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CHAPTER 1:CHAPTER 1:SOLIDS, LIQUIDS and SOLIDS, LIQUIDS and

GASESGASES

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Describe the arrangement and properties of solid, liquid & gaseous states of matter using Kinetic Particle TheoryKinetic Particle Theory

Explain the inter- conversion of the 3 states of matter in terms of Kinetic Particle Theory and of the energy changes.

WHAT WE WILL BE WHAT WE WILL BE LEARNINGLEARNING

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WHAT IS MATTER MADE WHAT IS MATTER MADE OF ?OF ? Matter is anything that occupies space and has

mass.

It can exist as a solid, a liquid or a gas.

Recall :

1) Solids

It has a definite shape and volume.

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2) Liquids

It has a definite volume but

no definite shape.

It takes the shape of the container.

3) Gases

It has no definite shape and volume.

It can be compressed and take the

shape of the container.

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KINETIC PARTICLE THEORYKINETIC PARTICLE THEORY

The differences in the properties of solids, liquids and gases can be explained in terms of the Kinetic Particle TheoryKinetic Particle Theory.

This theory states that all matter is made up of tiny particles and are always in constant random motion.

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1) Solids

The particles are packed veryvery closelyclosely together in a fixed, regular patternfixed, regular pattern.

This is why crystals have flat faces, straight edges and sharp points.

The particles attract one anotherattract one another stronglystrongly, thus they are in fixed positions.

This gives solid a definite volume and a definite shape.

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The particles are not free to movenot free to move about but can

only vibrate gently about their fixed positionsonly vibrate gently about their fixed positions.

This is why solid cannot be compressed.

There is very little empty spacevery little empty space between the particles.

This is why solid has high density.

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2) Liquids

The particles are packed closely togetherpacked closely together, but not as close as those particles in solids.

This explains why liquid cannot be compressed.

The particles are held together by forces of attraction between them.

This explains why liquid has a definite volume.

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The particles are not arranged in a fixed patternnot arranged in a fixed pattern and they are free to move about within shortfree to move about within short distancesdistances (in between each other and throughout the liquid).

This is why liquid has no definite shape.

They flow and take the shape

of the container.

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3) Gases

The particles are far apart from each otherfar apart from each other and there is so much space betweenmuch space between each particleeach particle.

This explains why gas can be compressed easily and has low density.

The particles have little attractionlittle attraction for one another.

This explains why gas has no definite volume.

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The particles are not arranged in a fixed patternnot arranged in a fixed pattern and they move about randomlymove about randomly.

They can spread out rapidly to fill up a container.

This is why gas has no definite shape.

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CHANGES OF STATESCHANGES OF STATES

Matter can change its state.

This change in state is reversiblereversible.

Process Changes from … Brief Description

MeltingMelting solid to liquidsolid to liquid Heating causes particles in the Heating causes particles in the solid to vibrate more until they solid to vibrate more until they break free from their fixed break free from their fixed position. position.

Boiling/ Boiling/ Vaporization Vaporization

liquid to gasliquid to gas Heating causes particles in the Heating causes particles in the liquid to gain energy to move liquid to gain energy to move faster and further apart. faster and further apart. Eventually they break away Eventually they break away from surrounding particles and from surrounding particles and form gas.form gas.

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Process Changes from Brief Description

CondensationCondensation gas to liquidgas to liquid Energy is removed from the Energy is removed from the gas particles. This causes gas particles. This causes them to slow down and them to slow down and enter the liquid state.enter the liquid state.

Freezing Freezing liquid to solidliquid to solid Particles lose heat, slow Particles lose heat, slow down and get locked into down and get locked into position.position.

Sublimation Sublimation Solid to gasSolid to gas Solid changes into gas Solid changes into gas without going through the without going through the liquid state. liquid state.

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I) Melting

Melting is a process in which a solid changes into a liquid.

Heat is absorbedHeat is absorbed

during melting.

Melting takes place at

a fixed temperature

called the melting pointmelting point.

HEAT

temperature

stearic acid

water at 100ºC

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Heating curve for changing a Solid to a Liquid

Temperature /oC

Time /min

Melting starts

Melting completes

Solid + Liquid Liquid

Solid

Melting Point of Substance

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II) Boiling

Boiling is a process in which a liquid changes intoa liquid changes into

a gasa gas.

This change in state occurs inside the liquidinside the liquid.

Heat is absorbedHeat is absorbed during boiling.

Boiling takes place at a fixed temperature called

the boiling pointboiling point.

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Heating curve for changing a Liquid to a Gas

Temperature /oC

Time /min

Boiling starts

Boiling completes

Liquid + Gas Gas

Liquid

Boiling Point of Substance

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IV) Sublimation

Sublimation is a process in which a solid changesa solid changes into a gas without passing through the liquidinto a gas without passing through the liquid phasephase.

Heat is absorbedHeat is absorbed during sublimation.

Sublimation takes place at a fixed temperature.

Examples: Dry ice, iodine,

ammonium chloride

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V) Condensation

Condensation is a process in which eithera gas changes into a liquida gas changes into a liquid ora gas changes into a solida gas changes into a solid.

This change in state occurs when a gas is cooled to its boiling point.

Heat is evolvedHeat is evolved during condensation.

Condensation takes place at a fixed temperature numerically equal to its boiling point.

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Cooling curve for changing a Gas into a Liquid

Temperature /oC

Time /min

Condensation starts

Condensation completes

Liquid + Gas

Liquid

Gas

Boiling Point of Substance

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VI) Freezing

Freezing is a process in which

a liquid changes into a solida liquid changes into a solid.

Heat is evolvedHeat is evolved during freezing.

Freezing takes place at a fixed temperature called the freezing pointfreezing point.

Freezing point and melting point have the same numerical value.

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Cooling curve for changing a Liquid into a Solid

Temperature /oC

Time /min

Freezing starts

Freezingcompletes

Liquid + SolidSolid

Liquid

FreezingPoint of Substance