Chapter 13

Essential Questions:

1. What are the nature of gases,

liquids and solids?

2. How can you describe changes

between the states of matter?

3. Predict changes of state based

on physical conditions.

Tiny particles in all

forms of matter are

in constant motion

Kinetic energy(KE):

the energy that a

particle has because

of that motion

•A gas is composed of particles

(atoms or molecules)

•A gas in a container will fill the

container, no matter the shape.

•Uncontained gases diffuse into

space.

•The particles of a gas move

rapidly, in constant random

motion •

•Particles travel in straight

paths until they hit one another

or another object

•All collisions are perfectly

elastic

•KE is transferred from one

particle to another.

•Total KE remains the same.

Caused by the collision

of gas particles with

an object

In a vacuum there are

NO gas particles present

therefore

NO collisions resulting in

NO pressure

Results from the

collisions of air

molecules with

objects

Decreases as you

go up a mountain

because air layer

thins at high

elevations

Used to measure

atmospheric

pressure

Remember:

1 atm = 760 mm Hg = 101.3 kPa = 760 torr

A gas is at a pressure of 1.5 atm.

Convert to kPa and mm of Hg

1.5 atm

1

101.3 kPa

1atm

1.5 atm 760 mm Hg 1140 mm Hg

1 1 atm

151.95 kPa

What does the blue curve

represent?

What does the red curve

represent?

In which sample is the

average KE of the particles

high?

Temperature KE

Absolute zero= 0 K = -273°C

KE = 0

Distribution of KE

in cold water

Distribution of KE

in warm water

Hot water

Liquids and gases

FLOW.. they are

fluids

Liquids have a

stronger

attraction

between particles

Liquids are denser

then gases

Pressure on a liquid

there is very little

effect on the

volume

Liquids and solids are condensed states of matter

•Water molecules at

the surface of the

liquid break away

converting to a gas

or vapor

•Particles vaporize and collide

with wall of lid or containers

• then create vapor pressure

above liquid

•some molecules condense

back into a liquid

Evaporation is a cooling process

(like when you sweat)

because molecules with highest KE (highest

temp) escape, leaving behind the slower

(cooler) molecules.

Measure of the force exerted

by a gas above a liquid

Dynamic equilibrium

rate of evaporation = rate of condensation

Temp of contained liquid

vapor pressure

Measures vapor pressure of a liquid

Temperature @ which vapor pressure of liquid

= external pressure

Normal boiling point: boiling point at 101.3 kPa

(1atm)

Why does it take longer to cook food in water

at high altitudes? Atmospheric pressure decreases with altitude,

decrease pressure,

so water boils at lower temp.

lower temp means longer to cook

What is the boiling point of chloroform at 101.3

kPa?

What is the vapor pressure of ethanol at 40°C?

About 20 kPa

60°C

Less KE

Particles are closer together

Attractive forces between molecules are

stronger (than in liquid or gas)

Melting point: temperature @ which a

solid changes into a liquid

Atoms, ions or molecules arranged in

an orderly repeating 3D pattern

Ionic compounds:

higher melting point

strong attractive

forces

Molecular compounds:

lower melting point

held together by

weaker force

2 or more different molecular forms

of the same element

Ex: Glass, rubber, plastic,

asphalt

i.e. Glass has cooled to a

rigid state without

crystallizing.

Glass is sometimes

called a super-cooled

liquid.

Lack an ordered internal structure

The change of a substance

from a solid to a gas or vapor

with out passing through the

liquid state

The line

between

each phase

represents

when the 2

phases

occur at

equilibrium

Triple point:

the place

where all 3

phases can

exist in

equilibrium

with

one another

Kinetic Energy

Kinetic Theory

Gas Pressure

Vacuum

Atmospheric Pressure

Barometer

Absolute Zero

Evaporation

Vaporization

Vapor Pressure

Boiling Point

Normal Boiling Point

Melting Point

Crystal

Unit Cell

Allotropes

Amorphous Solid

Sublimation

Phase Diagram

Triple Point

Ionic compounds:

higher melting point

strong attractive

forces

Molecular compounds:

lower melting point

held together by

weaker force