Changes in States of MatterChanges in States of Matter

Changes in States of MatterChanges in States of Matter

Change in StateChange in State MeltingMelting FreezingFreezing Boiling (Vaporization)Boiling (Vaporization) CondensationCondensation SublimationSublimation DepositionDeposition

Process of ChangeProcess of Change

solid to liquidsolid to liquid liquid to solidliquid to solid liquid to gasliquid to gas gas to liquidgas to liquid Solid to gasSolid to gas Gas to solidGas to solid

Vaporization - the change from a liquid to Vaporization - the change from a liquid to a gas below its boiling point.a gas below its boiling point.

Evaporation - vaporization of an Evaporation - vaporization of an uncontained liquid ( no lid on the bottle ).uncontained liquid ( no lid on the bottle ).

Liquid to Gas Phase ChangeLiquid to Gas Phase Change

EvaporationEvaporation

Molecules at the surface break away Molecules at the surface break away and become gas.and become gas.

Only those with enough KE escapeOnly those with enough KE escape Evaporation is a cooling Evaporation is a cooling process.process. It requires energy.It requires energy.

BoilingBoiling

vapor pressure = the external pressurevapor pressure = the external pressure Temperature is called the boiling pointTemperature is called the boiling point Normal Boiling pointNormal Boiling point is the temperature a is the temperature a

substance boils at 1 atm pressure.substance boils at 1 atm pressure. The temperature of a liquid can never rise The temperature of a liquid can never rise

above it’s boiling pointabove it’s boiling point Energy goes into breaking forces, not Energy goes into breaking forces, not

moving faster.moving faster.

Changing the Boiling PointChanging the Boiling Point

Lower the pressure (going up into the Lower the pressure (going up into the mountains).mountains).

Lower external pressure requires lower Lower external pressure requires lower vapor pressure.vapor pressure.

Easier to make bubblesEasier to make bubbles

Raise the external pressure (Use a Raise the external pressure (Use a pressure cooker)pressure cooker)

Raises the vapor pressure needed.Raises the vapor pressure needed. Harder to make bubblesHarder to make bubbles Raises the boiling point.Raises the boiling point.

Changing the Boiling PointChanging the Boiling Point

Different Boiling pointsDifferent Boiling points

Different substances boil at different Different substances boil at different temperatures because they have different temperatures because they have different intermolecular forcesintermolecular forces Weak forces- lower boiling pointWeak forces- lower boiling point

Gas to Liquid Phase ChangeGas to Liquid Phase Change CondensationCondensation

Molecules stick togetherMolecules stick together Releases energy.Releases energy.

Can occurs between Can occurs between condensation and condensation and evaporationevaporation

1. When first sealed 1. When first sealed the molecules the molecules gradually escape the gradually escape the surface of the liquidsurface of the liquid

Dynamic equilibriumDynamic equilibrium

2. As the molecules build up 2. As the molecules build up above the liquid some condense above the liquid some condense back to a liquid.back to a liquid.

Dynamic equilibriumDynamic equilibrium

3. As time goes by the rate of vaporization 3. As time goes by the rate of vaporization remains constantremains constant

4. but the rate of condensation increases 4. but the rate of condensation increases because there are more molecules to because there are more molecules to condense.condense.

Dynamic equilibriumDynamic equilibrium

5. Equilibrium is reached when5. Equilibrium is reached when

Rate of VaporizationRate of Vaporization = = Rate of CondensationRate of Condensation

Molecules are constantly changing Molecules are constantly changing phase phase “Dynamic”“Dynamic”

The amount of liquid and vapor remains The amount of liquid and vapor remains constant constant “Equilibrium”“Equilibrium”

Dynamic equilibriumDynamic equilibrium

Vapor PressureVapor Pressure In a closed container the gas In a closed container the gas

molecules will cause pressure.molecules will cause pressure. The pressure at equilibrium is called The pressure at equilibrium is called

vapor pressurevapor pressure Different compounds have different Different compounds have different

vapor pressures because of different vapor pressures because of different intermolecular forcesintermolecular forces

Stronger forces, lower vapor pressureStronger forces, lower vapor pressure

Pre

ssur

e (k

Pa)

Temperature (°C)

Freezing

Deposition

Condensation

Gas

Liquid

Solid

Boiling/Evaporation (Vaporization)

Sublimation

Melting

Triple Point (All 3 states of Matter exist)

Normal Melting Point. (Tm)

Normal Boiling Point. (Tb)

101.3 (kPa)

Critical Point

Triple PointTriple Point ~ point on a phase diagram that ~ point on a phase diagram that represents all three phasesrepresents all three phases

Normal Melting PointNormal Melting Point ~ melting point of a ~ melting point of a solid at a pressure of 101.3 kPa or 1atm solid at a pressure of 101.3 kPa or 1atm

Normal Boling PontNormal Boling Pont ~ boiling point of a liquid ~ boiling point of a liquid at a pressure of 101.3 kPa or 1atm at a pressure of 101.3 kPa or 1atm

Critical PointCritical Point ~ distinction between the liquid ~ distinction between the liquid and gaseous phases is almost non-existent and gaseous phases is almost non-existent

TP of WaterTP of Water

Triple Point CO2Triple Point CO2

TP Iodine TP Iodine

Sublimation Sublimation

Solid

Liquid

Gas

Melting

Boiling

Condenses

Freezing

Energy is put in from solid to gas (warms)

Energy is removed from gas to solid (Cools)

Phase DiagramsPhase Diagrams

Pressure ( atm

)

Temperature (°C)

Solid/liquidLiquid/gas