31656441 matter in our surroundings

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1 | P a g e R A J I V S H A R M A C L A S S E S 9 3 1 2 4 3 7 8 2 4

BY VIVEK MISHRA

MATTER IN OUR SURROUNDINGS

MATTER:-anything which occupies space and has mass is called Matter. Air and Water; hydrogen and oxygen;

classified in many ways. Modern day scientists have classified matter in two ways :

1. On the basis of its physical its physical properties matter can be classified into three ways:

i. S olids

ii. Liquids

iii. G as

2. On the basis of chemical properties matter can be classified into three parts:

i . E lement

ii . C ompound

iii . M ixture

MATTER IS MADE OF PARTIC LES

Every matter around us is made of tiny particles. The number of particle in a matter is very large. The

particles of matter are very large even we cannot see them with high power microscope. The particles

which make up matter are constantly moving.T he particles w hich make up matter are Atoms or M olecule .

C haracteristics of particles of matter

i. The particles of matter are very small.

ii. The particles of matter have spaces between them.

iii. The particles of matter are constantly moving.

iv. The particles of matter attract each other.

C L ASSIFICATION OF MATTER AS SOLIDS, LIQUIDS AND GASES

Matter exists in three physical states : SOLIDS, LIQUIDS AND GASES.

1. PROPERTISE OF SOLIDS

i . Solds have fixed shape and volume

ii . Solids cannot be compressed.

iii . Solids have high densities.

iv . Solids dont fill their container completely.

v . Solids dont flow.

vi . Solids are rigid.

2. PROPERTIS OF LIQUIDS

MATTER

SOLIDS LIQUIDS GASES



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i . liqui h ix lu ut th t h ix sh

ii . Liqui s t r ss u h

iii . Liqui s r less enser th n s li s

iv . Liqui s cannot f ill their cont ainer complet ely.

v . Liqui s flow easily. Therefore they are called Fluids

3. PR

OPERTISE

OF G A SES

i . Gases neither have f ixed volume nor have f ixed mass.

ii . Gases can be compressed complet ely and easily.

iii . Gases have very low densities.

iv . Gases f ill their cont ainer complet ely.

v . Gases flow easily, Therefore they are called fluids.

SOLIDS

In solids particles are closely packed. A solid has fixed shape because the particles of thesolid are closely packed and their positions are fixed due to the strong force of attraction

between them. A solid has fixed volume and can not be compressed because the spaces

between its particles is fixed. A solid can not fill the container completely and cannot flow

because its particles are closely packed.

A rubber band changes its shape but we still call it a solid because it changes its shape

by the action of force and when the force is removed the rubber band rega ins its

shape.

I f salt and sugar not appear to have fixed shape but we still count them in solids

because the shape of the individual crystals is considered to be solid because the shape

of individual crystals is fixed. A sponge can be compressed easily but still we count them in solids because they have

minute pores in it which are filled with air. When we press the sponge air is expelled

from its holes making it highly compressible.

A solid cannot be compressed by either applying the pressure or by changing the

temperature.

LIQUIDS

In the liquids the particles are close together but they are not as close as solids. Spaces

between particles in liquids are slightly more than in solids. There is weaker force of attraction between the particles of liquids than in solids. They don¶t have fixed shape because

the positions of its particles are not fixed due to comparatively less strong force of attraction

between them. a liquid has fixed volume because at the given temperature, the spaces

between its particles are fixed. a liquid can not be compressed much because they have less

space between the particles of them. A liquid generally flows easily because its particles are

able to slide over another due to slightly weaker interparticle forces of attraction.



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A liquid cannot be compressed by applying the pressure it can be compressed by changing

the temperature.

GASES

In gases the particles are much farther apart from one another as compared to solids and

liquids. The spaces between the particles of gases are very large. The force of attraction

between the particles of liquids is negligible. Particles of gas are free to move in any

direction. A gas has not fixed shape because the position of its particles is not fixed. A gas

can be compressed easily because its particles are far apart from each other, there are large

spaces between them. A gas can fill the container completely because due to the h igh kinetic

energy and negligible forces of attraction, the particles of gas move with high speed in all

direction. A gas can flow easily because its particles are free to move anywhere.

Gas can be compressed by applying the pressure.

PROBLEMS FOR PR ACT I C E

1. State characteristic properties of each solids, liquids and gases.

2. Give reasons for saying wood is a solid.

3. Why does a gas exert pressure?

4. Why are gases are highly compressible whereas solids and liquids cannot be

compressed?

5. Why does gases have neither affixed shape nor a fixed volume?

6. What is general name of :

i. Rigid form of matter?

ii.

Fluid form of matter7. Name two gases which are supplied in compressed form in homes and hospitals.

8. Write the full form of CNG and LPG.

9. Give two reasons to justify:

i. Water is a liquid at room temperature?

ii. An iron almirah is solid.

DIFFUSION The spreading out and mixing of a substance with another substance due to the motion of its

particles is called diffusion. Diffusion goes on until uniform mixing is formed.

Diffusion occurs an solids, liquids and in gases. Fastest in gases and slowest in solids and

moderate in liquids.

Phenomena of diffusion tells us that the particles are constantly moving.

DIFFUSION IN GASES

The diffusion in gases is fastest than solids and liquids.

EXAMPLES

The smell of food being cooked reaches us even from considerable distance because

when food is cooked the some of the substances release gases having the smell of food



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in them. The particles of gases move very quickly and mix up with the air by diffusion.

When the air containing these gases reaches our nose we get the smell of food being

cooked.

The fragnance of burning incense stick spreads all around due to the diffusion of its

smoke in air. The particle of gas produced by the gases of incense stick move rapidly in

all directions. They collide with the particles of air present in the room, mix with air and

reach every part of the room.

The smell of perfumes spread due to diffusion of perfumes vapor into the air. When the

bottle of perfume is opened, then the liquid perfume quickly changes into vapors. The

perfume vapors move very rapidly in all directions in air and mix with the air particles

and hence spread with air particles.

Lpg in our homes is detected due to the diffusion of a strong smelling substance(ethyl

mercaptan) present in the cooking gas, into air.

CHAN G E OF S TAT E OF M ATT ER

Matter can exist in three physical states ; solids, liquids and gaseous state. Two factors which

decide wheater a given substance would be solid, liquid or gas are; Temperature and

Pressure.

EFFE CT OF CHAN G E OF T EMPER AT URE

By increasing the temperature a solid can be converted into liquid state; and a liquid can be

converted into gaseous state, and by decreasing the temperature a gas can be converted into

liquid state; a liquid can be converted into solid state.

1. SOLID T O LIQUID CHAN G E : MELT IN G

The process in which a solid substance is converted into liquid on heating is called

Melting. The temperature at which a solid substance changes into liquid is called

melting point. For example the ice melts at the temperature of 0 0C to form liquid

hence 00C is the melting point of ice.

2. LIQUID T O GAS : BOILIN G OR V APOURIS AT ION

The process in which a liquid changes into a gas on heating, is called boiling or

vaporization. The temperature at which a liquid boils and changes into a gas at

atmospheric pressure is called boiling point of the liquid. For example the boiling

point of water is 1000C.

3. GAS T O LIQUID : C ONDENS AT ION

The process of changing a gas to a liquid by cooling is called condensation.

Condensation Is reverse of boiling. For example when steam changes into water by

cooling it is called condensation.

4. LIQUID T O SOLID CHAN G E : FRREEZIN G

The process of changing a liquid into a solid by cooling is called freezing.



5 | P a g e R A J I V S H A R M A C L A S S E S 9 3 1 2 4 3 7 8 2 4

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The changing up of sollid into vapours on heating and of vapour s into solid on

cooling is known as Sublimation. The cooman substances which h undergo

sublimation are ammonium chloride, iodine, camphor, naphthalene, and

anthracene.

LAT E T H EAT

The heat energy which has to be supplied to change the state of a substance. Latent hest

does not change the temperature of a substance. It only changes the state of a substance. It

is called latent heat because it becomes hidden in the substance undergoing the change of

state, and does not show its presence by raising temperature. So latent heat cannot be

detected by thermometer.

Why latent heat does not cause a rise in temperature of a substance?

The latent heat which we supply is used up in overcoming the force of attraction

between the particles of a substance during the change of state. Latent heat does notincrease the kinetic energy of the particles of the substance. And since there is no

change in kinetic energy of the particles the temperature of a substance does not rise

during the change in state.

LATENT HEAT IS OF TWO TYPES;

1. Latent heat of fusion

2. Latent heat of vaporization.

LAT E p

T H EAT Oq

F U S I Op

(S OL ID T O L I QU ID CH Ap

GE)

The latent heat of fusion(melting) in of a solid is the quantity of heat in joules required to

convert 1 kilogram of the solid to liquid without any change in temperature. The latent heatof fusion of ice is 3.34×105 joules per kilogram.

Why t he temperature of melting ice does not rise even t hough heat is being

supplied continuousl y ?

In this process heat energy is used up in changing the state of solid substance by

overcoming the force of attraction between its particles. So amount of particles in

water at 00 C have more energy as compared to particles in ice at the same

solid

liquidgas



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temperature. Ice at 00 C is more effective in cooling a substance than water at the

same temperature.

L AT EN T H E AT OF V APOURIS AT ION ( LIQUID T O GAS CHAN G E)

The latent heat of vaporization is the quantity of heat in joules required to convert 1

kilogram of liquid to vapor or gas without any change in temperature. The latent heat

of vaporization of water is 22.5�

105 joules per kilogram.

W hy t he t emperat ure of boili n�

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The heat energy supplied to a boiling liquid is used up in cha nging the state of

the liquid substance by overcoming the force of attraction between its particles.

W hy t he bur n s c au sed by st eam are muc h more severe t han t ho se

c au sed by boili n g w at er t hou gh bot h of t hem are at t he same

t emperat ure? This is due to the fact that steam contains more heat in the form of latent heat than

boiling water.

EFFE CT OF CHAN G E OF PRESSURE

The physical state of mater can also be changed by changing the pressure.

Gas can be changed into liquids by increasing the pressure accompanied by lowering the

temperature. And some solids like solid carbon dioxide can change into gases on decreasing

the pressure.

There is a lot of space in between the particles of gas. We can reduce the spaces between the

particles of a gas by enclosing it in a cylinder and compressing it by pushing in the piston. If

enough force is applied by the piston the gas is highly compressed. The particles of the gas

get so close together that they start attracting each other to form li quid. Ammonia gas can be

liquefied by applying the pressure and lowering temperature.

Solid c ar bon dioxid e i s stored und er high pressure?

This is because decreasing the pressure on solid co2 it gets converted directly into gas

CO2. Solid CO2 is extremely cold substance. It is used to deep freeze food and to keep

ice creams co2.

EV APOR AT ION

The process of changing up a liquid into vapor or gas even below its boiling point is calledEvaporation.

Whatever be the temperature at which evaporation takes place the latent heat of

vaporization must be supplied whenever a liquid changes into a vapor or gas.

CAUSE OF EV APOR AT ION



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Some particles in liquid always have more kinetic energy than others. So even when a liquidis below its boiling point, some of its particles have enough energy to break the force of

attraction between the particles and escape from the surface of the liquid in the form of vapor.

F ACT ORS AFFE CT IN G EV APOR AT ION 1. T

EMPER AT

URE The rate of evaporation increases on increasing the temperature of the liquid. an

increase of temperature: With the increase of temperature, more number of particlesget enough kinetic energy to go into the vapor state.

2. SURF AC E ARE A OF LIQUID

an increase of surface area: We know that evaporation is a surface phenomenon. If thesurface area is increased, the rate of evaporation increases. For example, while putting

clothes for drying up we spread them out.

3. � H UMIDI TY OF A IR

Humidity is the amount of water vapour present i n air. The air around us cannothold more than a definite amount of water vapour at a given temperature. If theamount of water in air is already high, the rate of evaporation decreases.

4. W IND SPEED

� an increase in wind speed: It is a common observation that clothes dry faster on awindy day. With the increase in wind speed, the particles of water vapour move away

with the wind, decreasing the amount of water vapour in the surrounding.

W hat i s t he c au se of cooli n g c au sed by evaporation?

When a liquid evaporates it draws the latent heat of vaporization from anything whichit touches. By losing heat the substance gets cooled.

1. If we put A little of spirit or patrol at the back of our hand and wave it around the

spirit evaporates rapidly and our hands feels very cold. This is due to the fact thatto \change from liquid to gas state spirit requires latent heat of vaporization whichspirit takes by our hand. Our hand looses heat and gets cooled.

2. During hot summer days water is usually kept in earthen pots to keep it cool. The

earthen pot has a large number of pores in its walls. Some of water continuouslyseeps out through these pores. This water evaporate and continuously and takes

the latent heat of vaporization from the surface of the pot and remaining water. In

this way remaining water looses heat and becomes cool.3. Respiration or sweating is our body¶s method of maintain constant temperature. On

a hot day or after doing some physical exercise. When our body temperature tends

to rise too much our sweat glands give out moisture on our skin. When the sweatevaporates it takes the latent heat of vaporization from our body. This keeps ourbody cool.

31656441 matter in our surroundings

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