CHEMISTRY

CHEMISTRYUnit 02 Lesson 01

Matter’s Changes and Properties

In the News…

A threatening letter containing an unidentified white powder was received at a political candidate’s office. As a precaution, many people were sent to the hospital for examination or were quarantined while authorities tried to determine if the powder was hazardous.

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 Demonstration

• 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 Station: 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 on a piece of aerogel which is suspended over a Bunsen burner. [Due to its low density] Aerogel has excellent insulating properties, and the flower is protected from the flame.” (NASA 2009)

Image source: NASA

Viscosity: The Pitch Drop Experiment

“The first Professor of Physics at the University of Queensland [Australia], 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. At room temperature pitch feels solid - even brittle - and can easily be shattered with a blow from a hammer. It's quite amazing then, to see that pitch at room temperature is actually fluid!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, [many] years later, the ninth drop is only just about to fall.” ("The pitch drop," 2012)

Compressibility: Pneumatics and Hydraulics

Pneumatics Uses compressed air

HydraulicsUses pressurized oils or

water

Shape and Volume Compared

density of solids > density of liquids > density of gases

Solid Liquid Gas

Definite shape and volume

Definite volume; take shape of container

Take shape of and fill volume of container

Density Compared

density of solids > density of liquids > density of gases

Solid Liquid Gas

Most dense Less dense Least dense

Particle Motion Energy Compared

energy of solids < energy of liquids < energy of gases

Solid Liquid Gas

Least motion energy Less motion energy Most motion energy

Particles in Solids

Particles in Liquids

Particles in Gases

Are held tightly and packed fairly close together–strong attractions

Are in fixed positions and can vibrate

Are fairly close together with some attractions among them

Are able to move around each other as determined by attractions

Have little to no attractions among them – are widely spaced out

Are free to move in all directions; collide with each other and with the walls of a container

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?

Intensive vs. ExtensiveProperties

Physical vs. Chemical Properties

and Changes

Phase Change: Sublimation

Phase Change: Condensation

Phase Change: Heating Curve for Water

(Cawang, 2011)

Testing Procedures 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 first 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.

ReferencesNASA. (Photographer). (2009). Aerogelflower filtered. [Print Photo].

Retrieved from http://commons.wikimedia.org/wiki/File:Aerogelflower.jpg.

The pitch drop experiment. (2012). Retrieved from http://smp.uq.edu.au/content/pitch-drop-experiment.

Bartelt, T. (n.d.). Comparing hydraulics and pneumatics. Retrieved from http://www.wisc-online.com/objects/ViewObject.aspx?ID=HYP4307

Cawang. (Artist). (2011). Water phase change diagram. [Web Drawing]. Retrieved from http://commons.wikimedia.org/wiki/File:Water_Phase_Change_Diagram.png