1. Physical & chemical changes
Objective
To know the difference between a chemical and physical change.
What names are given to the 4 changes of state?
Solid to liquid
Liquid to solid
Liquid to gas
Gas to liquid
Melting
Freezing
Evaporating
Condensing

2. Changes of State - Physical changes
Each change of state is given a different name.
Gas
Boiling
Condensing
Melting
Solid
Liquid
Freezing

3. Reversible or irreversible?
Can you get back what you started with? (Reversible) Or is it changed forever? (Irreversible)
Paired talking
I think...because...
I agree because...
I disagree because...
Also...
EXTENSION-
How do you know if a chemical reaction has happened?

4. Signs of a chemical change
…or colder
Bubbles or fizzing
gets warmer…
flames or sparks
Smells (nice or nasty!)
Noises (from loud bangs to quiet fizzing)

5. Chemical changes
Chemical changes (reactions) are usually irreversible.
What do you think this means?
Example: Frying an egg

7. Observing – chemical and physical changes
Write down observations and whether you think these are physical/chemical changes and reversible or not:
Half a test tube Hydrochloric acid + magnesium strip
1cm Sodium hydroxide + 1cm copper sulfate
1cm Hydrochloric acid + 1 cm sodium hydroxide + Universal indicator
Salt + water
Melting ice cube

8. Experiment
Reversible or irreversible?
Physical or chemical change?
Ice cube melting
Kettle boiling
Bunsen burner on
Burning toast
Dissolving salt in water
Boiled egg
Magnesium dropped in acid
Burning splint
Dissolving tablets in water
Baked Cake

9. Physical or chemical change?
Use mini whiteboards