Defining Phases of

Matter

Solids GasesLiquidsM

icro

Macr

o

Solids GasesLiquids

-has its own shape

-don’t really flow

-particles barely moving, low energy

-takes the shape of its container

-flow

-particles moving, medium energy

-takes the shape of its container

-flow

-particles moving fast, high energy

What is heat?

How much motion do the molecules have?

Let’s Talk about Gases

Gases have a tremendous capacity to expand or contract with change in temperature

What happened to the size of our balloons as the temperature got colder?

1. Why? (Write this down)

2. Liquid nitrogen is – 196 degrees C

3. The balloons shrank a lot!

4. Is there a temperature that the balloons would have shrunk to nothing? Write down what you think.

THE KELVIN SCALE OF TEMPERATURE

•in the nineteenth century, Lord Kelvin, an Englishman, invented an new temperature scale suitable for measuring low temperatures

•When a material is cooled, it looses heat, and its temperature decreases, until a point is reached where it has no more heat left to loose

•At this point it is not possible to lower the temperature any further

•This low temperature is called absolute zero

How Cold Can Things Get?Absolute Zero

•0 degrees K (Kelvin)

•-273.15 degrees (Celsius)

•At temperatures near 0 K, nearly all molecular motion ceases

•If there is no motion, then there is essentially no volume

•Lowest Natural Temperature Ever Recorded on Earth, −89.2 °C

•Lowest Man-Caused Temperature - MIT scientists have cooled a sodium gas to the lowest temperature ever recorded -- only half-a-billionth of a degree above absolute zero

•The laws of thermodynamics state that absolute zero cannot be reached

•

The Kelvin Scale is useful for solving gas

law problems

Temperature Degree

s Celsius

Degrees Kelvin

DegreesFahrenhei

t

°C °K °F

Boiling point of water 100 373 212

Average human body temperature 37 310.1 98.6

Melting point of ice 0 273 32

Liquid nitrogen -196 77 -325

Absolute 0 -273 0 70

Common temperature comparisons:

Hot air balloons were extremely popular in France in the 1800s

French scientist Jacques Charles made measurements on how the volume of a gas was affected by the temperature of the gas.

Why Do Hot Air Balloons Fly?

Charles’s LawThe volume of a gas varies directly with

the temperature in degrees Kelvin

Volume = Constant x Temperature

Example 1. Volume = 1 cm3 at 1 degree Kelvin

•What is the volume if we raise the temperature to 2 degrees K?

Starting Temperature Ending TemperatureStarting Volume °K °K Ending Volume (%)

1 1 2 200%1 2 4 200%1 10 20 200%1 100 200 200%

Balloons 300 100 ?

The Change in Volume is Proportional to:

Ending temperature (°K) divided by starting temperature (°K)