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MATTER AND MATERIALS
UNIT I
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Properties of materials and the
kinetic theory
Properties of materials and the kinetic theory
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 MATERIALS are considered substance objects from which things are made
e.g. metals, ceramics, plastics, rubber, wood, glass, cement, leather, bone,
textiles, glues, paints, dyes, solvents, foodstuff, medicine etc.
Can
you add a few more?
Glass is a material which can be made into these objects
Properties of materials and the kinetic theory
---------------------------------------------------------------------------------------Material
 Common properties are:
 Colour, Texture, Hardness,
Flexibility, Strength, Density,
Specific Heat Capacity,
Conductivity (or The Converse
Electrical Resistance), boiling
point, melting point.
Object
tubing
Objects are made up of
materials which have:
 Shape
 Mass
 Volume,
Object
wire
Object
coin
Object
Jewellery /
ornament
Properties of materials and the kinetic theory
---------------------------------------------------------------------------------------Properties that describe the look or feel of a substance, such as colour,
hardness, density, texture, and phase, are called physical properties.
Every substance has its own set of characteristic physical properties that we
can use to identify that substance.
 For example, gold is an opaque, yellowish substance that is a solid at room
temperature and has a density of 19300 kgm-3.

Diamond is a
transparent
substance that is
a solid at room
temperature and
has a density of
3500 kgm-3.
 Water is a
transparent
substance that is
a liquid at room
temperature and
has a density of
1.0 kgm-3.

Properties of materials and the kinetic theory
---------------------------------------------------------------------------------------MATTER occupies space.
Matter generally exists as SOLIDS LIQUIDS OR GASES.
Temperature and Pressure determine the state of matter.
Energy is gained/lost when matter changes its state.

KINETIC (PARTICLE) THEORY OF MATTER
MATTER is made up of particles called atoms or molecules
 Particles are in constant random motion (rotation, vibration and / or
translate).
 Particles collide with each other if they move about.
 They collide with the particles in the walls of the container if they move
about.
 Energy is exchanged between particles during collision.

Properties of materials and the kinetic theory
---------------------------------------------------------------------------------------THE THREE STATES OF MATTER
The Kinetic theory of matter states that all matter is made up of particles,
and exists in one of three states, either solid, liquid or gas.
Their arrangements are often summarised as follows:

Solid
Liquid
Gas
In the solid state particles are in a fixed arrangement but can vibrate in 3
dimensions and rotate but cannot move about.
In the liquid state particles are free to move about and can vibrate in 3
dimensions and rotate.
In the gaseous state particles are free to move about and can vibrate in 3
dimensions and rotate.
Properties of materials and the kinetic theory
---------------------------------------------------------------------------------------Heat causes the bonds between the particles to weaken so when heated the
temperature rises then solids melt to liquids, whose temperature will rise until
they vaporize to gases.
The reverse happens when substances loose heat (cool). Loss of heat causes
the bonds between the particles to strengthen so when cooled the temperature
drops then gases condense to liquids, whose temperature will drop until they
freeze to solids.
Properties of materials and the kinetic theory
---------------------------------------------------------------------------------------KINETIC THEORY OF GASES
 Gas molecules move about with high speeds.
 Gas molecules are far apart.
 The forces between molecules are much less (negligible) than solids or
liquids.
 Increased temperature causes more vigorous motion in the molecules.
 Gases expand to fill their container.
 When molecules collide with the walls of the container this is called pressure.
There are two variables
affecting the volume of a
gas:
 Increased pressure
decreases volume.
 Increased temperature
increases volume.
Properties of materials and the kinetic theory
---------------------------------------------------------------------------------------EVIDENCE FOR KINETIC THEORY OF GASES
 Brownian motion.
 Evaporation.
 melting
 Freezing
 Boiling
 Diffusion
 Condensation
 Adhesion
 Cohesion
 Surface Tension
 Osmosis.
Brownian motion
Diffusion
Properties of materials and the kinetic theory
---------------------------------------------------------------------------------------GENERAL PROPERTIES – SOLIDS, LIQUIDS AND GASES
Properties
Solids
Liquids
Gases
Arrangement
of particles
Closely packed,
orderly
fashion
Randomly
distributed
clusters
Particles further
apart
Inter particle
strength
Very strong
Moderate
Very weak
Motion of
particles
Restricted motion Random motion
Vibration,
and freer to move
rotation.
around, vibration,
rotation. Confined
to the bulk of the
liquid
Move in clusters
Random motion
and freer to move
around, vibration,
rotation. Confined
only by container
walls.
Volume
Constant volume
Definite volume
Fill any space
Compressibility
Not easily
compressed
Pressure has
small effect
Easily compressed
Properties of materials and the kinetic theory
---------------------------------------------------------------------------------------EFFECT OF HEAT ON SOLIDS LIQUIDS AND GASES
States of
matter
Effects of Heat
Rate of diffusion
Solids
Expand slightly. eventually melts with
small increase in volume.
Temperature remains constant until all
the solid melts.
Very slow
Liquids
Expand slightly as temperature rises.
Boil eventually with large increase in
volume. Temperature remains steady
during boiling until all the liquid turns to
gas.
Slow
Gases
Expand considerably at constant
pressure. Pressure may increase if
confined in a closed container.
Rapidly
Properties of materials and the kinetic theory
---------------------------------------------------------------------------------------CHANGES IN STATE KINDS OF STATE CHANGES
EVAPORATION AND BOILING
 In evaporation a liquid changes to a gas at a temperature
below its boiling point.
 When a liquid is heated its particles move faster but at
different speeds continually colliding with each other and
with the walls of the container.
 Occasionally a particle acquire sufficient energy to escape
into the vapour.
 Once boiling has started the temperature remains steady.
The heat energy goes to
separate the particles from
one another by weakening
bonds.
 The escaping particles
take with them a lot of
energy – evaporation results
in cooling.
 Evaporation depends on nature of liquid, temperature
and surface area.
In boiling
vigorous
molecules form
bubbles inside
the water
EVAPORATION
High energy
molecules escape
Moderate energy
molecules are pulled
back into the liquid
Low energy
molecules remain in
the bulk
Properties of materials and the kinetic theory
---------------------------------------------------------------------------------------CHANGES IN STATE KINDS OF STATE CHANGES
 SUBLIMATION - In sublimation a solid changes
directly to a gas without going through the liquid
state.
 CONDENSATION takes place when a gas
changes to a liquid. A gas will condense when cooled
to or below its boiling point.
 BOILING takes place when a liquid is heated to
its boiling point.
FREEZING takes place when a liquid is cooled
below its freezing point
 MELTING takes place when a solid is heated
above its melting point.
Properties of materials and the kinetic theory
---------------------------------------------------------------------------------------HEAT AND STATE CHANGES
LATENT HEAT OF FUSION
If ice cubes below 0oC are heated, they warm up to 0oC.
 Then they begin to melt.
 Temperature stays at 0oC until all the ice melts
 The particles of the solid water (ice) absorb the heat energy which enables
them to overcome the forces which hold them in place in the solid state and
can now move about freely inside the bulk of the liquid.
LATENT HEAT OF VAPORIZATION
 If water below 100oC are heated, it warms up to 100oC.
 It begins to boil.
 Temperature stays at 100oC until all the water boils
 The particles of the liquid water absorb the heat energy which enables them
to overcome the forces which hold them in place in the liquid state and can now
move about freely unless confined in a container.
 All substances have latent heat of fusion and vaporization.
 These are absorbed at the melting point and boiling point of the substance.
 These are released at the freezing point and condensing point of the
substance.
Properties of materials and the kinetic theory
---------------------------------------------------------------------------------------HEAT AND STATE CHANGES
Water
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WATER COMMON PROPERTIES
 Colorless odorless and tasteless
 Remarkable solvent properties so it contaminate
easily
 Melting point or freezing point is 0oC
 Boiling point or condensing point is 100oC
 Density 1000kgm3
 Water is unique as it expands when it freezes
and so has a maximum density at 40C
PURIFICATION OF WATER
 Collection - in dams and reservoir.
 Sedimentation – aluminium sulphate is added to
help particles settle out.
 Filtration – to remove suspended matter
 Chlorination – to kill harmful bacteria.
 Reverse osmosis is used to remove dissolved
salts.
In some countries where oil is cheep distillation
may be used to remove dissolved salts
Solutions
--------------------------------------------------------------------------------------- SOLUTION – Homogeneous mixture
of two or more substances.
 SOLUTE – The substance that is
dissolved (usually the one that is the
smaller amount).
 SOLVENT – The substance that
does the dissolving (usually the one
that is greater amount).
 DISSOLVE – Breaking down of
solute particles in solvent until no
longer visible to the naked eyes.
Solutions can be:
 Solid in solid (e.g. Gold with copper for jewellery). Metals dissolved in
other metals are called alloys. Solid metal alloys e.g. brass, bronze, steel or
solder.
 Solid in liquid. e.g. Salt in water, nail polish pigments in acetone.
Gas in solid. e.g. Hydrogen in palladium.
 Liquid in liquid e.g. Alcoholic drinks.
 Gas in liquid e.g. Oxygen in water, Carbonated drinks.
 Gas in gas e.g. Air
Solutions
---------------------------------------------------------------------------------------PROPERTIES OF
SOLUTIONS
 Solute and solvent are
thoroughly mixed.
 Solute and solvent do
not separate normally.
 Solute particles are
not visible.
 Solution may be
colored but transparent.
 Solute may be
separated by physical
means.
Solutions
---------------------------------------------------------------------------------------DISSOLVING OF SOLUTE DEPENDS ON:
 PRESSURE – Significant for gases dissolved
in liquids
 TEMPERATURE – Most solids dissolve faster
at higher temperatures but gases tend to be
opposite.
 NATURE OF SOLUTE AND SOLVENT – Like
dissolves like.
 PARTICLE SIZE – Smaller particles dissolve
faster.
 STIRRING – Helps in dissolving.
SATURATED AND SUPERSATURATED
SOLUTIONS
SATURATED SOLUTION – Contains as much
solute as can possibly be dissolved at a given
temperature and pressure
SUPERSATURATED SOLUTION – Contains
more solute than can normally be dissolved in a
given amount of solvent at a given temperature
and pressure.
Suspensions and Colloids
---------------------------------------------------------------------------------------SUSPENSIONS AND COLLOIDS
 Distinguished by their particle size
 Suspensions – formed when solute particles
do not dissolve or partially dissolve. e.g. clay in
water, some medicines, germicidals.
 These settle out after the suspension is left
standing for some time.

Light passing
through a colloid
COLLOIDS AND EMULSIONS – solute
particle size break up so that they are mid
way between solution and suspension e.g
smoke, milk, aerosols,
Suspensions and Colloids
---------------------------------------------------------------------------------------SEPARATION OF MIXTURES
 Hand picking – particles must be large enough and have some property that
are different allowing them to be removed by inspection e.g. Picking rice.
 Decanting when one liquid floats on another e.g. Oil floating on water.
 Magnet – sand/sulphur and iron filings.
 Flotation – ping pong balls/golf balls using water.
 Sieves – these can be some kind of mesh which has holes where one
component is made up of smaller particles which can pass through the sieve
 Sieves can be used for separating gravel of different sizes
 Cloth or paper filters can be used for separating coffee grounds from
coffee.
 Filter paper can be used in the lab to separate undissolved materials
from a liquid.
 Evaporation to dryness – a liquid solvent can be removed from a solution by
boiling it away leaving the solid solute behind e.g. Sugar is made from cane
juice.
Suspensions and Colloids
---------------------------------------------------------------------------------------SEPARATION OF MIXTURES
 Simple or fractional distillation can be used to separate a liquid solvent can
be removed from a solution by boiling it away and condensing it. E.g. Simple
distillation for getting water from sea water. Fractional distillation for alcohol
is distilled from fermented products or separation of crude oil into various oils
and fuels.
 Dissolve one of the components of the mixture and evaporate to dryness e.g.
Sand and salt  dissolve salt in water and evaporate to dryness.
 Chromatography – pigments from flour petals.
Centrifugation – Spinning the suspensions, colloids very quickly.

Suspensions and Colloids
---------------------------------------------------------------------------------------HARD AND SOFT WATER
 Most sources of water, even water we drink, contains varying amounts and
types of impurities.
 Certain impurities make it difficult for soap to lather. This type of water is
called HARD WATER.
ACTION OF SOAP ON HARD WATER
Soap is made of Sodium(Na) + stearic acid
Calcium in hard water + stearic acid from soap = Calcium stearate (insoluble
white curdy precipitate).
HOW WATER BECOMES HARD
Rain water falling through the atmosphere mixes with and dissolves certain
acidic gases found in the atmosphere making the rain water acidic. e.g. water +
carbon dioxide  carbonic acid. In industrial areas nitric acid and sulphuric
acid are also formed.
 Acidic rain water falling on calcium or magnesium bearing rocks react with
these substances and the products dissolve in the water making what is known
as HARD WATER.
Suspensions and Colloids
---------------------------------------------------------------------------------------TYPES OF HARDNESS
 Calcium carbonate [CaCO3] and magnesium carbonate [MgCO3] are insoluble
rocks but acid rain (carbon dioxide) changes these to calcium calcium hydrogen
carbonate [Ca(HCO3)2] and magnesium hydrogen carbonate[Mg(HCO3)2] .
 Temporary hard water is caused by dissolved calcium and magnesium
hydrogen carbonate.
 Permanently hard water is caused by dissolved calcium sulphate [CaSO4] and
also magnesium sulphate [MgSO4] in water.
 These substances react with soap so that it does not lather.
 SOFTENING HARD WATER - temporary hard water
 Boiling
Ca(HCO3)2 → CaCO3 + CO2
 Adding calcium hydroxide
Permanently hard water
 Adding washing soda crystals –sodium carbonate
 Temporary and Permanent Hardness
 Commercial water softener
 Ion exchange resin
 Distillation
Determining mass and volume
---------------------------------------------------------------------------------------Mass is measured with a
balance.
Equal arm balances
 Spring balance
Determining mass and volume
---------------------------------------------------------------------------------------Liquid volume is measured with a measuring
cylinder.
 Read a measuring cylinder at eye level and the
bottom of the meniscus.