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Ch - 1 MATTER
IN OUR SURROUNDINGS
Class 9
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Syllabus – Matter - Nature
and Behaviors
Definition of - Matter, solid, liquid, and gas.
Characteristics shapes, volume, density. Change of state - melting (absorption of
heat), freezing, evaporation (cooling by evaporation) condensation,
sublimation.
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1. Matter - The matter is defined as one which occupies space,
has mass, and is realized by our sense.
Matters may be solid, liquid, or gas.
2. Latent heat - Latent heat is the hidden heat that is required to
convert the matter from one state to another state without a change in
temperature.
3. The latent heat of vaporization - The latent heat of vaporization is the quantity of heat in joules required
to convert 1 kg of liquid to vapour or gas without a change in
temperature.
4. The latent heat of fusion - The latent heat of fusion is
the quantity of heat in joules required to convert 1 kg of solid to liquid
without a change in temperature.
5. Sublimation - Sublimation is the
process by which solid on heating directly changes into the gaseous state
without a change in a liquid state and vice versa.
Example- Iodin, camphor, naphthalene, dry ice, etc.
change directly into a gaseous state when they are heated.
6. A sponge is solid while it is compressible like gas - A
sponge is solid and has many small holes, in which air is trapped. When we
press it, the air is expelled out and we are able to compress it.
7. The melting point of most of the substances increases with
an increase in pressure. However, the melting point of ice
decreases with an increase in pressure.
8. The necessity of heat energy to melt a solid - In a solid intermolecular force between the particles is very strong so
heat energy is essential to overcome the intermolecular force.
9. Fusion - Solid-state on heating changes into a liquid state.
This phenomenon is called fusion.
10. Diffusion - The rate of diffusion increases on heating because when the temperature of a substance is increased by heating, its particle gains kinetic
energy and move more rapidly.
11. Diffusion helps aquatic animals and plants to survive in water- Diffusion
is the property of gases that helps aquatic animals and plants to survive in
water. Respiratory gases oxygen and carbon dioxide
diffuse in water and helps them to breathe in the water.
12. Brownian motion. The rapid and zig-zag movement of tiny particles in a
liquid is called Brownian motion. This motion increases on heating because the
movement of tiny particles gain kinetic energy and move faster.
13. Two factors that determine the rate
of diffusion
(a) Temperature - Diffusion increases
with an increase in temperature.
(b) Density - Diffusion increases with a decrease in density.
14. The states of matter on the basis
of kinetic theory -
(i) When the intermolecular forces between the particles
are strong, particles come closer and occupy a solid-state.
(ii) When the intermolecular force between the
particles are weak, particles stay far apart from one another and occupy
either liquid or gaseous state.
15. Liquefying of gas - When the pressure is increased on gas, the gas undergoes condensation that
is it liquifies and changes into a liquid state.
16. Three states are interconvertible:
When the solid matter is heated, it changes into the liquid by absorbing
heat energy and this phenomenon are called melting.
17. The full form of LPG and CNG. -
Full form of LPG - Liquefied petroleum gas
Full form of CNG - Compressed natural gas.
18. Evaporation -When the liquid matter is heated, it changes into
the gaseous state by absorbing heat. This phenomenon is called
evaporation.
19. Condensation - Gaseous state on cooling changes into the liquid
state by releasing heat energy and this phenomenon are called condensation.
20. Atmospheric pressure - The pressure of air in the atmosphere is
called atmospheric pressure.
The atmospheric pressure at sea level is 760 mm of Hg or 76 cm of Hg.
1 atmosphere = 101325 Pa
21. The S.I units of
(i) Mass ----- Kg ( Kilogram)
(ii) Length ---- m
(iv) Temperature --- K ( Kelvin)
(v) Force -- N (Newton)
(vi) Volume --- m3( Cubic
meter)
(v) Density --- Kg/m3
(vi) Pressure -- Pa ( Pascal)
22. Dry ice - Solid carbon dioxide is called dry ice. It is used as
a cooling agent.
Carbon dioxide gas is first pressurized and cooled to form liquid CO2 and
once released to atmospheric pressure, the liquid carbon dioxide converts to
dry ice and CO2(g).
23. Frosting - Conversion of gas to solid directly without
changing into a liquid is called frosting.
24. The smell of hot sizzling food reaches you several
meters away, but to get the smell from cold food you have to go close. - The rate of evaporation, kinetic energy, and diffusion increases with
the rise in temperature. Thus the smell of hot sizzling food reaches us from
several meters away. The rate of evaporation, kinetic energy, and diffusion of
cold food, comparatively less than hot food. So cold food realized only on
coming closer.
25. A diver is able to cut through water in a swimming
pool - A diver is able to cut through water in a
swimming pool because of a weak intermolecular force of attraction between
water molecules. The diver used streamlines action to reduce this force.
26. The characteristics of the particles of matter
-
(i) Matter in either of the state (solid, liquid, or gas) is composed of very
small particles of molecules or atoms or ions.
(ii) The constituent particles, atoms, molecules, or ions
have space between them.
(iii) The particle of matter is held together by
intermolecular force.
(iv) Particles of matter are always in a state of motion.
(v) Particles of matter possess kinetic and potential
energy.
27. The increase in temperature affect the rate of
diffusion - Kinetic energy is possessed by particles of matter
in motion. When the temperature is increased, kinetic energy increases, and the
rate of movement of particles also increases. The higher the temperature,
the higher the kinetic energy, and the faster the rate of diffusion.
28. The kinetic theory of matter - The theory which visualizes that any substance whether solid liquid or gas
is made up of tiny particles atoms molecules or ions which are in constant
motion is called the Kinetic theory of Matter.
29. We wear cotton clothes in summer - Because cotton cloths are a good absorber of water so in summer it
absorbs sweat from our body and evaporates it in the atmosphere by absorbing the heat from our body and the heat of the body gets dissipated during evaporation
of sweat and keeps us cool.
30. Differences between gas and vapour:
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Vapour
i. A substance which under ordinary temperature is a
solid or liquid, but under specific conditions is gaseous, is called vapour.
ii. It is a substance above its boiling point temperature.
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Gas
i. Gas is a substance above its critical temperature but below its critical pressure.
ii.It a substance that exists in the
gaseous state under ordinary conditions.
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31. Differences between
evaporation and boiling.
(a) Evaporation occurs at any temperature,
but boiling occurs only at boiling points.
(b) Evaporation produces a cooling effect,
but boiling produces a heating effect.
(c) It is a surface phenomenon, but boiling
is a bulk phenomenon (whole part of the liquid).
32. What happens when the temperature of the solids increases - When the temperature of the solid is increased, the
supplied heat absorbed by the constituent particles and therefore the kinetic
energy of the constituent particles increases. Due to this and intermolecular the force of attraction decreases and inter-molecular space increases and
solid starts changing into a liquid state.
33. On increasing the wind speed, the rate of
evaporation increases - 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.
Hence evaporation increases.
34. Evaporation is a surface phenomenon
- The particles of the surface of liquids which
are in contact with surroundings, gain heat energy from surroundings and its
kinetic energy increases, due to these particles of the surface of the water
evaporate. So evaporation takes place at the surface of a liquid
and we say that evaporation is a surface phenomenon.
35. A wooden chair should be called a solid
and not a liquid - Because a wooden
chair that is solid, have least and fixed inter-particle space
between their molecules, constituent particles are closely packed and can
vibrate about a fixed axis.
While in liquids they have more
inter-particle space between their molecules than solid, constituent
particles are loosely packed and free to move in such a way that they remain in
contact with one another. So a wooden chair is called a solid.
36. Evaporation causes cooling - Evaporation requires heat energy. The particles of
surface liquid absorb this heat energy from its surroundings during evaporation
and thus temperature is lowered and one feels cool.
37. Our palm feels cold when we put some
acetone or petrol or petroleum on it - Due
to evaporation of low boiling point liquids that is acetone by absorbing the heat
from our palm.
38. The water kept in an earthen pot becomes
cool during summer - In summer the temperature
is more and evaporation becomes faster. The earthen pots are porous and allow
the tiny water particles to get evaporated. The heat required for evaporation
is supplied by water kept in the pot. So the water kept in an earthen pot
becomes cool during summer.
39. A desert cooler cools better on a hot dry
day - On a hot dry day, the temperature is
more and humidity is low due to which the rate of evaporation of water becomes
faster. Due to the increase in the rate of evaporation more water gets
vaporized and cooling is better.
40. The interconversion of three states of the matter with the
the help of a chart.
(i) Solid to Liquid: Fusion
(ii) Liquid to Gas: Vaporization
(iii) Gas to liquid: Condensation
(iv) Liquid to Solid: Solidification
(v) Solid to Gas: Sublimation
(vi) Gas to Solid: Frosting
41. The various factors affect the rate of evaporation - Factors
affect the rate of evaporation:
I. Temperature- Evaporation increases with an
increase in temperature.
ii. Humidity - Evaporation
increases with a decrease in humidity.
iii. Wind speed- Evaporation increases with an increase in wind speed.
iv. Surface area-Evaporation increases with
an increase in surface area.
42. Gases are more
compressible - Force of attraction between molecules
of gases is negligible due to which intermolecular space is maximum than solid
and liquid. That is why gases are more compressible.
43. Reason of water droplets forming on the outer surface of a glass
containing ice-cold water - The water vapour present in the atmosphere, on coming in contact with the cold glass of water and
condense into water droplets (in liquid state).
44. During the summer, we perspire more
- In summers temperature of the outside
is more than our body temperature so to get equilibrium our body temperature
starts increasing so as to cool our body sweat glands produce sweat so that it
can evaporate and take the heat of our body hence cooling.
45. The level of water does not change
when salt dissolves in water - When we dissolve salt in water, the level of water does
not change because the particles of water are
loosely packed and having space between them which is known as
intermolecular space. This intermolecular space accommodates the salt
particles.
46. Water boils below 100
degrees C at the mountain - Water
boils when its vapour pressure becomes equal to the atmospheric pressure which
is 76 cm of Hg. Atmospheric pressure at the mountain is less than 76 cm of
Hg. So water boils below 100 degrees C at the mountain.
47. The heat energy is more in steam than in water at 100 degrees C or 373 K
(100C + 273) - Particles in steam, that is, water vapour at 373
K (100 C) has more energy than water at the same temperature. This is because
particles in steam have absorbed extra energy in the form of latent heat of
vaporization.
48. The heat energy is more in the water at 0 degrees C or 273 as
compared to particles in ice at the same temperature - particles in
water at 0 C (273 K) have more energy as compared to particles in ice at the
same temperature because particles in water have absorbed extra energy in
the form of latent heat of fusion.
49. The differences in the
characteristics of states of matter.
Solid | Liquid | Gas |
1. The constituent particles are tightly packed. | The constituent particles are loosely packed. | There is no definite arrangement in particles. |
2. The interparticle distance is fixed and is very small. | Inter-molecular space is small but greater than solid. | Intermolecular space is very large compared to the solid and liquid. |
3. Solid - Have definite shape, sizes, and volume. | Have no definite shape, and size but have a definite volume, it acquires the shape of containers. | Have no definite shape, definite volume, and size, it acquires the shape of containers. |
4. Solids are very less compressible. | Liquids are less compressible but more than solid. | Gases are highly compressible due to the presence of a very large space between the molecules. |
50. A gas fills completely
the vessel in which it is kept - The
particles of gas are free to move in any direction due to very weak the inter-particle force which is negligible, That is why a gas fills completely
the vessel in which it is kept in
51. A gas exerts
pressure on the walls of the container - Since the particles of a gas are free to move in
all the possible direction, they strike the walls of the container with a
definite force per unit area and exert a definite force under a given set of
conditions to develop pressure.
52. A wooden table should be called a solid - In a wooden table, the constituent particles are unable
to exert translational motion because they are held together by strong cohesive
forces due to which wood has definite shape, volume, and size. Therefor a
wooden table is called a solid.
53. We can easily move our hand in the air but to do the same through a solid
block of wood we need a karate expert - The constituent particles of
wood which is solid held together by strong intermolecular force, the movement
of hand through a solid block of wood, therefore, require a large amount of
energy to separate the particles so only a karate expert is able to exert such
a large force and is able to do so.
54. While putting clothes
for drying up we spread them out - Spreading
the cloths for drying increases the surface area which helps it to dry faster
as the rate of evaporation increases with an increase in area.
55. Clothes dry up faster when spread near a heater - Clothes dry up faster when spread near a heater because
the heater increases the temperature which helps it to dry faster as the
rate of evaporation increases with an increase in temperature.
56. Clothes take a very long time to dry on a rainy day - Clothes take a very long time to dry on a rainy day
because the rate of evaporation decreases with an increase in humidity.
57. Reason after a hot the sunny day people sprinkle water on the roof or open ground - After a hot sunny day roof and the open ground become
hot. When people sprinkle water, it evaporates and leads to a decrease in
temperature because water takes heat from the floor and ground for
evaporation.
58. The smell of lighted
incense stick reaches you several meters away, but to get the smell from until
incense stick you have to go close - The
rate of evaporation, kinetic energy, and diffusion increases with the rise
in temperature. Thus the smell of lighted incense stick reaches us from several
meters away.
The rate of evaporation, kinetic energy, and
diffusion of until incense stick, comparatively less than lighted incense
stick. So until incense stick realized only on coming closer.
59. The naphthalene balls disappear with time without leaving any solid - Naphthalene balls are the sublime substances, so the
naphthalene balls disappear with time without leaving any solid, in which
substances are directly changed into the gaseous state without a change in
liquid.
60. The rate of diffusion
is faster in gas -
i. Force of attraction between molecules of
gases is negligible due to which particles can move freely.
ii. The kinetic energy of particles of gas is
more than solids and liquids.
That is why the rate of diffusion is faster
in gas.
61. Gases exert pressure on
the walls of containers - Force
of attraction between molecules of gases is negligible due to which particles
of gases can move randomly in all directions. During the motion, they collide
with each other and also with the walls of the container.
62. The rate of diffusion
of liquids is higher than that of solids - In the liquid state, the force of attraction
between the constituent particles is less than solid, particles move freely and
have greater space between each other as compared to particles in the
solid-state. So the rate of diffusion of liquids is higher than that of
solids.
63. Bose-Einstein Condensate - The BEC is formed by cooling a gas
of extremely low density, about one-hundred-thousandth the density of normal
air, to super-low temperatures. It was predicted by Albert Einstein in
2001, Eric A.
64. Plasma state of matter - The plasma is the fourth state of
matter consists of super energetic and super excited particles in the form of
ionized gases. In the fluorescent tube and neon sign bulbs neon gas and helium
gas or some other gases get ionized when electrical energy flows through it.
This ionized gas creates a plasma glowing inside the tube or bulb. The plasma
glows with a special colour and depends on the nature of the gas. The Sun and
the stars glow due to the presence of plasma in them. The plasma is
created in stars due to very high temperatures.
65. The interconversion of the state of matter is considered as a physical
change - The interconversion of the state of matter is considered as a
physical change as:
i. there is no change in the chemical properties of the matter.
ii. no new substance is formed, the substance remains the same in the different states.
iii. it is a reversible change, a substance
can back to its original state by physical means.
