Downloaded from Class 9... · x Solids and liquids cannot be compressed and they occupy definite volumes. x Gases can be easily compressed due to the large spaces between their particles

MATTER IN OUR SURROUNDINGS

SUCCESS CRITERIA

ACTIVITY

1.1

(10 marks)

SUCCESS CRITERIA

Date Diagram Observation Explanation

Conclusion

I have mentioned the

date on which the

experiment was

performed.

1 mark

I have drawn

a diagram.

My diagram is neat.

My diagram is well –

labeled.

3 marks


following keywords:

On addition of salt/ sugar the

water level does not change.

1 mark


following keywords:

Particles of water have

spaces between them.

Particles of salt occupy the

spaces between the

particles of water.

2 marks

I have mentioned the following

keywords:

Matter is made up of particles.

Particles of water have big


Particles of salt are small

enough to fit into the spaces

between the particles of water.

3 marks

ACTIVITY 1.2

(8 marks)

SUCCESS CRITERIA


Conclusion

I have mentioned

the date on which

the experiment

was performed.

1 mark

I have drawn

a diagram.

My diagram is neat.


labeled.

3 marks


following keywords:

With every dilution the colour

of potassium permanganate

in water becomes lighter.

1 mark


following keywords:

A few crystals of potassium

permanganate can colour a

large quantity of water.

There must be millions of

tiny particles of potassium

permanganate in just one

crystal of potassium

permanganate.

2 marks


keywords:

Matter is made up of extremely

small particles.

1 mark

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ACTIVITY 1.3

(16 marks)

SUCCESS CRITERIA


Conclusion

I have mentioned

the date on which

the experiment

was performed.

1 mark

I have drawn

a diagram.

My diagram is neat.


labeled.

3 marks


following keywords:

I could not smell the unlit

incense stick from a

distance.

I could smell the lighted

incense stick from a

distance.

2 marks


following keywords:

A burning incense stick

releases fragrant smoke.

This smoke consists of

particles which have high

kinetic energy.

The smoke particles with

high kinetic energy travel

through the big spaces

between the air particles.

This intermixing of particles

of smoke and air is

diffusion.

Unlit incense sticks do not

have high energy fragrant

smoke particles. Hence we

are not able to smell them.

5 marks


keywords:

Particles of matter move.

Therefore, particles of matter

possess kinetic energy.

Increase in temperature of

matter causes its particles to

move faster.

The kinetic energy of particles

increases with increase in

temperature.

The rate of diffusion becomes

higher with rise in temperature.

5 marks



ACTIVITY

1.4

(8 marks)

SUCCESS CRITERIA


Conclusion


date on which the

experiment was

performed.

1 mark

I have drawn

a diagram.

My diagram is neat.


labeled.

3 marks


following keywords:

The ink diffuses at a faster

rate than honey.

1 mark


keywords:

ink has very small solid particles

dissolved in water.

honey has large particles held

together by strong inter-

molecular forces of attraction.

2 marks


following keywords:

Larger particles diffuse

slowly while small particles

diffuse faster.

1 mark

ACTIVITY

1.5

(13 marks)

SUCCESS CRITERIA

Date Diagram Observation Explanation Conclusion

I have mentioned

the date on

which the

experiment was

performed.

1 mark

I have drawn

a diagram.

My diagram is

neat.

My diagram is

well – labeled.

3 marks


following keywords:

In water potassium

permanganate crystals

first settle down and then

slowly diffuse in the

water. A dense purple

solution

Potassium permanganate

diffuses faster in hot

water than in cold water.

2 marks

I have mentioned the following keywords:

Water molecules are continuously in

motion. The water molecules collide

against the potassium permanganate

crystals and break them down into

smaller particles.

The smaller potassium permanganate

particles are able to move faster.

Due to the random continuous motion of

water molecules and potassium

permanganate particles diffusion finally

takes place.

In hot water the molecules of water move

faster and have higher kinetic energy

than in cold water. The high energy water

molecules collide with the potassium

permanganate particles with more

energy. Hence diffusion is faster.

4 marks


following keywords:

Particles of matter are in

continuous motion.

Increase in temperature

increases the kinetic

energy of the particles.

Rate of diffusion becomes

higher on heating.

3 marks



ACTIVITY

1.7

(5 marks)

SUCCESS CRITERIA

Date Observation Explanation

Conclusion


date on which the

experiment was

performed.

1 mark

NO DIAGRAM

REQUIRED


following keywords:

It is easiest to break the

chalk and most difficult to

break the iron nail.

1 mark


keywords:

The particles in the iron nail

have the strongest forces of

attraction between them.

1 mark


keywords:

Particles of matter have forces of

attraction between them which

hold them together.

The strength of this force of

attraction between particles differs

from one matter to another.

2 marks

ACTIVITY

1.8

(7 marks)

SUCCESS CRITERIA

Date Observation Explanation

Conclusion


date on which the

experiment was

performed.

1 mark

NO DIAGRAM

REQUIRED


following keywords:

It is easy to break the

stream of water with one’s fingers.

The stream of water rejoins

once we remove our

fingers.

2 marks


following keywords:

The particles of water are

loosely packed hence ir is

easy to break the stream

of water.

The water stream rejoins

due to the forces of

attraction between the

particles of water.

2 marks


keywords:

Particles of matter attract each

other.

Particles of water have large


2 marks



ACTIVITY

1.11

(7 marks)

SUCCESS CRITERIA


Conclusion


date on which the

experiment was

performed.

1 mark

I have drawn

a diagram.

My diagram is neat.


labeled.

3 marks


following keywords:

It was easiest to push the

piston in the syringe which

had only air.

1 mark


following keywords:

There are large spaces

between the particles of

air.

1 mark


keywords:

Solids and liquids cannot be

compressed and they occupy

definite volumes.

Gases can be easily compressed

due to the large spaces between

their particles.

Gases do not have a definite

volume.

3 marks



MCQs – Particle Model of solids, Liquids and Gases

1. Which of the following best describes a SOLID?

fills container, takes shape of container, flows easily, low density

definite volume, definite shape, does not readily flow, high density

definite volume, takes shape of container, flows easily, high density

fills container, definite shape, does not readily flow, low density

2. The table shows the melting points and boiling points of some substances A to D. Which substance is a liquid at

-10oC and a gas at 10

oC?

Melting Point oC and Boiling Point

oC

-66 and 42

-142 and -78

-95 and 4

90 and 189

3. BOILING is the state change from?

liquid to gas

gas to liquid

liquid to solid

solid to liquid

4. Air is in a bottle with a tight screw-top. When the bottle becomes cooler, the pressure inside decreases

because the molecules of air?

move faster

move slower

become bigger

become smaller

5. The table below shows the melting points and boiling points of substances A to D. Which substance is suitable

to use in a thermometer that measures in the range -4oC to 50

oC?

Melting point oC (mpt), Boiling Point

oC (bpt)

mpt = 0, bpt = 100

mpt = -110, bpt = 80

mpt = 40, bpt = 350

mpt = -200, bpt = 40



6. The diagram shows an experiment using a light colourless gas (air) and a heavier brown coloured gas (bromine

or nitrogen dioxide). The gases fully mix together because?

all the gas particles can move around freely

of convection currents in the air

the gases have different densities (one is 'lighter' or 'heavier' than the other)

the air can sink into the coloured gas and the coloured gas can float on air

7. The diagram shows an experiment using a light colourless gas (air) and a heavier brown coloured gas (bromine

or nitrogen dioxide). The gases spread around in the gas jars by a process called?

evaporation

condensation

diffusion

sedimentation

8. Which of the following is the opposite of evaporating?

condensing

melting

freezing

boiling

9. Which of the following best EXPLAINS why liquids flow much more easily than solids?

liquid particles are lighter than solid particles

liquid particle attractive forces are weaker than solid particle attractive forces

liquid particles have more energy than solid particles

liquid particles can change shape more easily than solid particles

10. CONDENSING is the state change from?

liquid to solid

gas to liquid

liquid to gas

solid to liquid

11. Which describes sand?

a liquid

a gas

difficult to classify simply as gas, liquid or solid



a solid

12. Starting with the solid, the graph shows the results of

measuring the temperature of substance X as it was heated from a low to a high temperature. Which of the

following is TRUE?

X is melting between times t0 and t1

X is boiling between times t2 and t3

temperature TE1 is the melting point of X

X is completely liquid between times t1 and t2

13. Which of the following best describes what happens to the particles of water vapour when it condenses?

They lose energy and and are closer and less free to move around

They gain energy and increase their freedom to move without significant attractio

They lose energy and lose freedom to move about

They gain energy and gain freedom to move about

14. Which of the following best EXPLAINS why the liquid in a glass thermometer expands with rise in

temperature?

the liquid particles get bigger expanding the liquid

the glass contracts forcing the liquid further up the tube

the liquid particles gain more energy and collide more forcefully

the glass particles gain more energy and push the liquid particles up the tube

15. Which of these is a gas?

sand

water

rock

oxygen

16. Gases diffuse because they?

have a low density

easily move as convection currents



are made of rapidly moving particles

have low boiling points

17. Which describes carbon dioxide?

a gas

a liquid

difficult to classify simply as gas, liquid or solid

a solid

18. Water turning to a solid is called?

freezing

boiling

condensing

melting

19. The table shows the melting points and boiling points of some substances A to D. Which substance is a liquid at

20 oC?

Melting Point oC and Boiling Point

oC

-142 and -78

-95 and 4

-66 and 42

90 and 189

20. Which of the following best describes what happens to the particles of ice when it melts?

They lose energy and lose freedom to move about

They lose energy and escape into the atmosphere

They gain energy and gain freedom to move about

They gain energy and break up into atoms of hydrogen and oxy



THE THREE STATES OF MATTER

GAS-LIQUID-SOLID PARTICLE THEORY MODELS

1. Particle model of gases

A gas has no fixed shape or volume, but always spreads out to fill any container.

There are almost no forces of attraction between the particles so they are completely free of each

other.

The particles are widely spaced and scattered at random throughout the container so there is no order

in the system.

The particles move rapidly in all directions, frequently colliding with each other and the side of the

container.

With increase in temperature, the particles move faster as they gain kinetic energy.

Using the particle model to explain the properties of a Gas

Gases have a very low density (‘light’) because the particles are so spaced out in the container (density

= mass / volume).

o Density order: solid > liquid >>> gases

Gases flow freely because there are no effective forces of attraction between the gaseous particles -

molecules.

o Ease of flow order: gases > liquids >>> solids (no real flow in solid unless you powder it!)

o Because of this gases and liquids are described as fluids.

Gases have no surface, and no fixed shape or volume, and because of lack of particle attraction, they

always spread out and fill any container (so gas volume = container volume).

Gases are readily compressed because of the ‘empty’ space between the particles.

o Ease of compression order: gases >>> liquids > solids (almost impossible to compress a solid)

Gas pressure

o When a gas is confined in a container the particles will cause and exert a gas pressure which is

measured in atmospheres (atm) or Pascals (Pa = N/m2) - pressure is force/area on which force is

exerted.

The gas pressure is caused by the force created by millions of impacts of the tiny individual

gas particles on the sides of a container.

For example - if the number of gaseous particles in a container is doubled, the gas pressure

is doubled because doubling the number of molecules doubles the number of impacts on the

side of the container so the total impact force per unit area is also doubled.



This doubling of the particle impacts doubling the pressure is pictured in the two diagrams below.

2 x

particles

===>

P x 2

If the volume of a sealed container is kept constant and the gas inside is heated to a higher

temperature, the gas pressure increases.

o The reason for this is that as the particles are heated they gain kinetic energy and on average

move faster.

o Therefore they will collide with the sides of the container with a greater force of impact, so

increasing the pressure.

DIFFUSION in Gases:

The natural rapid and random movement of the particles in all directions means that gases readily

‘spread’ or diffuse.

Diffusion is faster in gases than liquids where there is more space for them to move (experiment

illustrated below) and diffusion is negligible in solids due to the close packing of the particles.

Diffusion is responsible for the spread of odours even without any air disturbance e.g. use of

perfume, opening a jar of coffee or the smell of petrol around a garage.

The rate of diffusion increases with increase in temperature as the particles gain kinetic energy

and move faster.

Other evidence for random particle movement including diffusion:

When smoke particles are viewed under a microscope they appear to 'dance around' when illuminated

with a light beam at 90o to the viewing direction. This is because the smoke particles show up by

reflected light and 'dance' due to the millions of random hits from the fast moving air molecules. This is

called 'Brownian motion' (see below in liquids). At any given instant of time, the hits will not be even,

so the smoke particle get a greater bashing in a random direction.



http://www.docbrown.info/page03/3_52states.htm

http://www.docbrown.info/page03/3_52states.htm#A coloured gas


http://www.docbrown.info/page03/3_52states.htm#movement in liquids

2. Particle model of Liquids

A liquid has a fixed volume at a given temperature but its shape is that of the container which holds

the liquid.

There are much greater forces of attraction between the particles in a liquid compared to gases, but not

quite as much as in solids.

Particles quite close together but still arranged at random throughout the container, there is a little close

range order as you can get clumps of particles clinging together temporarily.

Particles moving rapidly in all directions but more frequently collisions with each other than in gases

due to shorter distances between particles.

With increase in temperature, the particles move faster as they gain kinetic energy, so increased

collision rates, increased collision energy and increased rate of diffusion.

Using the particle model to explain the properties of a Liquid

Liquids have a much greater density than gases (‘heavier’) because the particles are much closer

together because of the attractive forces.

Most liquids are just a little less dense than when they are solid

o Water is a curious exception to this general rule, which is why ice floats on water.

Liquids usually flow freely despite the forces of attraction between the particles but liquids are not as

‘fluid’ as gases.

o Note 'sticky' or viscous liquids have much stronger attractive forces between the molecules

BUT not strong enough to form a solid.

Liquids have a surface, and a fixed volume (at a particular temperature) because of the increased particle

attraction, but the shape is not fixed and is merely that of the container itself.

o Liquids seem to have a very weak 'skin' surface effect which is caused by the bulk molecules

attracting the surface molecules disproportionately.

Liquids are not readily compressed because there is so little ‘empty’ space between the particles, so

increase in pressure has only a tiny effect on the volume of a solid, and you need a huge increase in pressure

to see any real contraction in the volume of a liquid.

Liquids will expand on heating but nothing like as much as gases because of the greater particle attraction

restricting the expansion (will contract on cooling).

o Note: When heated, the liquid particles gain kinetic energy and hit the sides of the container more

frequently, and more significantly, they hit with a greater force, so in a sealed container the pressure

produced can be considerable!



The natural rapid and random movement of the particles means that liquids ‘spread’ or diffuse.

Diffusion is much slower in liquids compared to gases because there is less space for the particles to move

in and more ‘blocking’ collisions happen.

o Just dropping lumps/granules/powder of a soluble solid (preferably coloured!) will resulting in a

dissolving followed by an observable diffusion effect.

o Again, the net flow of dissolved particles will be from a higher concentration to a lower

concentration until the concentration is uniform throughout the container.

Diffusion in liquids - evidence for random particle movement in liquids:

o If coloured crystals of e.g. the highly coloured salt crystals of potassium permanganate are dropped

into a beaker of water and covered at room temperature.

o Despite the lack of mixing due to shaking or convection currents from a heat source etc. the bright

purple colour of the dissolving salt slowly spreads throughout all of the liquid but it is much slower than

the gas experiment described above because of the much greater density of particles slowing the

spreading due to close proximity collisions.

o The same thing happens with dropping copper sulphate crystals (blue, so observable) or coffee granules

into water and just leaving the mixture to stand.




Particle model of Solids

A solid has a fixed volume and shape at a particular temperature unless physically subjected to

some force.

The greatest forces of attraction are between the particles in a solid and they pack together as tightly

as possible in a neat and ordered arrangement.

The particles are too strongly held together to allow movement from place to place but the particles

vibrate about their position in the structure.

With increase in temperature, the particles vibrate faster and more strongly as they gain kinetic

energy.

Using the particle model to explain the properties of a Solid

Solids have the greatest density (‘heaviest’) because the particles are closest together.

Solids cannot flow freely like gases or liquids because the particles are strongly held in fixed positions.

Solids have a fixed surface and volume (at a particular temperature) because of the strong particle

attraction.

Solids are extremely difficult to compress because there is no real ‘empty’ space between the particles,

so increase in pressure has virtually no effect on the volume of a solid.

Solids will expand a little on heating but nothing like as much as liquids because of the greater particle

attraction restricting the expansion and contraction occurs on cooling.

o The expansion is caused by the increased energy of particle vibration, forcing them further apart

causing an increase in volume and corresponding decrease in density.

Diffusion is almost impossible in solids because the particles are too closely packed and strongly held

together with no ‘empty space’ for particles to move through.



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Downloaded from Class 9... · x Solids and liquids cannot be compressed and they occupy definite volumes. x Gases can be easily compressed due to the large spaces between their particles