Heating Cooling Curves Do Now Name the phase

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Heating & Cooling Curves Do Now: Name the phase change S L Melting (fusion)

Heating & Cooling Curves Do Now: Name the phase change S L Melting (fusion) L G Boiling (vaporization) G L condensation L S Freezing (solidification) S G sublimation G S deposition

All Phase changes accompanied by energy changes • Phase changes are physical changes: –

All Phase changes accompanied by energy changes • Phase changes are physical changes: – sometimes energy is absorbed (endothermic) – sometimes energy is released (exothermic) • Energy change for given phase change can be measured/calculated (we’re going to learn how to do this tomorrow)

 • As you go from S L G, you are increasing the distance

• As you go from S L G, you are increasing the distance between molecules, so you are increasing their PE ! Endothermic Gas PE Sublimation Deposition Vaporization Condensation Melting (fusion) Freezing (solidification) Liquid Solid Exothermic We can see these energy changes by looking at a heat/cooling curve – next slide

TURN TO PACKET page 11, take notes here:

TURN TO PACKET page 11, take notes here:

II Temperature I Solid & Liquid Soli d III IV Liquid & Gas Liquid

II Temperature I Solid & Liquid Soli d III IV Liquid & Gas Liquid V Gas ● Boil pt. Melt pt. K. E. P. E. ↔ ● K. E. ↔ P. E. K. E. P. E. ↔ Time K. E. ↔ P. E. K. E. P. E. ↔

During Phase changes • More than one phase is present – Melting : solid

During Phase changes • More than one phase is present – Melting : solid and liquid – Boiling: liquid and gas (lets check out a tiger animation) • temperature is constant: T=0 – There is no change in temp!!!!! ***NOTE: if 2 phases are present, temp is constant

Melting & Boiling Points • Plateaus = Phase changes = PE changes – always

Melting & Boiling Points • Plateaus = Phase changes = PE changes – always given as temp (˚C, K) • WHY IS IT CALLED A POINT?

QUICK QUESTION: What happens to temperature as heat is added at boiling point? •

QUICK QUESTION: What happens to temperature as heat is added at boiling point? • Nothing, temp doesn't’t change until only 1 phase is present!

What do you think a cooling curve would look like?

What do you think a cooling curve would look like?