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?