LESSON 1 - MATTER IN OUR SURROUNDINGS

MATTER
DIFFUSION
COMPRESSIBILITY
VOLUME
FLUIDITY
RIGIDITY
DENSITY
TEMPERATURE
MELTING /FUSION
FREEZING/SOLIDIFICATION
MELTING POINT
FREEZING POINT
BOILING/VAPORIZATION
CONDENSATION/ LIQUEFACTION
BOILING POINT
LIQUEFACTION POINT
LATENT HEAT
LATENT HEAT OF FUSION
LATENT HEAT OF VAPORIZATION
SUBLIMATION
SUBLIME
EVAPORATION
 Characteristics of Matter
Anything that has mass and occupies space is called matter. Modern scientists
have classified matter in two ways:
i) On the basis of their appearance ( physical properties)- solid, liquid
and gas
ii) On the basis of their composition (chemical properties)- elements,
compounds and mixtures

Particulate nature of matter

Characteristics of particles of matter

1) Matter is made up of very small particles which can be seen only with
an electron microscope.
2) Particles of matter have space between them called intermolecular
space.
3) Particles of matter attract each other with a force called
intermolecular force of attraction. It decreases with an increase in
the intermolecular spaces.
4) Particles of matter are continuously moving i.e they have kinetic
energy. The kinetic energy of the particles increases with an increase
in temperature.
Diffusion
The intermixing of particles of two or more substances on their own is called
diffusion. The factors affecting the rate of diffusion are
1. Temperature: The rate of diffusion is directly proportional to the
temperature. As the temperature rises the kinetic energy of particle
increases so the rate of diffusion increases
2. Density: The rate of diffusion is inversely proportional to the density
of the substances. As the density increases the space between the
particles decreases, so the rate of diffusion decrease.
 Physical Classification of Matter
The three forms of matter-solid, liquid and gas are called the states of
matter. The states of matter differ in their physical properties which can
be understood on the particle level.

Physical properties explanation on the basis of particle properties

PARAMETER SOLID LIQUID GASEOUS

Volume Fixed volume due to Fixed volume because No definite volume
high inter-particle the inter particle
because the inter
force which keeps the force of attraction is particle- forces are very
particles close to strong enough to keep weak so the constituent
each other. the liquid in a bulk. particles are free to move
in all directions and occupy
the available space
Fluidity Cannot flow but can Can flow from higher Can flow easily in all
be heaped. As level to lower level as directions as particles
particles vibrate at particles vibrate and vibrate and move freely
fixed positions and do slide past each other with high speed in all
not move from one directions
place to another
Rigidity/ Very rigid and have Not rigid because Not rigid because
definite definite shape as the particles can slide past particles move freely in all
shape particles are each other due to directions with high speed
arranged in definite comparatively weak due negligible inter
pattern due to strong inter particle force particle force
inter-particle force
Compres Incompressible as Incompressible as Highly compressible due
sibility inter particle space is inter particle space to large inter particle
less and inter particle less and inter particle spaces and negligible inter
force very strong force is strong particle force of
attraction
Density Density is high as the Density is lesser than Least density because
particles are closely solids because the particles are well
packed with minimum Particles are loosely separated with large inter
inter particle space so packed with some inter particle spaces so the
number of particles m spaces so the number of particles per
per unit volume number of particles unit volume decreases
increases per unit volume
decreases
Diffusion Do not diffuse Diffuses easily Diffuses easily because
because the particles because the particles the particles possess
possess less kinetic possess more kinetic maximum kinetic energy
energy so they just energy so they can slip so they move randomly in
vibrate at their and slide past each all directions at high speed
position other
Examples Ice, glass, metals, Kerosene, petrol, oil, Oxygen, helium, carbon
wood. water. dioxide, chlorine.

Inter-conversion of States of Matter

Matter can change from one physical state to another on altering the
conditions of temperature and pressure
Conversion of State with Change in Temperature

Temperature Conversion scale

To convert Celsius temperature to Kelvin, we add 273 (K =0C +273)
To convert Kelvin temperature to Celsius, we subtract 273 (0C =K - 273)
A. Conversion of solid into liquid state
• When a solid is heated, its particles absorb heat energy and the
kinetic energy of the particles increases. With the increase in the
kinetic energy the particles start moving with a greater speed and
this in turn increases the inter particular spaces and weakens the
inter particular forces.
• When the kinetic energy of the particles becomes more than inter-
particular forces, the particles start interchanging their positions
and the solid changes into liquid state.
• During melting, the temperature remains constant. The heat
energy supplied does not increase the kinetic energy of the particles
but is used up to weaken inter particle forces of attraction and
increase inter- particle spaces. The heat energy used up during
conversion of 1kg of solid to liquid at atmospheric pressure is called
latent heat of fusion.

B. Conversion of liquid into gaseous state

• When a liquid is heated, its particles absorb heat energy and the
kinetic energy of the particles increases. With the increase in the
kinetic energy the particles start moving with a greater speed and
this in turn increases the inter particular spaces and weakens the
inter particular forces.
• When the kinetic energy of the particles becomes more than inter-
particle forces, the energetic particles rapidly leaves the liquid and
change into gaseous state.
• During boiling, the temperature remains constant. The heat
energy supplied does not increase the kinetic energy of the particles
but is used up to weaken inter- particle forces of attraction and
increase the inter particle spaces. The heat energy used up during
conversion of 1kg of liquid to gas at atmospheric pressure is called
latent heat of vaporization.
 Importance of melting point and boiling point:
1. Melting point/Boiling point is a constant and can be used for identifying the
purity of the substance
2. Melting point/Boiling point of a solid /liquid is a good indicator of the
strength of the intermolecular forces between the molecules of the
solid/liquid. i.e Greater the melting/boiling point , more will be the
magnitude of intermolecular forces.

NOTE:
1. The physical state of matter at room temperature can also be determined
by the m.p and b.p
• If the m.p and b.p is above room temperature (taken as 25°C) it is a
solid.
• If the m.p. and b.p is below room temperature it is a gas.
• If the m.p is below and b.p is above room temperature it is a liquid.

2. During the process of melting or boiling the temperature does not

change after the melting/boiling point has been reached until the
conversion of the state is complete even though we heat the container
continuously.
The heat energy supplied gets used up in changing the state by overcoming
the force of attraction between the particles. The heat energy supplied does
not increase the kinetic energy of the particles so temperature remains
constant but is used up to weaken the inter- particle forces of attraction and
increase the inter particle spaces.
During the process of melting or boiling, the heat energy which absorbed
by the substance and stored (hidden) in the particles without showing any
rise in temperature, is known as latent heat.

C. Direct interconversion of a solid into gaseous state

1. Solids like ammonium chloride, camphor, iodine, naphthalene, solid

carbon dioxide, on heating, directly change into the gaseous state
without first changing into the liquid state. Conversely the gaseous
state, on cooling, changes back into the solid state without changing
 into the liquid state. This process is
known as sublimation. Sublimation.
The gaseous form of matter directly
formed from a solid on heating is known
as sublime. The solid state of matter
formed directly from its gaseous state
on cooling is known as sublimate.

Gas and vapour mean the same thing yet,

they are different.
The term vapour is used to describe most gases
that usually exist as liquid at room
temperature. E.g.:- Water exists as a liquid at room temperature thus water
in its gaseous state is called water vapour.
Similarly alcohol, diesel, perfume, kerosene are liquids at room
temperature. Thus these gases are known as vapour.
The term gas is used to describe the gases that usually do not exist as
a liquid at room temperature. E.g.:-Oxygen does not exist as a liquid at room
temperature. Thus the gaseous state of oxygen is called gas. Similarly
hydrogen, nitrogen, chlorine and carbon dioxide gases are gases.

Conversion of State with Change in Pressure

States of matter can be altered with application of pressure.

At high pressure, the particles of a gas get compressed i.e the particles come
closer so the inter particle space decreases and the inter particle force of
attraction increases. On increasing the pressure continuously, the gas will
change into a liquid and further into a solid.
Thus applying pressure and reducing the temperature we can liquefy gases.
Conversely, if the pressure is reduced, the liquid can change to gaseous state

Solid carbon dioxide or dry ice

Carbon dioxide gas can be liquefied or solidified at low temperature and under
high pressure. Solid CO2 is called as dry ice as it resembles ice but does
not wet things. If the pressure on dry ice is reduced to 1 atmosphere, it
directly changes to vapour state without passing through the liquid state.
 EVAPORATION
The phenomenon of change of a liquid into vapour at any temperature below
its boiling point is called evaporation.
Explanation of evaporation on the basis of kinetic theory of particles:
In a liquid, particles move randomly and have different kinetic energy. These
particles are continuously acted upon by inter particle forces and pressure
due to air. Due to random motion, they hit against one another and kinetic
energy from one particle is transferred to the other. Thus some particles
become so energetic that they completely overcome the intermolecular forces
as well as pressure due to air. In such a situation, these particles leave the
liquid and escape into the air in the form of vapour.
Evaporation causes cooling.
During evaporation, energetic particles escape from the surface of the liquid
as vapours and the particles left behind are less energetic. This means these
molecules left behind have less average kinetic energy. As the temperature is
the function of average kinetic energy of the particles, the temperature of
the liquid decreases and the system cools down due to evaporation.
Factors affecting the rate of evaporation
Rate of evaporation increases with:-
1. Increase in surface area.
2. Increase in the temperature of the surroundings.
3. Increase in the motion of air.
4. Decrease in humidity.

Differences between boiling and evaporation

BOILING EVAPORATION
1. A process in which a substance 1. The process in which a substance
changes from the liquid state to changes from the liquid state to
the gaseous state at boiling the gaseous state below its
point boiling point.

2. Boiling is a bulk phenomenon as 2. Evaporation is a surface

occurs throughout the liquid phenomenon as takes place only
 from the exposed surface of the
3. Boiling takes place at a fixed liquid
temperature( boiling point)
3. Evaporation takes place at all
4. Fast process temperature
4. Slow process
5. Source of energy is needed
5. Energy supplied is by the
surroundings

REAL LIFE APPLICATION:

• A desert cooler cool better on a hot dry day.
In a desert cooler when the air is blown on a wet khas(grass), rapid
evaporation takes place, thereby cooling the air. The desert cooler cools
well on a hot day because the rate of evaporation increases on account
of decreased humidity and increased temperature.
• Water kept in an earthen pot become cool during summer.
Earthen pots are porous. When the water comes out of the pores of the
earthen pot during summer, it evaporates rapidly. As cooling is caused
by evaporation, therefore, the temperature of water within the pot falls
and hence it becomes cool during summer
• Our palm feels cold when we put some acetone, petrol or perfume on
it.
All these liquids are highly volatile and evaporate on exposure to air. As
evaporation causes cooling, our palm feels cold.
• We able to sip hot tea or milk faster from a saucer rather than a
cup
If tea is too hot to sip, we pour it in the saucer. In doing so, we increase
the surface area and the rate of evaporation. Increase rate of
evaporation causes faster cooling of the tea in a saucer
• We wear cotton clothes in summer.
During summer we perspire because of the mechanism of our body which
keeps us cool. During evaporation, the particles at the surface of the
liquid gains energy from the surroundings or the body surface and
change into vapour. The heat equal to the latent heat of vaporisation is
absorbed from the body leaving it cool. Cotton, being a good absorber of
 water helps in absorbing the sweat and exposing it to the atmosphere
for easy evaporation. Thus, we must wear cotton clothes in summer.
• Naphthalene balls disappear with time without leaving any solid.
Naphthalene undergoes sublimation converting directly to its gaseous
form. The naphthalene vapours diffuse into the surrounding air and are
lost to the environment. Hence, the naphthalene balls disappear with
time without leaving any solid.
• We get the smell of perfume sitting several metres away.
Perfume is a volatile liquid so the perfume particles diffuse quickly into
the air and are spread widely by the random motion of air molecules.
Hence, we get the smell of perfume several metres away.
• Ice at 273K more effective in cooling than water at the same
temperature?
Ice in the process of melting absorbs a lot of heat from the surroundings
as latent heat of fusion. As a result the temperature of the surroundings
is lowered and effective cooling is caused. While water already in the
liquid form, absorbs less heat from the surrounding.
• Steam produces more severe burns than boiling water.
Steam is formed when water at its boiling point of 1000C, absorbs a lot
of heat as latent heat of vaporisation. Therefore it has more energy
than boiling water. On account of this it produces more severe burns as
compared to boiling water.
• Water droplets are seen on the surface of a glass containing ice.
The vapour present in the air on touching the cold surface of the glass
loses energy and gets converted to the liquid state as droplets of
water.
GLOSSARY
• Matter: Anything that has mass, occupies space and
offers resistance to force applied on it
• Diffusion -The intermixing of particles of two or more
substances on their own is called diffusion.

• Substance: A material which is made up of same kinds of particles

• Compressibility: Reduction in the volume of the matter on application
of force
• Volume: The space occupied by a substance is called volume.
• Kinetic energy: The energy possessed by particles by virtue of its
motion.
• Fluidity: Tendency of the matter to flow.
• Rigidity: Property of a substance to resist change in its shape under
the action of small force.
• Density: Mass per unit volume of a substance
Mass
a. Density=
Volume
• Temperature: It is the measure of average kinetic energy of the
particles of matter.

• Melting /fusion: The process due to which a solid changes into a liquid
state at melting point by absorption of heat energy at atmospheric
pressure

• Freezing/solidification: The process of due to which a liquid changes

into a solid state at the freezing point by giving out heat energy at
atmospheric pressure

• Melting point: The temperature at which a solid changes to a liquid

state at the atmospheric pressure

• Freezing point: The temperature at which the liquid changes into the
solid state at atmospheric pressure.
a. Note: The numerical value of melting and freezing point is
same. E.g.: Melting point of ice is
0°Centigrade (C) or 273 Kelvin (K).
 i. Freezing point of water is 0°C or 273 K)

• Boiling/Vaporization: The process due to which a liquid changes into a

gaseous state at boiling point by absorbing heat energy at atmospheric
pressure

• Condensation/ liquefaction: The process due to which a gas changes

into a liquid state at condensation point by giving out heat energy at
atmospheric pressure

• Boiling point: The temperature at which a liquid changes into a gaseous

state at atmospheric pressure.

• Liquefaction point: The temperature at which a gas change into its

liquid state at atmospheric pressure.
a. Note: The numerical value of boiling point and condensation point
is same. e.g.: Boiling point of water is 100°C and 373 K
1. Condensation point of steam is also 100°C or 373 K

• Latent heat: The heat energy hidden in the molecules during the
change of state of matter.

• Latent heat of fusion: The amount of energy required to change 1kg

of solid at its melting point into liquid state, at atmospheric pressure

• Latent heat of vaporization: The amount of energy required to change

1kg of liquid at its boiling point into gaseous state, at atmospheric
pressure

• Sublimation: The process due to which a solid directly changes into

gaseous state on heating, without changing first into liquid state and
vice versa is known as sublimation.

• Sublime: A gaseous form of matter directly formed from a solid on

heating is known as sublime.

• Sublimate: The solid state of matter formed directly from its gaseous
state on cooling is known as sublimate.
 • Evaporation: The phenomenon of change of a liquid into vapour at any
temperature below its boiling point is called evaporation.

INTERNET REFERENCES /WEBSITES:

Video links:
SUBLIMATION
• https://www.youtube.com/watch?v=jX9pskbKSw0
CONVERSION OF STATE WITH CHANGE IN TEMPERATURE

• https://www.youtube.com/watch?v=ENVKQVIDNLY
• https://www.youtube.com/watch?v=jhTSRojj8K8

COMPARISON OF THE THREE STATES OF MATTER

• https://www.youtube.com/watch?v=bwGim-eceS8

PARTICULATE NATURE OF MATTER

• https://www.youtube.com/watch?v=nvbJSKhVWdU
• https://www.youtube.com/watch?v=MCrNjHcfcpY