CHEMISTRY
Unit 02, Lesson 01Matter’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.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/pitchdrop.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
Solid Liquid Gas
Most dense Less dense Least dense
Energy Compared
energy of solids < energy of liquids < energy of gases
Solid Liquid Gas
Most dense Less dense Least 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 PackWhen 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?
Physical vs. Chemical Properties and Changes
Phase Change: Sublimation
Phase Change: Condensation
Phase Change: Heating Curve for Water
Image source:
Procedure forpowder 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 GuidelinesEach 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 substanced) uses the following terms: physical property,
chemical property, intensive property, extensive property, physical change, and chemical change
STAAR Sample Test Question TEKS C.2E & C.4B