Chapter 1Kinetic Particle Theory

1.1 States of Matter• Matter can exist as Matter can exist as a solid, liquid or a gasa solid, liquid or a gas• These three forms of matter are known as These three forms of matter are known as states states

of matterof matter• For instance, For instance, water(liquid)water(liquid) can exist as can exist as

ice(solid) ice(solid) or or water vapour (gaseous).water vapour (gaseous).

Changes of StateChanges of State• Melting, freezing, boiling Melting, freezing, boiling and and condensationcondensation

are example of changes of stateare example of changes of state

1.2 Kinetic Particle Theory

• The kinetic particle theory states that The kinetic particle theory states that all all matter is made up of particlesmatter is made up of particles and that and that these particles are in these particles are in constant, random constant, random motionmotion..

Uses of KPT– Describe the Describe the states of matterstates of matter– Explains the differences in Explains the differences in particles of solid, particles of solid,

liquids, gasesliquids, gases– Explains the Explains the changes of states.changes of states.

1.2 Kinetic Particle Theory

Solid StateSolid State

• Particles of solid are Particles of solid are closely closely packed in orderly mannerpacked in orderly manner

• Vibrate about Vibrate about their their fixed fixed positionspositions

1.2 Kinetic Particle Theory

Why does a solid have a fixed shape and a Why does a solid have a fixed shape and a fixed volume?fixed volume?

• Particles of a solid are heldParticles of a solid are held together by together by very very strong forces attractionstrong forces attraction which which cannot move freely..

• Solid cannot be Solid cannot be compressed since its since its particlesparticles are already are already very close to one another

1.2 Kinetic Particle Theory

Liquid StateLiquid State

• Particles of a liquid are Particles of a liquid are quite quite closely packedclosely packed in in disorderly disorderly patternpattern

• The particles roll and slide over The particles roll and slide over one another.one another.

1.2 Kinetic Particle Theory

Why does a liquid not have a fixed shape?Why does a liquid not have a fixed shape?

• The The force of attraction between the particles are are weaker than those in solid. than those in solid.

• Particles of a liquid does not have a fixed Particles of a liquid does not have a fixed shapeshape

• They can move freely by sliding each other.They can move freely by sliding each other.

1.2 Kinetic Particle Theory

Why does a liquid have a fixed volume?Why does a liquid have a fixed volume?

• Particles of a liquid are farther away from Particles of a liquid are farther away from one another than the particles in a solid.one another than the particles in a solid.

• Particles of a liquid are of a liquid are packed quite closely together.

1.2 Kinetic Particle Theory

Gaseous StateGaseous State

• Particles of a gas are Particles of a gas are spread far apart from one another from one another

• As the As the force of attraction between the particles are between the particles are weak..

1.2 Kinetic Particle Theory

Why does a gas not have a fixed shape and Why does a gas not have a fixed shape and a fixed volume?a fixed volume?

• Particles of a gas have a lot of kinetic energy and are not held in fixed positions.

• They can move about rapidly in any directionThey can move about rapidly in any direction

• Particles can be compressed and move Particles can be compressed and move closer to each other.closer to each other.

1.3 Changes of state and the Kinetic Particle Theory

Melting When a substance changes from a solid to a

liquid, we say that melting takes place.

*What happens to particles of a solid that is heated *What happens to particles of a solid that is heated until it melts?until it melts?

As heat energy is supplied, the particles vibrates, until the vibrations of the particles overcome the attractive forces between them.

1.3 Changes of state and the Kinetic Particle Theory

Melting

Particles begin to break away from their fixed positions. Particles slide over one another it becomes liquid.

1.3 Changes of state and the Kinetic Particle Theory

Melting

A

B

A – B :

Temperature of the solid increases the unit until it reaches point B (Melting point).

Solid begins to melt.

1.3 Changes of state and the Kinetic Particle Theory

Melting

A

B

B-C :

Mixtures of solid and liquid exists here. During melting process, temperature of

substance remains constant even though heating continues. All heat energy taken in by paritcles is used to overcome force

of attraction between particles.

C

1.3 Changes of state and the Kinetic Particle Theory

Melting

A

BC-D

All solids has melted and temperature of liquid rises as heating

continues.

C

D

1.3 Changes of state and the Kinetic Particle Theory

Freezing When a substance changes from a liquid to a

solid, we say that freezing takes place.

*What happens to particles of a liquid that is cooled *What happens to particles of a liquid that is cooled until it freezes?until it freezes?

Particles lose kinetic energy and begin to move more slowly. When the temperature is low enough, some

particles start to settle into fixed positions. Finally, all particles settle into fixed positions. Substance now is

a solid

1.3 Changes of state and the Kinetic Particle Theory

Freezing

P

Q

P – Q :

Temperature of liquid drops until it reach point Q, freezing point of napthalene. At

point Q, liquid starting freezes.

1.3 Changes of state and the Kinetic Particle Theory

Freezing

P

R

Q - R:

During the freezing process, the temperature of substance remains the same even through cooling continues.

Q

1.3 Changes of state and the Kinetic Particle Theory

Freezing

P

R

R - S:

At point R, substances solidified. Temperature of solid continues to drop as

it’s cool.

Q

S

1.3 Changes of state and the Kinetic Particle Theory

Boiling As the liquid is heated, the particles gain kinetic

energy and start to move faster.Eventually, the particles have enough energy to

overcome the forces holding them togetherThey spread far apart and move rapidly in all

directions. The substance now is a gas.

1.3 Changes of state and the Kinetic Particle Theory

Boiling How does the temperature of a liquid change

when it boils?When liquid is heated, its

temperature increases till its boiling point is reached.

Here, it boils & changes into a vapour. The temperature

remains constant till all liquid has boiled off

1.3 Changes of state and the Kinetic Particle Theory

Evaporation Evaporation occurs because some particles have

enough energy to escape as a gas from the surface of the liquid.

Liquids that evaporate quickly at room temperature are called volatile liquids.

Petrol and perfume are examples of volatile liquids.

1.3 Changes of state and the Kinetic Particle Theory

Condensation Heat energy is given out during Condensation

As the temperature drops, the gas particles lose energy and move more slower.

Eventually, the movement of particles become slow enough for the gas to change into a liquid.

1.3 Changes of state and the Kinetic Particle Theory

Sublimation When a substance sublimes, it changes directly

from a solid to a gas.

Dry Ice, Solid iodine, ammonia chloride sublimes.

A substance sublimes because the forces between the particles in liquid state are too weak to remain in the state.