11 melting & boiling

8/7/2019 11 Melting & Boiling

1/43

MELTING

&BOILING

TOPIC 11: THERMAL PROPERTIES OF MATTER

PreparedbyCg

EdnaMariaHjOsman.E-ma

il:[email protected]
mailto:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]


2/43

WHAT HAPPENS TO MATTER

WHEN THERMAL ENERGY IS

APPLIED TO IT?

PreparedbyCg

EdnaMariaHjOsman.E-ma

il:[email protected]


3/43

OF THE MATTER

THERMAL ENERGY

CAN

Changethe temperature

Changethe state

PreparedbyCg

EdnaMariaHjOsman.E-mail:[email protected]


4/43

WHAT DO WE KNOW?

When heat is applied to a substance.The substance may undergo changes of state.

Heat Energy Applied

Change in Stateof substance

PreparedbyCg



5/43

WHAT DO WE KNOW?

When heat is removed from a substance.The substance may undergo changes of state.

Heat Energy Removed

Change in Stateof substance

PreparedbyCg



6/43

FOCUSON

THESUBSTANCEmELTING&BOILING

PreparedbyCg



7/43

MELTING

A change of state from solid to liquid without a

change in temperature.

PreparedbyCg


SOLID LIQUID

MELTING


8/43

m.p = -117 C

Et

hly

Alc

oho

l

m.p = 0 C

Ice

m.p = 57 C

W

ax

For a puresubstance, melting

occurs at afixedtemperature.

This temperatureis known as

the melting point.

PreparedbyCg



9/43

m.p = 232 C

Tin

m.p = 1060 C

Gold

For a puresubstance, meltingoccurs at a

fixedtemperature.


the melting point.

PreparedbyCg



10/43

DETERMINATION OF MELTING POINT

The solid is slowly heated until all the solid melts.

PreparedbyCg

EdnaMariaHjOsman.E-mail:edna.maria.osman@gmai

l.com

Procedures

Record the initial temperatureof the solid.1

Start heating with a slow

flame from a Bunsen burner.2


11/43



PreparedbyCg


l.com

Procedures

Take readings of

temperature every minute

until all the solid has melted

and the temperature of the

liquid reaches a certaintemperature.

3


12/43



PreparedbyCg


l.com

Procedures

Plot a graph of temperature

against time.4


13/43

-10

0

10

20HEATING CURVE OF ICE

Tem

perature/

C

Time / min


The graph is a smooth curvewith a horizontal section.

Heating curves are used to

determine melting points.

PreparedbyCg



14/43

-10

0

10

20HEATING CURVE OF ICE

Tem

perature/

C

Time / min


The horizontal lineindicatesa change of state.

Refer to the temperature

axis for the melting point!

PreparedbyCg



15/43


16/43

SOLIDIFICATION

A change of state from liquid to solid without a


PreparedbyCg


SOLID LIQUID

FREEZING


17/43

Napthalene

freezing pt = 79 C

Forapure substance,freezing occursat a

fixedtemperature.


the freezing point.

PreparedbyCg



18/43

DETERMINATION OF FREEZING POINT

The liquid is slowly cooled until all the liquid freezes.

Procedures

Record the initial temperature

of the liquid.1

Take readings of temperature

every minute until all the liquid

freezes and the temperature ofthe solid reaches a certain

temperature.

2

PreparedbyCg



19/43


The liquid is slowly cooled until all the liquid freezes.

Procedures

Plot a graph of temperatureagainst time.

3

PreparedbyCg



20/43

65

70

75

80

85

90

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

COOLING CURVE OF NAPTHALENE

Temperature/

C

Time / min


Cooling curves are used to

determine freezing points.

PreparedbyCg

EdnaMariaHjOsman.E-m

ail:[email protected]


21/43

65

70

75

80

85

90

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18


Temperature/

C

Time / min


The horizontal lineindicatesa change of state.


axis for the freezing point!PreparedbyCg




22/43

65

70

75

80

85

90

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18


Temperature/

C

Time / min



axis for the freezing point!

Freezing point isthe temperature atwhich a liquid changes to a solid.

PreparedbyCg




23/43

MELTING POINT & FREEZING POINT

A pure substance will solidify/ freeze at atemperature equal to its melting point.

PreparedbyCg



SOLID LIQUID

MELTING

FREEZING

Melting Point

of Substance

Freezing Point

of Substance=


24/43

BOILING

A change of state from liquid to gas without a


PreparedbyCg



LIQUID GAS

BOILING


25/43


26/43

For a pure substance, boiling occurs ata

fixedtemperature.


the boiling point.

b.p = 35 C

Ether

b.p = 79 C

Alcohol

PreparedbyCg




27/43

For a pure substance, boiling occurs ata

fixedtemperature.


the boiling point.

b.p = 357 C

Mercury

b.p = 100 C

Water

PreparedbyCg




28/43

DETERMINATION OF BOILING POINT

-10

1030

50

70

90

110HEATING CURVE OF WATER

Temperature/

C

Time / min

Heating curves arealso used to determine

boiling points.

PreparedbyCg




29/43


-10

1030

50

70

90


Temperature/

C

Time / min

These horizontal linesindicate

changes of state.

PreparedbyCg




30/43


-10

1030

50

70

90


Temperature/

C

Time / min

Theupper horizontallinesindicateliquid to

gasconversion

Refer to thetemperature axisfor the boiling

point!

PreparedbyCg


ail:edna.maria.osman@gma

il.com


31/43


-10

1030

50

70

90


Temperature/

C

Time / min

Thelower horizontallinesindicatesolid to

liquidconversion

Refer to thetemperature axisfor the melting

point!

PreparedbyCgEdnaMariaHjOsman.E-m


il.com


32/43

CONDENSATION

A change of state from gas to liquid without a




il.com

LIQUID GAS

CONDENSATION


33/43



il.com

LIQUID GAS

CONDENSATION

BOILING

BOILING POINT & CONDENSATION POINT

A pure substance will condense at a temperatureequal to its boiling point.

Condensation Point

of Substance

Boiling Point of

Substance=


34/43

WHY IS

THE TEMPERATURECONSTANT DURING

CHANGES OF STATE?PreparedbyCgEdnaMariaHjOsman.E-m


il.com


35/43


36/43


37/43

LATENT HEATAll the thermal energy is used to break/create the

substances intermolecular bonds during changes of state.



il.com

SOLIDLIQUIDGAS

CreatingBonds

CreatingBonds

Breaking

Bonds

Breaking

Bonds

None of the thermal energy is used to change the kinetic

energy of the particles during changes of state.

There will be no change in the temperature of the substance.

SUMMARIZATION


38/43

SUMMARIZATION

-10

10

30

50

70

90

110

A HEATING CURVE

Te

mperature/

C

Time / min

Boiling

Melting

Solid &

LiquidPresent

Liquid &Gas

Present

LiquidPresent

SolidPresent



il.com


39/43


40/43


41/43

SUMMARIZATION


42/43

MELTING POINT & FREEZING POINTA pure substance will solidify/ freeze at a

temperature equal to its melting point.



il.com

SOLID LIQUID

MELTING

FREEZING

Melting Point

of Substance

Freezing Point

of Substance=

SUMMARIZATION


43/43

11 melting & boiling

Documents