1. S1 Chemistry Introduction to Chemistry
Changing state
S1 Chemistry
Introduction to Chemistry

2. Does water change weight when it melts?
Ice takes up less space when it melts so it gets lighter.
Ice floats on water, so it must get heavier when it melts.
Ice will stay the same weight when it melts.
Does water change weight when it melts?

3. Maybe the ice has melted on the outside of the glass.
I think some of the water must have leaked out of the glass.
I think that water has come from the air.
Why are there drops of water on the outside of a glass of iced lemonade?

4. Learning outcomes Success criteria
Understand how matter can change from one state to another.
You can name the term used to describe changes of state from:
solid → liquid
liquid → gas
gas → liquid
liquid → solid
You can explain what “evaporating” is.
You can state whether each of these state changes requires heat energy or removes heat energy.
You can explain what is meant by the “melting point” and “boiling point” of a substance.

6. Melting and Freezing
Melting Point (m.p.): the temperature a substance turns into a liquid at.
Freezing Point (f.p.): the temperature a substance turns into a solid at.
For any substance, the melting and freezing points are EXACTLY THE SAME.

7. 0 ºC

8. 36 ºC

9. 1500 ºC

10. -17 ºC

11. -210 ºC

12. Deliberate mistakes: melting and freezing
Melting and freezing are opposites of each other. To freeze a substance you heat it up and the liquid turns into a solid. This means that the particles become more spread out.
Water freezes at 0ºC and all substances freeze at this temperature. Because of this, whenever a substance freezes it will feel cold.

13. Deliberate mistakes: melting and freezing
Melting and freezing are opposites of each other. To freeze a substance you heat it up and the liquid turns into a solid. This means that the particles become more spread out.
Water freezes at 0ºC and all substances freeze at this temperature. Because of this, whenever a substance freezes it will feel cold.

14. Learning outcomes Success criteria
Understand how matter can change from one state to another.
You can name the term used to describe changes of state from:
solid → liquid
liquid → gas
gas → liquid
liquid → solid
You can explain what “evaporating” is.
You can state whether each of these state changes requires heat energy or removes heat energy.
You can explain what is meant by the “melting point” and “boiling point” of a substance.