Phase Changes

Objectives: SWBAT describe phase changes of water

Catalyst: Describe the law of conservation of matter

in your own words. Kevin thinks that drinking orange juice will

allow him to stay up longer. Identify the independent variable, dependent variable, and control group.

Agenda

Catalyst Phase Changes Phase Change LAB! Exit Question

Law of Conservation of Matter Lab Make sure I check off your procedure

before you start.

You have 30 minutes!

Remember the Kinetic Molecular Theory!

In the 3 different states, temperature is directly related to particle movement T

emp

erat

ure

3 common states of matter

Solid- molecules are tightly arranged

Liquid- molecules flow over each other

Gas- molecules are further apart and move fast

Phase Changes

Key Point #1: When you change the amount of heat energy in a substance it will change from one state to another.

Ok, so how does it work?

So say I have my beaker of ice and I add some heat?

What is going to happen to the temperature?

Of course, the temperature goes up…

Temperature vs Heat Graph(During Phase Change)

Tem

pera

ture

(˚C

)

Heating Time (min)

Solid

If you ADD Heat

DUH MR. J WHY ARE WE DOING THIS? So it will just keep going up right?

NO! It is about to change phase and something very interesting happens…

Temperature vs Heat Graph(During Phase Change)

Tem

pera

ture

(˚C

)

Heating Time (min)

Solid

If you ADD Heat

You are still adding the same heat, but the temperature doesn’t increase when…

IT IS CHANGING PHASE!

What is happening on a particle level during a phase change?

Key Point #2: The energy added to a substance is NOT

used to raise the temperature but instead to pull the particles apart from

each other

It is a transition time!

What will happen if we keep adding heat?

Temperature vs Heat Graph(During Phase Change)

Tem

pera

ture

(˚C

)

Heating Time (min)

Solid

Liquid

If you ADD Heat

Phase Change!!

What will happen if we keep adding heat?

Temperature vs Heat Graph(During Phase Change)

Tem

pera

ture

(˚C

)

Heating Time (min)

Solid

Liquid

If you ADD Heat

Phase Change!!

Phase Change!!

What will happen if we keep adding heat?

Temperature vs Heat Graph(During Phase Change)

Tem

pera

ture

(˚C

)

Heating Time (min)

Solid

Liquid

GasIf you ADD Heat

Phase Change!!

Phase Change!!

WHO’S PAYING ATTENTION?

What happens as you heat up a solid?

What happens during a phase change?

We have a name for the two phase change points

What do you think it is called when a solid moves to a liquid? MELTING POINT!!

What do you think it is called when a liquid turns into a gas? BOILING POINT!! (OR VAPORIZATION POINT!!)

Temperature vs Heat Graph(During Phase Change)

Tem

pera

ture

(˚C

)

Heating Time (min)

Solid

Liquid

GasIf you ADD Heat

Phase Change!!

Phase Change!!

Melting Point!

Boiling Point!

What if you take away heat?

SAME THING JUST GOING DOWN!

YOU WANT A GRAPH?!?!

YOU GOT IT!

Temperature vs Heat Graph(During Phase Change)

Tem

pera

ture

(˚C

)

Heating Time (min)

Solid

Liquid

GasIf you ADD Heat

If you REMOVE Heat

We have a name for the two more phase change points

What do you think it is called when a gas cools to a liquid? CONDENSATION POINT!!

What do you think it is called when a liquid turns into a solid? FREEZING POINT!!

Some vocabulary

Key Point #3: You must know the four points to look out for on a phase change graph.

Heating Up: Solid Liquid = Melting Point Liquid Gas = Boiling Point

Cooling Down: Gas Liquid = Condensation Point Liquid Solid = Freezing Point

Temperature vs Heat Graph(During Phase Change)

Tem

pera

ture

(˚C

)

Heating Time (J)

Solid

Liquid

Gas

Freezes

Condenses

Melts

Boils

Melting Point

Boiling PointIf you ADD Heat

If you REMOVE Heat

Condensation Point

Freezing Point

Time to do it yourself!!

Phase change lab time.

Exit Question

Draw the temperature vs. time graph for water that is being heated.

Explain why it makes this shape.