/pitchdrop/pitch drop.shtml http://www.physics.uq.edu.au/pitchdrop/pitch drop.shtml
Compressibility: Pneumatics vs. Hydraulics Pneumatics powered by compressed air Hydraulics use pressurized oils or water
Density Compared density of solids > density of liquids > density of gases SolidLiquidGas Most denseLess denseLeast dense
Energy Compared energy of solids < energy of liquids < energy of gases SolidLiquidGas Most denseLess denseLeast dense
Solids’ particles Liquids’ particles Gases’ particles are held tightly and packed fairly close together–they are strongly attracted to each other are in fixed positions but they do vibrate are fairly close together with some attraction between them are able to move around in all directions, but movement is limited by attractions between particles have little attraction between them are free to move in all directions and collide with each other and with the walls of a container and are widely spaced out
Physical vs. Chemical Changes: Hot Pack/Cold Pack When the calcium chloride was dissolved in water, was the process endothermic or exothermic? Was it a physical or a chemical change? What evidence? When the calcium chloride solution was combined with the sodium bicarbonate, was the process endothermic or exothermic? Was is a physical or a chemical change? What evidence?
Phase Change: Heating Curve for Water Image source:
Procedure for powder properties. 1.View the substance using a hand lens and write a brief description including color, particle size, and any other observations. Record the results on your data chart. 2.Add several drops of water to the sample in the 1st column of the Reaction (rxn) Mat and stir with a clean toothpick. Did the powder dissolve? Is there evidence of a chemical rxn? Record results. 3.Dip a small piece of pH paper into the sample water mixture in the first column. Is the mixture acidic, neutral, or basic? Record the results. 4.Add four drops of vinegar to the sample in the second column. Record the results. 5.Add one drop of iodine to the sample in the third column. Record the results. 6.Heat the sample in the foil spoon over a candle flame. Any odors, changes in color, etc. should be recorded. 7.Repeat until all five powders have been tested.
Laboratory Report Guidelines Each student is responsible for submitting a laboratory report that at a minimum: a)discusses the methods used for the identification of the unknown substance b)the data supporting the unknown substance’s identification c)the identification of the unknown substance d)uses the following terms: physical property, chemical property, intensive property, extensive property, physical change, and chemical change