November 26 November 26 DO NOW: FILL IN THE DO NOW: FILL IN THE BLANKSBLANKS

• Ideal gases particles have no ________ Ideal gases particles have no ________ and they have no ________ to each other.and they have no ________ to each other.

• Best conditions for ideal behavior are Best conditions for ideal behavior are ___________ pressure and ___________ pressure and _________temperature._________temperature.

• At ____ pressure and _____ temperature At ____ pressure and _____ temperature gases deviate more from ideal gases deviate more from ideal behavior.behavior.

What is the difference between What is the difference between evaporation and boiling?evaporation and boiling?

Objectives :* LiquidsObjectives :* Liquids

* Vapor pressure* Vapor pressure

* Identify the factors that affect* Identify the factors that affect

vapor presure vapor presure

* Learn to use table H* Learn to use table H

* Intermolecular attractions* Intermolecular attractions

* Evaporation* Evaporation

* Boiling* Boiling

LIQUIDS

LIQUIDLIQUID

• A form of matter that has definite A form of matter that has definite volume but no definite shape. volume but no definite shape.

• A liquid takes the shape of the A liquid takes the shape of the container is in.container is in.

• Particles are hold together by forces Particles are hold together by forces of attractions that are called of attractions that are called intermolecular forces.intermolecular forces.

VAPORVAPOR

• The gas phase of a substance that is The gas phase of a substance that is ordinarily a solid of liquid at that ordinarily a solid of liquid at that temperature.temperature.

• The vapor above the surface of a The vapor above the surface of a liquid exerts a characteristic liquid exerts a characteristic pressure called vapor pressure.pressure called vapor pressure.

EVAPORATIONEVAPORATION

• It happens at ALL It happens at ALL temperatures and temperatures and only at the only at the surfacesurface of of the liquid.the liquid.

• The molecules at the The molecules at the surface that can surface that can escape the liquid escape the liquid inside a closed inside a closed container produce container produce the vapor pressure.the vapor pressure.

VAPOR PRESSURE VAPOR PRESSURE OF A LIQUIDOF A LIQUID

• Pressure exerted Pressure exerted by the gas above by the gas above the liquid in a the liquid in a closed system.closed system.

• Measured with a Measured with a manometer.manometer.

• It increases with It increases with temperaturetemperature..

TABLE H – TABLE H – vapor pressure of pressure of four liquids four liquids

• *Evaporation is an endothermic *Evaporation is an endothermic process. When a liquid evaporates process. When a liquid evaporates absorbs heat from the surroundings. absorbs heat from the surroundings.

• If the liquid is evaporating over our If the liquid is evaporating over our skin we feel cold.skin we feel cold.

• Transpiration is a cooling process. Transpiration is a cooling process. Explain why. Explain why.

STRONG INTERMOLECULAR STRONG INTERMOLECULAR ATTRACTIONSATTRACTIONS

• If a liquid has STRONG intermolecular If a liquid has STRONG intermolecular attractions the molecules tend to attractions the molecules tend to stay together as liquid.stay together as liquid.

• A lot of energy is needed to separate A lot of energy is needed to separate the molecules. The liquid will have the molecules. The liquid will have

• * LOW VAPOR PRESSURE and* LOW VAPOR PRESSURE and

• * HIGH BOILING POINT * HIGH BOILING POINT

• Liquids with Liquids with weakweak forces of forces of attraction will have attraction will have

• *high vapor pressure and *high vapor pressure and

• *low boiling points.*low boiling points.

BoilingBoiling

• A liquid boils when the vapor A liquid boils when the vapor pressure of the liquid equals the pressure of the liquid equals the external pressure.external pressure.

• The temperature at which the liquid The temperature at which the liquid boils is the boiling point.boils is the boiling point.

NORMAL BOILING POINTNORMAL BOILING POINT

• The temperature at which the vapor The temperature at which the vapor pressure of the liquid is equal to pressure of the liquid is equal to 1atm or 101.3 kPa.1atm or 101.3 kPa.

• For water is 1000C.For water is 1000C.

• Its vapor pressure at that Its vapor pressure at that temperature is 101.3 kPa.temperature is 101.3 kPa.

• (Table H)(Table H)

CONDENSATIONCONDENSATION

• the phase change from liquid to gas. the phase change from liquid to gas. It is an exothermic process. It is an exothermic process.

NOVEMBER 4NOVEMBER 4

• HOW TO SEPARATE MIXTURES OF HOW TO SEPARATE MIXTURES OF LIQUIDS ?LIQUIDS ?

• PROPERTIES OF SOLIDSPROPERTIES OF SOLIDS

DISTILLATIONDISTILLATION• A method of separating homogeneous A method of separating homogeneous

mixtures of solids in liquids or different mixtures of solids in liquids or different liquids.liquids.

• By boiling and condensing the vapors, the By boiling and condensing the vapors, the mixtures can be separated.mixtures can be separated.

• When a mixture of different liquids is When a mixture of different liquids is heated up the liquid with weaker heated up the liquid with weaker intermolecular attractions will boil first. intermolecular attractions will boil first. The vapors can be condensed to separate The vapors can be condensed to separate the liquids.the liquids.

PressurPressure e CookerCookerit works by it works by increasing the increasing the pressure on pressure on top of the top of the water. The BP water. The BP at higher T at higher T will be higher will be higher and the food and the food cooks faster.cooks faster.

HEAT OF VAPORIZATIONHEAT OF VAPORIZATION

The heat needed to completely The heat needed to completely vaporizevaporize

1 gram of liquid at is BP. 1 gram of liquid at is BP.

SOLIDSSOLIDS

* Have definite shape and volume.* Have definite shape and volume.

* Particles are close together (packed).* Particles are close together (packed).

* Particles have 2 types of movement* Particles have 2 types of movement

rotationrotation and and vibrationvibration in their places in their places

* Particles are arranged in a crystalline * Particles are arranged in a crystalline structure, that is a geometrical pattern that structure, that is a geometrical pattern that repeats itself.repeats itself.

  

AMORPHOUS SOLIDSAMORPHOUS SOLIDS

•Lack an ordered internal Lack an ordered internal structure, don’t have structure, don’t have crystalline structure.crystalline structure.

•Do not have a definite melting Do not have a definite melting point.point.

•Example glass, asphalt, rubberExample glass, asphalt, rubber

SUBLIMATIONSUBLIMATION

• Change of state from solid to gas Change of state from solid to gas without going through the liquid without going through the liquid state. Endothermicstate. Endothermic

• Examples:Examples:

• Dry Ice Dry Ice

• IodineIodine

• Moth ballsMoth balls

DEPOSITIONDEPOSITION

• Phase change from gas directly to Phase change from gas directly to solid.solid.