Changing state

Changing stateS1 Chemistry

Introduction to Chemistry

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.

Why are there drops of water on the outside of a glass of

iced lemonade?

I think some of the water must have leaked out

of the glass.I think that water has come from

the air.

Maybe the ice has

melted on the outside of the glass.

Learning outcomes Success criteriaUnderstand 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.

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.

0 ºC

36 ºC

1500 ºC

-17 ºC

-210 ºC

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.

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.

Learning outcomes Success criteriaUnderstand 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.