Chapter 9.1 - Temperature
Apr 01, 2015
Chapter 9.1 - Temperature
OutlineI. 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
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 Objects expand or contract depending
on their temperature.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 1526.
Three main temperature scales are being used currently today.
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°
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
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.
Temperature Zero
0 K0 K == -273-273°° C C == -459-459°° F F
00°° F F = = -18-18°° C C == 255 K 255 K
00°° C C == 3232°° F F == 273 K 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 cm1 kg = 2.2 lbs.
Conversions to celsius
From Fahrenheit
t = 5/9 (TF – 32.0)
From Kelvin
t = T - 273
Conversions to Fahrenheit
From Celsius
TF = 9/5 t + 32.0
From KelvinConvert into Celsius then Fahrenheit
Conversions to Kelvin
From Celsius
T = t + 273
From FahrenheitConvert into Celsius then Kelvin
So, what’s next?
Discussion of temperature leads to talk about “heat”
Turn up the Heat!
HotWarm
ColdThese 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.
BurnsYou 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?