61 02898 SAVic1 Ch02catalogimages.johnwiley.com.au/.../SAVic1_Ch02.pdf · 2008-01-20 · 24 Science Alive 1 for VELS Change of state ater is the only type of matter that exists in

• What matter is• Types and properties of matter• How particles move in solids, liquids and gases

Making smokeIt’s used at rock concerts, in

nightclubs and even at weddings.

The effect created when lights flash

through the smoke from a smoke

machine can be quite spectacular.

But what is the smoke made from?

It certainly doesn’t smell like the

smoke that is created by fire.

Some smoke machines use the

carbon dioxide we breathe out to

help create the smoky haze. That’s

right, carbon dioxide! But the

carbon dioxide used to make the

‘smoke’ is different from the stuff

we breathe out. Smoke machines

use solid carbon dioxide, also

known as dry ice. When water is

added to the solid carbon dioxide, it

quickly changes into a gas. The dry

ice and the carbon dioxide gas are

very cold. They cool the air around

them so much that tiny droplets

of water form in the air. The tiny

droplets of water look like clouds,

or smoke.

1 Are clouds made up of liquid

or gas?

2 Is slime a

solid or

liquid?

3 Are there other materials that are

hard to group as a solid, liquid or

gas?

4 Do all solids form a liquid before

they change into a gas?

22Science Alive 1 for VELS

States of matterverything around you is made of matter. Anything that has mass and takes up space is matter. The air we breathe, the water we drink and the food we eat are

all different types of matter. But air, water and food are very different. One important difference between these items is their state. The three main states of matter are solid, liquid and gas.

Solids do not usually flowMost solids are too rigid to flow.

Substances such as sugar, which

are made up of many small solid

pieces, can be poured.

Gases flowLike liquids, gases

flow from one

container to another.

The gas from the

helium bottle flows to

the balloon through a

tube. It is often hard to

see gases flow because

many of them are

colourless.

Gases can be compressedGases can be squeezed so they

take up less space (compressed).

The gas inside the helium bottle

is compressed. It expands when

it leaves the bottle and fills the

balloons. Solids and liquids

cannot be compressed.

Gases change shapeGases fill the entire container they

are in. The helium gas in balloons

changes shape depending on the

shape of the balloon. The helium fills

every part of the balloon.

The volume of gases changesGases expand to fill the

containers they are placed

in. Gases do not have a

fixed volume.

Solids have a constant shapeSolids have a fixed shape

and change shape only

when a force is applied.

The force applied to both

ends of this bar by the

circus strongman causes

the bar to bend.

232. Solids, liquids and gases

Liquids change shapeA liquid’s shape

changes to fit the

container it is in. The

shape of the lemonade

in these glasses depends

on the shape of the

glass. Liquids at rest

have a flat surface.

Liquids have a fixed volumeThe liquid from the jug can

be poured into several

glasses. The total amount of

space taken up in the glasses

equals the amount that was

originally in the jug.

Liquids flowLiquids can be

poured from

one container

to another.

When the

container is

full, it

overflows.

Solids have a fixed volumeIf you move a solid from container

to container, the amount of space it

takes up (volume) is the same.

Investigating solids, liquids and gases

You will need:

a piece of dowel large plastic syringewater plasticine salt sponge.

• Copy the following table.

• Insert the dowel into the syringe. Press down on the plunger.

1. Can the dowel be compressed?

• Draw some water into the syringe. Put your finger over the end of the syringe and press down on the plunger.

2. Can water be compressed?

• Draw some air into the syringe. Put your finger over the end of the syringe and press down on the plunger.

3. Can air be compressed?

• Complete the remainder of the table by looking closely at the dowel and water, and by reading the captions on the circus scene.

• Investigate the properties of plasticine, salt and sponge.

4. Classify each of the three materials as a solid, liquid or gas.

5. Which materials did you have trouble classifying? Why?

Property Solid (dowel) Liquid (water) Gas (air)

Fixed shape

Fixed volume

Able to be compressed

REMEMBER1. What properties do we use to

classify materials into the three states?

2. Which state/s of matter: (a) can be compressed? (b) can flow?

THINK3. Classify each of the following

items as a solid, liquid or gas.Oxygen Talcum powder Glass Vaseline Oil HoneyWood Sand

4. Why is a bicycle frame made of solids?

5. Why are bicycle tyres filled with air?

OBSERVE6. Look carefully at the circus

scene on the left.(a) List as many solids,

liquids and gases as you can find.

(b) Find one example of a substance that can change from one state to another.

� le

arn

ing I CAN:

name the three states of matter

describe the properties of the three states of matter

classify materials as solids, liquids or gases.


Change of stateater is the only type of matter that exists in all three states at normal air temperatures. Solid water (ice) is found in the form of icebergs and

glaciers. Ice also falls from the sky during hailstorms. Liquid water (water) makes up our rivers, lakes and oceans. Water in the form of a gas (water vapour) is found in the air.

W

Sublimation occurs when a solid turns into a gas without first turning into a liquid.A change from gas to solid, without going through the liquid stage, is also calledsublimation. Iodine, diamond and dry ice(solid carbon dioxide) are substances that sublime.

Frozen carbon dioxide (dry ice) changes directly from a solid to a gas (sublimation).

CondensingCondensation is the

opposite of evaporation. If

a gas comes into contact

with a cold surface, it can

turn into a liquid.

MeltingThe change of state from solid to liquid is called

melting. A solid melts when heat is transferred to it.

The melting point of water is 0 °C.

BoilingDuring boiling, the change from liquid to gas

(evaporation) happens quickly. The change is

so fast that bubbles form in the liquid as the gas

rises through it and escapes. During boiling,

the entire substance is heated. A liquid remains

at its boiling point until it has all turned into a

gas. The boiling point of water is 100 °C.

EvaporatingEvaporation occurs when a liquid changes to

a gas. When water evaporates at temperatures

less than 100 °C, it forms water vapour. When

it evaporates at temperatures greater than

100 °C, it forms steam. Water vapour and

steam cannot be seen.FreezingThe change of

state from a

liquid to a

solid is called

freezing. A

liquid turns

into a solid

when heat is

transferred

away from it.

Water freezes

at 0 °C.

Melting and boiling points of some common substances

SubstanceMelting

point (°C)Boiling

point (°C)

Water 0 100

Table salt 804 1413

Petrol −57 126

Oxygen −219 −183

Aluminium 660 1800


Changing the boiling point of water

You will need:

• Copy the following table.

• Set up the equipment as shown below. Put on your safety glasses.

• Measure 100 mL of water with the measuring cylinder and pour it into the beaker.

• Measure the starting temperature of the water (time = 0 min).

• Light the Bunsen burner and place it under the beaker. Measure the temperature of the water every minute for 10 minutes. Record your observations in the table.

• After 10 minutes, turn off the Bunsen burner and allow the equipment to cool.

• Repeat the above steps with 100 mL of water with two teaspoons of salt stirred in, then 100 mL of water with two teaspoons of sugar stirred in, and lastly with 80 mL of water with 20 mL of vinegar stirred in.

1. Draw a line graph of your results. Use a different coloured line for each water mixture. Plot time on the horizontal axis and temperature on the vertical axis.

2. How can you tell when the water has reached its boiling point?

3. Is there any part of the graph that shows the liquid has reached its boiling point?

4. What effect does adding substances to the water have on its boiling point?

5. What would happen to the temperature of each water sample if you continued to heat it past the 10-minute mark?

Time (min) 0 1 2 3 4 5 6 7 8 9 10

Tem

pe

ratu

re (

°C) Tap water

Salt water

Sugar water

Vinegar water

Retort stand

Boss head

Thermometer

Beaker

Gauzemat

Tripod

Bunsen burnerBox of

matches

Clamp

Heatproof mat

water

Bunsen burner

safety glasses

2 × 250 mL beakers

heatproof mat

thermometer

salt

matches

retort stand

sugar

tripod

boss head and clamp

vinegar

gauze mat

teaspoon

100 mL measuring cylinder.

REMEMBER1. List the three states of

matter.

2. Is heat transferred to a

liquid or from a liquid

during freezing?

3. What is the melting point

of ice?

4. What is the boiling point

of water?

5. Copy and complete the

following flow diagram:

THINK6. What is the difference

between evaporation and

boiling?

7. Describe a method for

changing the boiling point

of water.

INVESTIGATE8. At what temperature is:

(a) oxygen a solid?

(b) aluminium a liquid?

9. Find out how the melting

point of water can be

changed.

Liquid

Solid Gas

Evaporation

Go toworksheet 1.5

� le

arn

ing I CAN:

list the processes that result in a change of state

describe the relationships between each state

explain the difference between evaporation and boiling.


The particle modelll matter is made up of tiny particles. If you could shrink down to microscopic

size and watch these particles, you would see that the particles behavedifferently depending on whether the substance they make up is a solid, liquid or gas. To help explain this different behaviour, scientists have developed a model called the particle model of matter.

A

Models help people understand complex ideas, such as how matter behaves. As new clues about matter have been discovered, the models have been improved. The basis of the particle model is that:• All matter is made up of small particles.• Particles are always moving.

• Particles are held together by bonds that vary in strength.

• As particles are heated, they move more quickly. When the particles are cooled, they move more slowly.

Particles in a liquidThe particles in a liquid are close together. So, there is no

room for compression between the particles in a liquid. The

particles are also held tightly by bonds, but not in the same

rigid structure as solids. This gives liquids their fixed

volume, but allows the particles to roll over each other.

This rolling allows liquids to flow. The

movement of the particles explains

why liquids take the shape of their

container. The particles roll over each

other until they fill the bottom of the

container.

Particles in a solidSolids cannot be compressed

because the particles inside them

are held closely together. There is

no space between them. Bonds also

hold the particles tightly together in

a rigid crystal-like structure. This gives solids their fixed

shape and constant volume. The particles in solids cannot

move freely; they vibrate in a fixed position. This means that

solids are unable to flow.

Particles in a gasThe forces between the particles in a gas are very weak.

The particles are in constant motion. This means that

gases have no fixed shape or volume. There are large

spaces between the particles. The spaces allow

the gas to be compressed. A gas can flow and

diffuse easily since its particles are always

moving. Gas particles have much more energy

than solid and liquid particles. They move

around and collide with other particles

and the walls of the container they

are in.


DiffusionDiffusion is the spreading of one substance through another. The spreading occurs because the particles of each substance become mixed together. The movement of the particles in liquids and gases makes diffusion possible. As the particles in a gas move faster than in liquids, diffusion happens faster in a gas. Particles are not free to move in a solid, so diffusion cannot occur at all.

The spreading starts in an area where there is a concentration of one of the substances. The particles keep mixing through until they are evenly spread through each other. Air deodoriser

Crystal

Water

Beaker

Holdstraw

Investigating diffusion

You will need:

500 mL beaker

water

straw

potassium permanganate crystals

fragrant spray

protective mat

safety glasses.

• Using the straw as a

guide, put a crystal of

potassium permanganate

in the bottom of a beaker of

water. Remove the straw

and record your

observations.

1. Draw a diagram of the

movement of the potassium

permanganate through the

water.

• Release some of the fragrant spray in one corner of

the classroom. Move away and observe by smell.

2. How do you think the fragrant spray moved

through the air?

3. This experiment shows diffusion in a liquid (water)

and diffusion in a gas (air).

(a) Which state diffuses faster — liquid or gas?

(b) Why do you think this is?

� le

arn

ing I CAN:

describe the particle model of matter

describe how the particles move in each of the states: solid, liquid and gas

explain how diffusion occurs in liquids and gases.

REMEMBER1. What is the basis of the particle model?

2. What is diffusion?

3. Give an everyday example of diffusion at

work.

4. Copy and complete the table at right.

THINK5. Why do solids have a fixed shape?

6. Why can gases be compressed?

7. Why do gases fill their containers?

8. When you pour cordial into water, the two

liquids slowly mix together even though

you don’t stir them. Explain how this

happens.

Property Solid Liquid Gas

Particle arrangement

Force of attraction between particles

Movement of particles

Ability to diffuse


Change of state and the particle model

magine a very cold day. On days like this, you probably sit inside without moving around too much. As the weather gets warmer, you start to move around a little

more. On warm, sunny days, you probably have a lot more energy. On these days, you might feel like moving about more. Much like you, the particles inside matter also change the way they move when they are heated or cooled.

Changing stateA change of state involves the heating or cooling of matter. As a substance is heated, energy is transferred to it. When a substance cools, energy moves away from

it to another substance or to the environment. The change in energy causes the particles in the substance to move at different speeds.

Solid When a solid is heated, its

particles start to move more

quickly. The increased

movement of its particles

makes the solid expand.

MeltingAs more heat is transferred to the

solid, its particles vibrate more

violently. Eventually the particles

move so much that the bonds

holding them in their fixed positions

break. The particles start to roll

over each other. Melting continues

until the entire solid becomes a

liquid.

LiquidAs a liquid is

heated, its

particles move

and roll over

each other

faster and

faster. The

liquid begins

to expand.

BoilingIf the liquid continues to be heated,

the particles will eventually have

enough energy to break the bonds

holding them together. The particles

can break away from the liquid and

begin to move around freely. This

process is called boiling. Boiling

continues until the entire

liquid becomes a gas.

GasAs in solids and liquids, the particles

in gases move faster and faster when

they are heated. The increased

movement of the particles means that

they take up more space and the gas

expands. If the gas is heated in a

closed container, the increased

movement of the particles means that

they collide more often with the sides

of the container and with each other.


Foggy mirrorsHave you noticed how the mirror in the bathroom ‘fogs up’ after a hot shower? The ‘fog’ is actually

formed when water vapour that evaporates from the hot water cools down.

Invisible gasWater vapour forms

when particles in

the hot water gain

enough energy to

escape and become

a gas. You can’t see

water vapour. The

particles in the

water vapour move

around freely. They

have more energy

than the particles

in the liquid water.

Fog in the airSome of the energy of the particles

in the water vapour is transferred

away from the vapour to the air.

The transfer of energy leaves the

water vapour with less energy —

so much less energy that

its particles slow down.

The transfer of energy

away from the water

vapour means it cools

down and turns into tiny

droplets of water. These

tiny droplets form

clouds. This process is

called condensation.

Fog on the mirrorThe energy from some of

the water vapour is

transferred to the cold

mirror. This results in the

water vapour condensing on the

mirror.

REMEMBER1. What happens to the movement of particles as

a substance changes from a solid to a liquid?

2. What happens to the movement of particles as

a substance changes from a gas to a liquid?

3. Why do substances often expand when they are

heated?

THINK4. The steel rails used in train tracks are placed

end to end in a line to form each side of a train

track. Gaps are left between the steel rails. Why

do you think these gaps are left between the

rails? Use the word ‘expansion’ in your

explanation.

5. What is the relationship between the amount of

energy the particles in a substance have and the

state (phase) of the substance?

6. Explain why many substances contract when they

are cooled.

TEAMWORK7. As a class, make a list of structures and substances

around your home that undergo expansion and

contraction. Divide your list into things that expand

and things that contract.

Chec

kpoint

✓ le

arn

ing I CAN:

describe what happens to the particles in a substance as it changes state

explain why substances expand when heated.


Solids at workt’s easy to see why solids have a fixed shape — the particles are so tightly packed that they can only vibrate on the spot. However, it is possible to force solids to

change shape! For example, heating, hammering, stretching and squeezing all affect the particles in a solid and cause it to change shape.

Because solids sometimes change shape, architects and engineers must take the expansion, contraction and flexibility of materials into account when designing structures. For example, even though the Rialto Tower in Melbourne (the highest building in the Southern Hemisphere) is made of solids like concrete and steel, the top of it still moves up to 50 centimetres back and forth.

Expanding solidsAll solids expand when heated, just as metal does when heated by a blacksmith. This can be both useful and a problem.

Gaps must be left in railway lines and bridges to allow the metal to expand on hot days. Without the gaps, the railway lines would buckle out of shape.

Fire alarms and fridge thermostats use a special strip made of two layers of metal. The strip is called a bimetallic strip. When heated, one metal (copper) expands more than the other (invar). In a fire alarm, the strip bends up when hot and completes the electric circuit, turning on the siren.

Expansion gap Expansion gap

Battery

Invar

Copper

Siren

Bimetallic stripbends up whenheated.

BlacksmithingMany solids,

especially metals, can have their shape changed. To do this, we take advantage of the properties of the solid. A blacksmith can take a block of metal and shape it into something useful.

A blacksmith makes use of the properties of metal to shape it.

The blacksmith

heats up metal in a

fire to make the

particles vibrate

more quickly.

A blacksmith uses tools like hammers to hit the

softened metal and reshape it. The particles are moved

around in the metal into new

positions to make

a new shape.

When the particles vibrate faster,

the bonds between them weaken,

making the metal softer. The

vibrating particles push each

other further apart. This means

they also take up more space, so

the metal expands.


� le

arn

ing I CAN:

describe the properties of solids in terms of particles and bonds

describe, in terms of particles, why solids expand when heated

match the properties of solids to their uses.

A solid selectionThere are many different solids. Different solids are used for different things depending on their properties. Some examples are given in the table below.

Solid Properties Uses

Concrete Hard, strong, long lasting Paths, buildings, walls

PET (plastic) Soft, flexible, strong, transparent

Drink bottles

Ceramics Waterproof (if glazed), heatproof, strong, hard

Plant pots, kitchen tiles, roof tiles, heat tiles on space shuttle

Copper Easily shaped and stretched, unreactive, excellent conductor of heat and electricity

Electrical wiring, pots and pans, pipes for plumbing

Aluminium Strong, easily shaped and stretched, light, unreactive

Aircraft, bicycles, engines, drink cans

Diamond Very hard, transparent, strong Cutting tools, jewellery

Wood Hard, strong, attractive, flammable

Building, furniture, fuel in fireplaces

A solid activity

You will need:

ball and hoop apparatus

Bunsen burner

tongs.

• Try to pass the ball through the

hoop at room temperature.

1. Did it fit through the ring when

it was cool?

• Heat the ball over the Bunsen

burner and use the tongs to

carefully try to drop the ball

through the hoop while it is

hot.

2. Did the ball fit when it was

hot?

3. Use the particle model of

matter to explain why this has

occurred.

4. If the ball did not fit at room

temperature, how could you

make it fit?

REMEMBER1. What happens to the

particles in a solid when

they are heated?

2. What properties of a solid

allow a blacksmith to

shape metals?

3. What is a bimetallic strip

and what is it used for?

4. Draw a labelled diagram

to show how a bimetallic

strip would bend when

heated.

THINK5. Explain, in terms of

particles and bonds, why

the concrete and steel in a

skyscraper can bend.

6. Think of two other

structures where gaps

need to be left for

expansion to occur on hot

days.

7. Draw a diagram to show

how power lines are hung

with some slack between

the poles. Redraw the

diagram to show how they

would hang on a hotter

day.

8. For each material in group

(a), select a matching

property from group (b)

and a use from group (c).

(a) Marble, iron, gold,

polystyrene

(b) Easily shaped and

attractive, light and

soft, strong and hard,

hard and attractive

(c) Statue, jewellery,

packaging, horseshoe

Go toworksheet 1.6


Liquids atwork

ave you ever noticed how many liquids you use every day? You may be surprised

to know that liquids are everywhere! We depend on liquids in many ways because they have special properties that solids and gases don’t have.

Hydraulic jacks use

liquids (oil) to make

it easier to lift

heavy objects.

Moving the jack

handle pushes

on the liquid in

the hose. Liquids

cannot be

compressed, so

the push on the

liquid is passed

along the length of the

hose to a piston that causes the car to

lift a short distance.

The particles in oil are large and they can slide past

each other. This makes oil slippery. Slippery liquids

are called lubricants. Lubricants are used between

moving parts to reduce wear.

Humans are made mostly of

water. Most chemicals in our

bodies are dissolved in water.

The water is used to transport

substances around our body.

Chemical reactions inside us

take place in water.

The particles in water are small. They can

fit between the tiny gaps in the material of

our clothes and carry

dirt away.

Many things dissolve or float in water. This means that

water can be used to carry away much of our waste.

Water can be moved using a siphon. Because

water particles stick together (cohesion) they can pull each other along through the

hose with a bit of help from

gravity.

When you place a

thermometer in your

mouth, the liquid

inside it gets hotter. As

the liquid gets hotter,

the particles inside it

move around more,

taking up more space.

The liquid expands

and moves up the tube,

showing a higher

temperature.

Water is carried in pipes.

This is possible because water

cannot be compressed, and the

particles push each other

along under pressure.

What about water?

You will need:

water

500 mL beaker

paperclip or needle.

• Make a paperclip or a steel needle float on

water.

1. Record how you got the paperclip to float.


The water in the glass goes up at the edges. This curving of the water’s surface is called a meniscus. The particles in water are attracted to the glass. This is called adhesion. When we measure water in a measuring cylinder, we take the reading from the bottom of the meniscus.

Many fuels are liquids. The particles contain stored energy that can be released by burning in an engine.

Water is used in an evaporative cooler. Hot air from the room passes over the water. The liquid water evaporates into a gas using the heat from the air. Energy from the air has been transferred to the water. The air is now cooler and is blown back into the room by a fan.

Oils are used for cooking. Oils have large, heavy particles. They boil at higher temperatures than water, which means we can cook foods at temperatures higher than 100 °C.

Liquids expand when heated. When the liquid gets hotter, the particles move faster and take up more space. This is why a hot water system has an overflow pipe — to release the pressure.

• Water has surface tension. The particles on the surface of the water pull

towards each other. The pull is strong enough to make the surface ‘firm’.

The ‘firmness’ is called surface tension.

2. Use this information to explain why some insects can walk on water.

3. Why does it hurt if you do a ‘bellywhacker’ at the pool?

• Design an experiment to investigate what type of object can float using

only the surface tension of the water. You may test shape, size, weight or

type of material.

• Test some other liquids to see if their surface tension is stronger or weaker

than water.

REMEMBER1. What is cohesion?

2. How does an evaporative

cooler work?

3. What makes a lubricant like

oil slippery?

4. Explain how a hydraulic jack

works.

5. What property of liquids

does a thermometer use?

6. Why do liquids expand

when heated?

THINK7. How are the particles in oil

different from those in

water?

8. Explain why a liquid cannot

be compressed.

9. Why can’t gases be used in

hydraulic machinery?

10. What does it mean if a

chemical can dissolve in

water?

DESIGN11. Design a machine that uses

hydraulics to make a job easier.

INVESTIGATE12. Design an experiment to

test one or two of the

following things about a

siphon.

• At what maximum length

will a siphon hose stop

working?

• How does the width of the

hose affect the amount

siphoned?

• How does the height of

the higher container affect

the speed of siphoning?

• What is the best angle for

the siphon hose?

� le

arn

ing I CAN:

relate the uses of different liquids to their properties

describe the differences between the properties of liquids and those of solids and gases.


Gases at workhe firefighter burst through the doors just in time, pointed the extinguisher at the electrical fire and pressed the trigger.

A huge burst of carbon dioxide gas came squirting out of the nozzle, putting out the flames.’

‘T

CompressibilityThe carbon dioxide in the story above could be used in this way only because huge amounts of it can be compressed, orsqueezed, into a container. Gases can be compressed becausethere is a lot of space between the particles. Gases compressedinto cylinders are used for barbecues, scuba diving, natural gas in cars, and aerosol cans.

ExpansionHot-air balloons work on the idea that gases expand when heated. The particles in the heated gas move about more and take up more space. This makes each cubic centimetre of hot air in the balloon lighter than each cubic centimetre of air outside the balloon, so it rises, taking the balloon with it.

Fighting fire

1. Gases, including

carbon dioxide, have

lots of space between

their particles.

2. The carbon

dioxide is

compressed into

the cylinder.

The particles

are squashed

closer together.

3. The carbon dioxide particles

are now under increased pressure.

This means that the particles in

the gas collide frequently with the

walls of the cylinder. The particles

push outwards on the walls of the

cylinder. The particles are trying

to escape, but are held in by the

container.

4. When the nozzle is opened, the

pressure forces the carbon dioxide gas

out very quickly through the opening.

5. The particles of gas

quickly spread out over

the fire. The gas smothers

the fire, stopping oxygen

from the air getting to it.

Fires cannot burn

without oxygen, so the

fire goes out.


� le

arn

ing I CAN:

explain what happens to a gas when it is compressed or when it expands

explain how a fire extinguisher works

relate the uses of different gases to their properties.

Fizzing drinksAll carbonated soft drinks contain carbon

dioxide gas. The gas is dissolved in the liquid under high pressure. The gas stays dissolved in the liquid as long as the pressure inside the can is higher than outside the can. When the can is opened, it is de-pressurised and the carbon dioxide starts rising to the surface (because it is lighter than the liquid). In its hurry to escape, the carbon dioxide often pushes the top layer of liquid out as well, causing it to fizz and spill.

Well-known gasesThere are many gases we use for different purposes. Here are some of the more well-known ones.

Famous gas Use Property

Neon Neon lights Absorbs electrical energy and turns it into light

Helium Party balloons, blimps

Lighter than air

Methane (in natural gas)

Cooking, heating Flammable

Argon Fluorescent lights Absorbs electrical energy and turns it into light

Ozone Cleaning water in pools and spas

Highly reactive; kills bacteria

Nitrous oxide (laughing gas)

Anaesthetic Affects nervous system in humans

REMEMBER1. Why can gases be compressed?2. What happens to a gas that is heated? 3. Explain how a carbon dioxide fire extinguisher works.

THINK4. Draw a diagram of a gas before and after heating

to show what happens to the particles.5. Why do aerosol cans have ‘Do not dispose of in

fire’ printed on the can?6. Explain which would last longer: a scuba diver’s

tank filled with compressed air or one filled with air at normal pressure.

7. Explain what would happen to the pressure in a car tyre after it has been driven on a hot road, and then parked on some cool grass.

INVESTIGATE8. Many gases, including oxygen, nitrogen, chlorine

and hydrogen, have important uses. Choose one of these gases and find out what it is used for and why.

9. Find out what gases are found in the air and how much of each gas there is.

10. Many gases in the air are pollutants put there by humans. Find out about what problem one of the following gases causes to the environment: sulfur dioxide, chlorofluorocarbons (CFCs), nitrogen dioxide, or ozone.

Getting spaced out

You will need:small balloon string rulerlarge beaker warm water cold water or fridge.

• Blow up the balloon until it is firm.

• Measure the circumference of the balloon with a piece of string and record your results in a table.

• Put the balloon in warm water for 10 minutes and re-measure the circumference.

1. Did the balloon expand or contract?

• Put the balloon into the cold water or a fridge for 10 minutes and measure the circumference of the balloon again.

2. Did the balloon expand or contract?

3. In terms of particles, explain what happened when the balloon was heated and cooled.

Go toworksheet 1.7


Check and challengeSolids, liquids and gases Te

st

yourself

The particle model of matter

1. List the four principles behind the particle

model.

2. What is matter?

Properties of solids, liquids and gases3. Copy and complete the table below to summarise

the properties of solids, liquids and gases.

4. Fully explain the process that is occurring in the

following diagrams.

5. Complete the following diagram by labelling the

arrows:

Property Solid Liquid Gas

Has a fixed shape

Has a fixed volume

Able to flow

Able to diffuse

Able to be compressed

Space between particles

Particle movement

Bonds between particles

Solid Liquid Gas→←

→←

6. (a) What happens to the movement of particles in a

substance when it changes state from a solid to a

liquid?

(b) What happens to the bonds between the particles

in this process?

7. In which state — solid, liquid or gas — do the

particles have the:

(a) most energy?

(b) least energy?

8. Describe two ways to change the speed at which

particles move in a liquid.

9. Draw a diagram to show what happens to the

particles inside a balloon that is placed in the

refrigerator.

10. Describe the difference between boiling and

evaporating.

11. Explain how and why water forms on the outside of a

cold soft-drink bottle on a warm day. Use diagrams to

help with your explanation.

12. (a) What does sublimation mean?

(b) Give an example of a substance that sublimes.

13. Which of these diagrams (A, B or C) correctly shows a

solid after expanding?

Original solid

A B C


Matching the properties of a substance to its use 14. (a) Copy out this table and rewrite it to correctly

match the substances to their properties and

uses.

(b) State whether the substance would be a solid,

liquid or gas.

15. Suggest a reason why bridges have gaps between the

blocks they are constructed from.

16. Decide whether each of the following statements is

true or false. If the statement is false, explain why.

(a) The compressibility of gases makes carbon

dioxide useful in a fire extinguisher.

(b) Gases expand

when cooled.

(c) Water particles

stick together.

This is called

adhesion.

(d) Solids are hard

because the

particles are

close together.

(e) Fuels have

energy stored

in the bonds

between

particles.

Name of substance Property Use

Solid, liquid or

gas?

Air Waterproof, hard, strong

Horseshoe

Tin Particles able to mix easily with other particles

Balloon

Neon Particles absorb energy and turn it into light

Sign, light

Oil Hard, strong Driveways

Iron Hard, strong, easily shaped when heated

Lubricant

Concrete Particles slip past each other

Roofing

Cars1. A car is constructed from

solids, liquids and gases.

(a) List the solids, liquids and gases found in

a car.

(b) Why don’t cars have solid tyres?

(c) Why don’t cars use solid fuel?

(d) How could cars that work on gas carry enough

fuel?

2. Rob pumped up his tyres on a cold day. A week later,

the weather warmed up and Rob decided to go for a

long drive. He noticed that the pressure inside the

tyres had changed from when he had first pumped

them up. Would the tyre pressure have increased or

decreased after the long drive? Explain fully.

3. Separate the following substances into solids, liquids

and gases.

Gold Fairy floss Helium

Slime (see page 21) Glass Milk

DVD Kitchen sponge Neon

If you need help, try researching in the library or on

the Internet.

Designer substances4. Imagine you are a scientist in charge of developing

new materials. The Australian Space Agency has

approached you because they need a new substance

to coat the outside of the space shuttles they are

designing. The substance must be:

• able to withstand the heat of the shuttle re-entering

the Earth’s atmosphere

• flexible enough to bend when the wings of the

shuttle bend

• strong enough to stand the vibration of take-off,

landing and other movement

• light enough to be part of a flying spacecraft

• resistant to chemical attack

• able to reflect the solar radiation in space.

Your task is to design the coating for the space

shuttle. Include:

(a) whether it will be solid, or an innovative

liquid or gas coating. It could be a

combination of these in layers or as

a mixture.

(b) how the coating of

substances will work to meet

the criteria from the Australian

Space Agency. This will include the

properties of your substances and how

they are put together.

(c) a drawing of your coating indicating its

special features and how it works.


Summary of key termsadhesion: the attraction between

particles of one substance to particles of another object or substance

bimetallic strip: a strip constructed from two different metals. Each of the metals must expand at a different rate. Bimetallic strips are often used in thermostats.

boiling: the change of state from a liquid to a gas. Boiling occurs when the entire liquid is heated and continues until the liquid turns completely into a gas.

bonds: the forces that hold particles (atoms) together

cohesion: the ability of particles to ‘stick’ together and pull each other along

compressed: squeezed into a smaller space. Gases can be compressed, but liquids and most solids cannot be compressed.

condensation: formation of liquid when a gas cools down. Condensation occurs on bathroom mirrors and on the outside of soft-drink bottles.

condensing: the change of state from a gas to a liquid

contract: become smaller in size

Battery

Invar

Copper

Siren

Bimetallic stripbends up whenheated.

diffuse: spread throughout another substance

diffusion: the spreading of one substance through another due to the movement of their particles

dissolved: describes a substance that has mixed completely with another so that it is no longer visible

evaporation: the change of state from a liquid to a gas. Evaporation occurs only from the surface of the liquid.

expand: increase in size due to the movement of particles in the substance

force: a push, pull or twistfreezing: the change of state from a

liquid to a solidfuel: substance that burns to produce

heatgas: state of matter with no fixed

shape or volumehydraulic: describes a machine that

uses liquids to exert a push (force) from one place to another. Hydraulic machines use liquids because they cannot be compressed.

liquid: state of matter that has a fixed volume, but no fixed shape

lubricants: substances with large particles that can slide easily over each other. Lubricants are used between surfaces that rub against each other. Lubricants reduce wear and increase the motion between the surfaces.

melting: the change of state from a solid to a liquid

meniscus: the curved upper surface of a liquid. The curve forms when particles in the liquid ‘stick’ to the sides of the container they are in.

mixture: substance made up of two or more elements, two or more compounds, or a combination of elements and compounds. The elements or compounds in a mixture are not bonded together.

particle model of matter: a model that explains the behaviour and properties of each of the states of matter

particles: the individual parts that make up all matter. (These particles are called atoms.)

pressure: the push of a substance against another. For example, a gas exerts pressure on the container it is in because the particles in the gas collide with (push on) the sides of the container.

rigid: stiff, not flexiblesiphon: a device that uses gravity to

move a liquid from one place to another

solid: state of matter that has a fixed shape and volume

state: the condition of a substance. The three main states of matter are solid, liquid and gas. A ‘state’ is also known as a ‘phase’.

sublimation: the change in state from a solid into a gas without first becoming a liquid (or from a gas into a solid without first becoming a liquid).

surface tension: the ‘firmness’ of the surface of a liquid created by the attraction between particles at the surface of the liquid

transferred: moved from one place to another

volume: the amount of space taken up by an object or substance

water vapour: water in its gas state. The temperature of the water is less than 100 °C when it forms water vapour.

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61 02898 SAVic1 Ch02catalogimages.johnwiley.com.au/.../SAVic1_Ch02.pdf · 2008-01-20 · 24 Science Alive 1 for VELS Change of state ater is the only type of matter that exists in