18.1b Notes18.1b NotesStates of Matter & Phase States of Matter & Phase

ChangesChangesSupplement to Chapter 18Supplement to Chapter 18

ObjectiveObjective

Describe the phase and energy changes Describe the phase and energy changes associated with phase changes. associated with phase changes.

States of MatterStates of MatterSolids Liquids Gases

Mass

Volume

Shape

Energy

SolidsSolids Solid – holds a particular shape & Solid – holds a particular shape &

has definite volumehas definite volume Orderliness of particlesOrderliness of particles

Mass: Mass: definitedefinite Volume: Volume: definitedefinite Shape: Shape: definitedefinite Energy: Energy: lowlow

LiquidsLiquids Liquid – does not hold own shape Liquid – does not hold own shape

but does occupy a definite volumebut does occupy a definite volume Flows freely and takes shape of Flows freely and takes shape of

containercontainer Mass: Mass: definitedefinite Volume: Volume: definitedefinite Shape: Shape: shape of containershape of container Energy: Energy: mediummedium

GasesGases Gas – no definite shape or Gas – no definite shape or

volumevolume Expands to fill available volume Expands to fill available volume

of containerof container Mass: Mass: definitedefinite Volume: Volume: can be compressedcan be compressed Shape: Shape: shape of containershape of container Energy: Energy: highhigh

States of MatterStates of MatterSolids Liquids Gases

Mass Definite Definite Definite

Volume Definite Definite Can be Compressed

Shape Definite Shape of container

Shape of Container

Energy Low Medium High

PlasmaPlasma gas-likegas-like made of atoms that have been made of atoms that have been

ripped apart into ions and electronsripped apart into ions and electrons the sun is made of plasma, as is the sun is made of plasma, as is

most of the matter in the universemost of the matter in the universe Plasmas are usually very hot, and Plasmas are usually very hot, and

you can keep them in magnetic you can keep them in magnetic bottlesbottles

Changes in StateChanges in State A transition from one state of matter A transition from one state of matter

to anotherto another Melting: solid to liquidMelting: solid to liquid Freezing: liquid to solidFreezing: liquid to solid Vaporization: liquid to gasVaporization: liquid to gas

Boiling: throughout the liquidBoiling: throughout the liquid Evaporation: surface onlyEvaporation: surface only

Condensation: gas to liquidCondensation: gas to liquid Sublimation: solid to gasSublimation: solid to gas

Changes in StatesChanges in States

Solid

Liquid

Gas

Sublimatio

n

Melting

Freezin

g

Conden

satio

n

Vaporizatio

n

Changing States - MeltingChanging States - Melting

Solid becomes a liquidSolid becomes a liquid

Melting point = temperature at which a Melting point = temperature at which a solid begins to meltsolid begins to melt

Heat of fusion = the amount of energy Heat of fusion = the amount of energy required to change 1 kg of a substance required to change 1 kg of a substance from a solid to a liquid at its melting point from a solid to a liquid at its melting point

FreezingFreezing

Liquid becomes a solidLiquid becomes a solid

Heat of fusion is also the energy released Heat of fusion is also the energy released when a liquid freezeswhen a liquid freezes

The attractive forces are strong enough The attractive forces are strong enough that the particles form an ordered that the particles form an ordered arrangementarrangement

VaporizationVaporization

Liquid becomes a gasLiquid becomes a gas

Evaporation = when vaporization occurs at Evaporation = when vaporization occurs at the surface of a liquid the surface of a liquid Causes the temperature of the liquid to Causes the temperature of the liquid to

decreasedecrease

BoilingBoiling

Second way a Liquid becomes a gasSecond way a Liquid becomes a gas

Occurs throughout the liquid, not just on Occurs throughout the liquid, not just on surfacesurface

Boiling point = temperature at which the Boiling point = temperature at which the pressure of the vapor in the liquid is equal to pressure of the vapor in the liquid is equal to the external pressure acting on its surfacethe external pressure acting on its surface

The heat of vaporization is the amount of The heat of vaporization is the amount of energy required for 1 kg of the liquid at its energy required for 1 kg of the liquid at its boiling point to become a gasboiling point to become a gas

CondensationCondensation

Gas changes to a liquidGas changes to a liquid

The heat of vaporization is also the amount The heat of vaporization is also the amount of energy released during condensationof energy released during condensation

In-class assignment/HomeworkIn-class assignment/Homework