Chapter Temperature

Outline I. Particle MotionParticle Motion A. Review II. TemperatureTemperature A. Definition III. ThermometersThermometers A. Definition B. Functioning C. Examples IV. Temperature ScalesTemperature Scales A. Fahrenheit B. Celsius C. Kelvin V. ConversionsConversions A. to Celsius B. to Fahrenheit C. to Kelvin VI. HeatHeat A. Subjectivity B. Definition C. Burns

Review  Particle Motion  Remember the three statements Dalton made about particles! 1. Big particles move slower than small ones. 2. Particles are always in motion. 3. The higher the temperature the faster the particles move.

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?

Thermometers  DEFINITION : –A device that measures temperature  Essentially, they are just a type of radar gun!  That’s because they are simply measuring how fast particles are moving.

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?

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.

Modern Thermometers

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  Three main temperature scales are being used currently today.

FAHRENHEIT SCALE  Created by Gabriel Fahrenheit –( ) 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°

CELSIUS SCALE  Created by Anders Celsius –( ) 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

KELVIN SCALE  Named for Lord Kelvin –( ) 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.

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

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.

Conversions to celsius  From Fahrenheit t = 5 / 9 (T F – 32.0)  From Kelvin t = T - 273

Conversions to Fahrenheit  From Celsius T F = 9 / 5 t  From Kelvin Convert into Celsius then Fahrenheit

Conversions to Kelvin  From Celsius T = t  From Fahrenheit Convert into Celsius then Kelvin

So, what’s next? Discussion of temperature leads to talk about “heat”

Turn up the Heat! Hot Warm Cold These are subjective terms.

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.

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?