today’s special turn in practice test & lab on front table test 9 thermal energy turn in test...
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Today’s special
• Turn in Practice test & Lab on front table
• Test 9 Thermal energy
• Turn in test and work on Vocab sheet quietly, without talking
• Vocab 10 due next
• Notes!
Heat transfer and phase change
PAc.1: Distinguish chemical properties of matter (including reactivity) from physical properties of matter (including boiling point, freezing/melting point, density
[with density calculations], solubility, viscosity, and conductivity).
PAc.6: Compare the properties of the four states of matter—solid, liquid, gas, and plasma—in terms of the arrangement and movement of particles.
PAc.7: Explain the processes of phase change in terms of temperature, heat transfer, and particle arrangement.
PAa.2: Use appropriate laboratory apparatuses, technology, and techniques safely and accurately when conducting a scientific investigation.
PAa.9: Use appropriate safety procedures when conducting investigations.
Write it on your heart that every day is the best day
of the year.
Ralph Waldo Emerson
Fact: Every year, the moon moves ½ inch further from the earth.
Today’s special
• Homework check (Vocab 10)
• Test results
• Notes
• HW I due next
• Activity (Practice book)
Question
• Why does water in a car radiator sometimes boil explosively when the radiator cap is removed?
Conduction
• Transfer of heat by means of particles, mainly electrons
• Metals have freely moving electrons, and are generally good conductors
Insulators
• Substances with electrons that do not move freely
• Wood, air, rubber
Home insulation
• Has “R” rating according to climate
Today’s special
• Safety moment
• Notes
• Class work time
The best insulator
• Dead air space, i.e.:
• Double pane windows
• Polystyrene
Convection
• Heat transfer by motion of currents in fluids, liquid or gas
What is forced convection?
• The currents are helped along by adding a fan
Radiation
• (radiant energy, NOT radioactivity!)
• Transfer of heat energy by electromagnetic waves
radiant energy
• All substances above absolute zero absorb, emit, and reflect radiant energy
Phase change
• A change of state from solid, liquid, or gas
Today’s special
• HW check
• A few more notes
• Lab
Today’s special
• HW I check
• Upcoming schedule
• Chapter project & HW II
• Safety project & Take-home test
• Lab
• A few more notes
Evaporation
• Molecules absorb energy until they can break free of the liquid
condensation
• Molecules give up their energy to a liquid
Boiling and pressure
• Boiling points can be changed by increasing or decreasing pressure
• Increased pressure prevents molecules from leaving (pushing down on the “pile”)
• Decreased pressure helps molecules to leave (helping the football players up)
Pressure cooker
Melting and freezing
• Add energy, molecules move more and substance melts
• Take out energy, molecules slow down and arrange themselves into a solid
• Adding a “foreign” substance interferes with the crystal formation process
Melting ice
Question
• Why does water in a car radiator sometimes boil explosively when the radiator cap is removed?
Homework
• Chapter HW: pp. 166-168
• I. Review questions2-20 even (due date: ____________)
• II. Exercises 2-20 even; Problems 1-7 (due date: __________)
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