Chapter 9.1 - Temperature

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Chapter 9.1 - Temperature
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Outline

• I. Particle Motion
• A. Review
• II. Temperature
• A. Definition
• III. Thermometers
• A. Definition
• B. Functioning
• C. Examples

• IV. Temperature Scales
• A. Fahrenheit
• B. Celsius
• C. Kelvin
• V. Conversions
• A. to Celsius
• B. to Fahrenheit
• C. to Kelvin

VI. Heat A. Subjectivity B. Definition C. Burns
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Review ? Particle Motion

• Remember the three statements Dalton made about
  particles!
• Big particles move slower than small ones.
• Particles are always in motion.
• The higher the temperature the faster the
  particles move.

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Temperature

• What is it?
• What does it have to do with particle motion?

• DEFINITION
• The average kinetic energy of all the particles
  in an object
• This average is different than the total KE
• How?

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Thermometers

• DEFINITION
• A device that measures temperature
• Essentially, they are just a type of radar gun!
• Thats because they are simply measuring how fast
  particles are moving.

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How Thermometers Work

• Early thermometers worked because of one main
  principle.
• Objects expand or contract depending on their
  temperature.
• Hotter objects EXPAND
• Why?
• Cooler objects CONTRACT
• Why?

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More Functioning

• Most thermometers rely on the expansion of a
  fluid
• Such as mercury or alcohol
• Some thermometers rely on the expansion
  difference between two different metals
• Such as a refrigerator or thermostat
• New, modern thermometers rely on electronics or
  infrared.

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Modern Thermometers
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Temperature Scales

• A thermometer is worthless unless it is
  calibrated.
• Many people came up with scales to use.
• The first thermometer is credited to Galileo in
  1526.
• Three main temperature scales are being used
  currently today.

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FAHRENHEIT SCALE

• Created by Gabriel Fahrenheit
• (1686-1736) GERMAN
• Scale is based on body temperature and a salt
  water mixture
• Everyday use only in the U.S. and Jamaica.
• Had to be corrected over the years to the
  familiar 32 freezing and 212 boiling for water.
• And a body temperature of 98.6

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CELSIUS SCALE

• Created by Anders Celsius
• (1701-1744) SWEDISH
• Scale was based on the freezing and boiling of
  water.
• This is the metric unit for temperature.
• Gives us the O freezing and 100 boiling points

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KELVIN SCALE

• Named for Lord Kelvin
• (1824-1907) BRITISH
• Named in 1954
• Kelvin is the SI unit for temperature.
• Uses the Celsius scale with one major difference.
• 0 Kelvin is based on absolute zero.
• Absolute zero is a theoretical point where all
  particle movement stops.

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Temperature Zero
0 K -273 C -459 F
0 F -18 C 255 K
0 C 32 F 273 K
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CONVERSIONS

• Just like every other type of measurement there
  needs to be a conversion from one unit to another
• Examples
• 1 hp 746 w
• 1 inch 2.54 cm
• 1 kg 2.2 lbs.

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Conversions to celsius

• From Fahrenheit
• t 5/9 (TF 32.0)
• From Kelvin
• t T - 273

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Conversions to Fahrenheit

• From Celsius
• TF 9/5 t 32.0
• From Kelvin
• Convert into Celsius then Fahrenheit

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Conversions to Kelvin

• From Celsius
• T t 273
• From Fahrenheit
• Convert into Celsius then Kelvin

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So, whats next?

• Discussion of temperature leads to talk about
  heat

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Turn up the Heat!

• Hot
• Warm
• Cold
• These are subjective terms.

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• Heat
• Definition
• The energy transfer from one object to another
• because of a temperature difference.
• Heat is NOT contained in an object.
• I do not have heat in me.

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Burns

• You can be burned by
• really hot objects
• stove, curling iron, fire, etc.
• And!
• really cold objects
• ice, dry ice, liquid nitrogen, etc.
• How can this be possible?