Chapter 4Chapter 4Changes of State Changes of State

Warm-Up Warm-Up 10/14/1010/14/10

Two pots of boiling water each cook an egg. One pot is at a high elevation. The other pot is at sea level. It takes one minute longer to hard-boil the egg at high elevation. Why?

(Think pressure and temperature)

Energy and Changes of Energy and Changes of State State

A A change of statechange of state is the change of a is the change of a substance from one substance from one physicalphysical form to form to another. another.

To change from one state to another you To change from one state to another you must add of remove must add of remove energy (heat).energy (heat).

Melting / Freezing Melting / Freezing

Freezing pointFreezing point – – liquid changes into liquid changes into solid. solid.

Melting PointMelting Point - solid - solid changes into liquid.changes into liquid. Same Temperature Same Temperature

Water : 0º CWater : 0º C

Evaporation/ Boiling Evaporation/ Boiling

Evaporation:Evaporation: liquid liquid at the surface at the surface changes into gaschanges into gas Can happen below boiling pointCan happen below boiling point

Boiling:Boiling: liquid liquid throughoutthroughout changes into changes into gas. gas.

Pressure Pressure

Pressure effects states of matter too: Pressure effects states of matter too: Less pressure = lower boiling pointLess pressure = lower boiling point More pressure = higher boiling point More pressure = higher boiling point

Boiling / Condensation Boiling / Condensation

BoilingBoiling: liquid to gas: liquid to gas CondensationCondensation: gas to liquid : gas to liquid Same temperature : Water 100º CSame temperature : Water 100º C

Sublimation Sublimation

When a substance goes directly from a When a substance goes directly from a solid to a gas. solid to a gas.

(Dry Ice) (Dry Ice)

Homework Homework

Section Review: Section Review: Copy down the questionsCopy down the questions Page 119, # 1-7Page 119, # 1-7