Download - 22047806 Chemistry Form 4 Chapter 9
-
8/3/2019 22047806 Chemistry Form 4 Chapter 9
1/21
9.1 SULPHURIC ACID
9.1.1 Properties of sulphuric acid
1. Sulphuric acid is a strong mineral acid.
2. Its molecular formula is H2SO4.
3. It is soluble in water.
4. Sulphuric acid is a non-volatile diprotic acid.
5. It is a highly corrosive, dense and oily liquid.
6. Concentrated sulphuric acid is a viscous colourless liquid.
Figure 9.2 Properties of sulphuric acid
Figure 9.1 A molecule of
sulphuric acid.
Properties of
sulphuric acid
Non-volatile
acid
Diprotic
acid
Soluble inwater
Highly
corrosive
Oily
liquidViscous
colourless
liquid
Dense
http://www.answers.com/topic/mineral-acidhttp://www.answers.com/topic/hydrogenhttp://www.answers.com/topic/sulfurhttp://www.answers.com/topic/oxygenhttp://www.answers.com/topic/water-annabelle-chvostek-albumhttp://www.answers.com/topic/water-annabelle-chvostek-albumhttp://www.answers.com/topic/water-annabelle-chvostek-albumhttp://www.answers.com/topic/mineral-acidhttp://www.answers.com/topic/hydrogenhttp://www.answers.com/topic/sulfurhttp://www.answers.com/topic/oxygenhttp://www.answers.com/topic/water-annabelle-chvostek-album -
8/3/2019 22047806 Chemistry Form 4 Chapter 9
2/21
9.1.2 The uses of sulphuric acid
(1) To manufacture fertilisers
There are many fertilizers that can be made of sulphuric acid. Some of them are:
a) Calcium dihydrogen phosphate (superphosphate)
b) Ammonium sulphate
c) Potassium sulphate
(2) To manufacture detergents
Sulphuric acid reacts with hydrocarbon to produce sulphonic acid. Sulphonic acid
is then neutralized with sodium hydroxide to produce detergents. Examples of
hydrocarbon
(3) To manufacture synthetic fibres
Synthetic fibres are polymers ( long chain molecules). Rayon is an example of a
synthetic fibre that is produced from the action of sulphuric acid on cellulose.
(4) To manufacture paint pigments
The white pigment in paint is usually barium sulphate, BaSO4. The neutralization
2
2 H2SO4
+ Ca3(PO
4)
2 Ca(H
2PO
4)
2+ 2CaSO
4
sulphuric acid + tricalcium phosphate calcium dihydrogen phosphate
H2SO4+2NH
3 (NH
4)
2SO
4
sulphuric acid + aqueous ammonia ammonium sulphate
H2SO4+2NH
3 (NH
4)
2SO
4
sulphuric acid + aqueous ammonia
ammonium sulphate
http://www.answers.com/topic/hydrogenhttp://www.answers.com/topic/sulfurhttp://www.answers.com/topic/oxygenhttp://www.answers.com/topic/hydrogenhttp://www.answers.com/topic/sulfurhttp://www.answers.com/topic/oxygenhttp://www.answers.com/topic/hydrogenhttp://www.answers.com/topic/sulfurhttp://www.answers.com/topic/oxygenhttp://www.answers.com/topic/oxygenhttp://www.answers.com/topic/sulfurhttp://www.answers.com/topic/hydrogenhttp://www.answers.com/topic/oxygenhttp://www.answers.com/topic/sulfurhttp://www.answers.com/topic/hydrogenhttp://www.answers.com/topic/oxygenhttp://www.answers.com/topic/sulfurhttp://www.answers.com/topic/hydrogen -
8/3/2019 22047806 Chemistry Form 4 Chapter 9
3/21
As an acid
2%
Fertilisers
32%
Other
chemicals
16%
Paint pigment
15%
Detergents
12%
As an
electrolyte
10%
Synthetic
fibres
9%
Metal cleaning
2%Dyes
2%
of sulphuric acid and barium hydroxide produces barium sulphate.
(5) As an electrolyte in lead-acid accumulators
(6) To remove metal oxides from metal surfaces before electroplating
(7) To manufacture pesticides
(8) The uses of sulphuric acid in school laboratories are:
a. As a strong acid
b. As a drying or dehydrating agent
c. As an oxidising agent
d. As a sulphonating agent
e. As a catalyst
Figure 9.4 Uses of sulphuric acid in industry
3
-
8/3/2019 22047806 Chemistry Form 4 Chapter 9
4/21
9.1.3 The industrial process in manufacture sulphuric acid
1. Sulphuric acid is manufactured by the Contact process.
2. Sulphuric acid is produced from sulfur, oxygen and watervia the contact
process.
3. The Contact process involves three stages.
4. Stage I: Production of sulphur dioxide gas, SO2.
This can be done by two methods,
a) Bur ning of sulphur in dry air in the furnace.
b) Burning of metal sulphide such as zinc sulphide in dry air.
5. Stage II: Conversion of sulphur dioxide to sulphur trioxide , SO3.
This is then oxidised to sulfur trioxide under the following conditions:
a) The presence of a vanadium(V) oxide , V2O5 , as a catalyst.
b) A temperature of between 450C to 550C.
c) A pressure of one atmosphere.
4
Sulphur Sulphur dioxide Sulphur trioxide Sulphuricacid
I II III
S+ O2
SO2
2ZnS + 3O2 2SO2 +
2ZnO
2 SO2
+ O2
2 SO3
http://www.answers.com/topic/contact-processhttp://www.answers.com/topic/sulfurhttp://www.answers.com/topic/oxygenhttp://www.answers.com/topic/water-annabelle-chvostek-albumhttp://www.answers.com/topic/contact-processhttp://www.answers.com/topic/contact-processhttp://www.answers.com/topic/contact-processhttp://www.answers.com/topic/oxygenhttp://www.answers.com/topic/sulfur-trioxidehttp://www.answers.com/topic/vanadium-pentoxidehttp://www.answers.com/topic/sulfurhttp://www.answers.com/topic/oxygenhttp://www.answers.com/topic/sulfur-dioxidehttp://www.answers.com/topic/oxygenhttp://www.answers.com/topic/sulfur-dioxidehttp://www.answers.com/topic/sulfur-trioxidehttp://www.answers.com/topic/sulfur-trioxidehttp://www.answers.com/topic/sulfur-dioxidehttp://www.answers.com/topic/oxygenhttp://www.answers.com/topic/sulfur-dioxidehttp://www.answers.com/topic/oxygenhttp://www.answers.com/topic/sulfurhttp://www.answers.com/topic/contact-processhttp://www.answers.com/topic/sulfurhttp://www.answers.com/topic/oxygenhttp://www.answers.com/topic/water-annabelle-chvostek-albumhttp://www.answers.com/topic/contact-processhttp://www.answers.com/topic/contact-processhttp://www.answers.com/topic/contact-processhttp://www.answers.com/topic/sulfur-trioxidehttp://www.answers.com/topic/vanadium-pentoxide -
8/3/2019 22047806 Chemistry Form 4 Chapter 9
5/21
6. Stage III: Production of sulphuric acid
a) Sulphur trioxide is dissolved in concentrated sulphuric acid, H2SO4 to
produce oleum , H2S2O7
b) Oleum is reacted with water to form concentrated H2SO4.
7. In stage II,sulphur dioxide is dried first before being added to dry air to
produce sulphur trioxide. This is:
(a) To remove water vapour
(b) To remove contaminants
8. In stage III, sulphur trioxide is not dissolved directly in water to produce
sulphuric acid. This is because:
(a) sulphur trioxide has low solubility in water
(b) sulphur trioxide reacts violently and mists are formed instead of a liquid
5
H2SO
4+ SO
3
H2S
2O
7+ H
2O 2
H2SO
4
http://www.answers.com/topic/sulfur-trioxidehttp://www.answers.com/topic/oleumhttp://www.answers.com/topic/sulfur-trioxidehttp://www.answers.com/topic/sulfur-trioxidehttp://www.answers.com/topic/sulfur-trioxidehttp://www.answers.com/topic/sulfur-trioxidehttp://www.answers.com/topic/sulfur-trioxidehttp://www.answers.com/topic/oleumhttp://www.answers.com/topic/sulfur-trioxidehttp://www.answers.com/topic/sulfur-trioxidehttp://www.answers.com/topic/sulfur-trioxidehttp://www.answers.com/topic/sulfur-trioxide -
8/3/2019 22047806 Chemistry Form 4 Chapter 9
6/21
burned in air
a) the presence of a vanadium(V) oxide as a catalyst.
b) a temperature of between 450C to 550C.
c) a pressure of one atmosphere
dissolved in sulphuric acid, H2SO4
diluted with equal volume of water H2O
Figure 9.5 Flowchart ofContact process
6
Sulphur or metal sulphide
Sulphur dioxide, SO2
Sulphur trioxide, SO3
Oleum, H2S
2O
7
Concentrated sulphuric acid H2SO4
http://www.answers.com/topic/vanadium-pentoxidehttp://www.answers.com/topic/contact-processhttp://www.answers.com/topic/sulfur-dioxidehttp://www.answers.com/topic/sulfur-trioxidehttp://www.answers.com/topic/oleumhttp://www.answers.com/topic/oleumhttp://www.answers.com/topic/sulfur-trioxidehttp://www.answers.com/topic/sulfur-dioxidehttp://www.answers.com/topic/vanadium-pentoxidehttp://www.answers.com/topic/contact-process -
8/3/2019 22047806 Chemistry Form 4 Chapter 9
7/21
9.1.4 Environmental pollution by sulphuric acid
1. Sulphur dioxide is the main by- product produced when sulfur-containing
fuels such as coal or oil are burned.
2. Sulphuric acid is formed by atmospheric oxidation ofsulphur dioxide in the
presence ofwater. It also produces sulphurous acid.
3. Sulphuric acid and sulphurous acid are constituents ofacid rain.
4. Acid rain can cause many effects such as:
i. Corrodes concrete buildings and metal structureii. Destroys trees and plants
iii. Decrease the pH of the soil and make it become acidic
iv. Acid rain flows into the rivers and increases the acidity of water and kill
aquatic living things.
5. Hence, we must reduce the sulphur dioxide from the atmosphere by:
i. Use low sulphur fuels to reduce the emission of sulphur dioxide in exhaust
gases
ii. Remove sulphur dioxide from waste air by treating it with calcium
carbonated before it is released.
7
http://www.answers.com/topic/redoxhttp://www.answers.com/topic/sulfur-dioxidehttp://www.answers.com/topic/water-moleculehttp://www.answers.com/topic/sulfurous-acidhttp://www.answers.com/topic/sulfurous-acidhttp://www.answers.com/topic/acid-rainhttp://www.answers.com/topic/redoxhttp://www.answers.com/topic/sulfur-dioxidehttp://www.answers.com/topic/water-moleculehttp://www.answers.com/topic/sulfurous-acidhttp://www.answers.com/topic/sulfurous-acidhttp://www.answers.com/topic/acid-rain -
8/3/2019 22047806 Chemistry Form 4 Chapter 9
8/21
9.2 AMMONIA AND ITS SALT
9.2.1 Properties of ammonia
1. A colorless, pungent gas.
2. Its molecular formula is NH3
3. It is extremely soluble in water.
4. It is a weak alkali.
5. It is about one half as dense as air
6. It reacts with hydrogen chloride gas to producewhite fumes of ammonium chloride.
7. Ammonia is alkaline in property and reacts with dilute acids in
neutralization to produce salts. For examples:
8.Aqueous solutions of ammonia produces OH ions (except Na+ ion, K+ ion,
and Ca 2+ ion) forming metal hydroxides precipitate.
8
NH3
+ HCl NH4Cl
2NH3
+ H2SO4
(NH4)
2SO
4
NH3
+ HNO3
NH4NO
3
Fe3+ + 3OH Fe(OH)
3
Brownprecipitate
Mg2+ + 2OH Mg(OH)
2
Whiteprecipitate
Figure 9.6 A molecule of
ammonia.
http://www.answers.com/topic/salthttp://www.answers.com/topic/oxygenhttp://www.answers.com/topic/hydrogenhttp://www.answers.com/topic/oxygenhttp://www.answers.com/topic/hydrochloric-acidhttp://www.answers.com/topic/ammonium-chloridehttp://www.answers.com/topic/hydrogenhttp://www.answers.com/topic/sulfurhttp://www.answers.com/topic/oxygenhttp://www.answers.com/topic/hydrogenhttp://www.answers.com/topic/oxygenhttp://www.answers.com/topic/oxygenhttp://www.answers.com/topic/oxygenhttp://www.answers.com/topic/hydrogenhttp://www.answers.com/topic/oxygenhttp://www.answers.com/topic/oxygenhttp://www.answers.com/topic/hydrogenhttp://www.answers.com/topic/oxygenhttp://www.answers.com/topic/oxygenhttp://www.answers.com/topic/hydrogenhttp://www.answers.com/topic/oxygenhttp://www.answers.com/topic/oxygenhttp://www.answers.com/topic/hydrogenhttp://www.answers.com/topic/oxygenhttp://www.answers.com/topic/oxygenhttp://www.answers.com/topic/oxygenhttp://www.answers.com/topic/hydrogenhttp://www.answers.com/topic/oxygenhttp://www.answers.com/topic/sulfurhttp://www.answers.com/topic/hydrogenhttp://www.answers.com/topic/ammonium-chloridehttp://www.answers.com/topic/hydrochloric-acidhttp://www.answers.com/topic/salt -
8/3/2019 22047806 Chemistry Form 4 Chapter 9
9/21
Properties of ammonia
ColorlessPungent
smell
Extremely
soluble in
water
Weak
alkali
9. Some metal hydroxides such as zinc hydroxide and copper (II) hydroxide
dissolves in excess aqueous ammonia to form complexes.
Figure 9.7 Properties of ammonia
9.2.2 The uses of ammonia
9
Zn(OH)2
+ 4NH3 [Zn(NH
3)
4]2+ +
2OH
Cu(OH)2 + 4NH3 [Cu(NH3)4]2+
+ 2OH
http://www.answers.com/topic/oxygenhttp://www.answers.com/topic/hydrogenhttp://www.answers.com/topic/oxygenhttp://www.answers.com/topic/hydrogenhttp://www.answers.com/topic/hydrogenhttp://www.answers.com/topic/oxygenhttp://www.answers.com/topic/hydrogenhttp://www.answers.com/topic/oxygen -
8/3/2019 22047806 Chemistry Form 4 Chapter 9
10/21
1. The major use of ammonia and its compounds is as fertilizers.
2. Ammonia is also used for the synthesis of nitric acid.
3. Ammonium fertilizers contain ammonium ions, NH4+, that can be
converted into nitrate ions by bacteria living in the soil.
4. Nitrogen is absorbed by plants to produce protein in the form of nitrates,
NO3, which are soluble in water.
5. The effectiveness of ammonium fertilizers is determined by the percentage
of nitrogen by mass in them. The fertilizer with a higher percentage of nitrogen is
more effective.
6. The percentage of nitrogen by mass can be calculated using this formula:
9.2.3 The industrial process in manufacture of ammonia
1. Haber process is the industrial method of producing ammonia.
2. It needs direct combination of nitrogen and hydrogen under high pressure in the
presence of a catalyst, often iron.
3. Nitrogen gas used in Haber process is obtained from the frictional distillation of
liquid air.
4. Hydrogen gas used in Haber process can be obtained by two methods:
a) The reaction between steam and heated coke (carbon)
b) The reaction between steam and natural gas ( consisting mainly of
methane)
5. In the Haber process:
10
C + H
2O CO +
H2
CH
4+ 2H
2O CO
2+
4H2
Mass
of nitrogen
X 100%
Molar mass offertilizers
http://www.answers.com/topic/fertilizerhttp://www.answers.com/topic/fertilizerhttp://www.answers.com/topic/fertilizerhttp://www.answers.com/topic/fertilizerhttp://www.answers.com/topic/fertilizerhttp://www.answers.com/topic/fertilizer -
8/3/2019 22047806 Chemistry Form 4 Chapter 9
11/21
a) A mixture consisting of one volume of nitrogen gas and three volume of
hydrogen gas is compressed to a pressure between 200 500 atmospheres.
b) The gas mixture is passed through a catalyst of powdered iron at a
temperature of 450 - 550C.
c) At this optimum temperature and pressure, ammonia gas is produced.
9.3 ALLOYS
11
N2+ 3H
2 2NH
3
-
8/3/2019 22047806 Chemistry Form 4 Chapter 9
12/21
9.3.1 Physical properties of pure metals
1. Pure metals have the following physical properties :
a)Good conductor of electricity
b)Malleable
c) Ductile
d)High melting and boiling point
e)High density
2. Pure metals are weak and soft because the arrangement of atoms in pyre
metals make them ductile and malleable.
a) A pure metal contains atoms of the same size arranged in a
regular and organized closed-packed structure.
b) Pure metals are soft because the orderly arrangement of atomsenables the layers of atoms to slide over each other easily when an
external force is applied on them. This makes the matels ductile and
metals can be drawn to form long wires.
c) There are imperfections in the natural arrangements of metal
atoms. Empty space exist in the structures of pure metals. When
hammered or pressed, groups of metal atoms may slide into new
positions in the empty spaces. This makes metals malleable, able to be
made into different shapes or pressed into thin sheets.
3. The strong forces of attraction between metal atoms requires high energy
to overcome it. Hence, most metals have high melting points.
4. The close-packed arrangement of metal atoms results in the high density
of metals.
12
-
8/3/2019 22047806 Chemistry Form 4 Chapter 9
13/21
Properties of
metals
Good conductor of electricity
Ductile
High melting and boiling point
Malleable
High density
Figure 9.8 Properties of metals
9.3.2 Meaning and purpose of making alloys
1. An alloy is a mixture of two or more elements with a certain composition
in which the major component is a metal.
2. in the process of alloying, one or more foreign elements are added to a
molten metal. When the alloy hardens, the positions of some of the metal
atoms are replaced by the atoms of foreign elements, which size may be
bigger or smaller than the original metal atoms.
3. In an alloy, these atoms of foreign elements disrupt the orderly
arrangement of the metal atoms and also fill up any empty space in the
metal crystal structure.
13
http://www.answers.com/topic/chemical-elementhttp://www.answers.com/topic/chemical-element -
8/3/2019 22047806 Chemistry Form 4 Chapter 9
14/21
4. Hence, the layers of metal atoms are prevented from sliding over each
other easily. This makes the alloy harder and stronger, less ductile and less
malleable than its pure metals.
5. The properties of a pure metal are thus improved by making them into
alloys. There are three aims of alloying a pure metal:
a) To increase the hardness and strength of a metal
b) To prevent corrosion or rusting
c) To improve the appearance of the metal surface
9.4 SYNTHETIC POLYMERS
9.4.1 The meaning of polymers
1. Polymers can be defined as large molecules composed of numerous
smaller, repeating units known as monomers which are joined by covalent
bonds.
2. Polymerisation is the chemical process by which the monomers are joined
together to form the big molecule known as the polymers.
3. There are two types of polymerization process:
a) Addition polymerization
b) Condensation polymerization
4. A polymer is a very big molecule (macromolecule). Hence, the relative
molecular mass of a polymer is large.
5. The properties of polymer are different from its monomers.
6. Polymers can be divided into two types:
a) Naturally occurring polymers
i. This type of polymer exists in living things in nature like the plants
and animals.
14
-
8/3/2019 22047806 Chemistry Form 4 Chapter 9
15/21
ii. Examples of naturally occuring polymers are:
a) Protein
b) Carbohydrate
c) Natural rubber
iii. Naturally occuring polymers are formed by the joining of
monomers by polymerization.
Protein is formed by the joining of monomers known as amino acid.
Carbohydrate is formed by the joining of monomers known as glucose.
Natural rubber is formed by the joining of monomers known as isoprene.
b) Synthetic polymers
1. This type of polymer are man-made by chemical process in
the laboratories.
The raw material for synthetic polymers are obtained frompetroleum.
The types of synthetic polymers include:
a) Plastics
b) Fibres
c) Elastomers
4. Examples of plastics are
polythene(polyethylene),polyvinylchloride(PVC), polypropene
(polypropylene), polystyrene , Perspex and bakelite.
5. Polythene and PVC are produced by addition
polymerization
6. Examples of synthetics fibres are nylon and terylene. They
are produced by condensation polymerization.
9.4.2 Advantages of synthetic polymers
Strong and light
Cheap
Able to resist corrosion
15
-
8/3/2019 22047806 Chemistry Form 4 Chapter 9
16/21
Inert to chemical reactions
Easily moulded or shaped and be coloured
Can be made to have special properties
9.4.3 Environmental pollution caused by synthetic polymers
a) As most of polymers are non-biodegradable, they will not
decay like other organic garbage.
b) Burning of polymers release harmful and poisonous gases.
9.4.4 Methods to overcome the environmental pollution caused by synthetic
polymers
a) Reduce, reuse and recycle synthetic polymers
b) Develop biodegradable polymers
9.5 GLASS AND CERAMICS
1. The main component of both glass and ceramic is silica or silicon dioxide, SiO2.
2. Both glass and ceramic have the same properties as follow
a) Hard and brittle
b) Inert to chemical reactions
c) Insulators or poor conductors of heat and electricity
d) Withstand compression but not stretching
e) Can be easily cleaned
f) Low cost of production
3. Differences between glass and cerement are, glass is transparent, while
ceramic is opaque. Ceramic can withstand a higher temperature than normal glass.
4. Types of glass are
a) Fused glass
It is consist mainly of silica or silicon dioxide
It has high heat resistance
b) Soda lime glass
It cannot withstand high temperatures
c) Borosilicate glass
16
-
8/3/2019 22047806 Chemistry Form 4 Chapter 9
17/21
It can withstand high temperature
d) Lead glass
High refractive index
5. Uses of improved glass for specific purpose
a) Photochromic glass
It is sensitive to light intensity
b) Conducting glass
It conducts electricity
6. Ceramic is a manufactured substances made from clay, with the
main constituent of aluminosilicate with small quantity of sand and feldspar.
7. Superconductor is one improved ceramics for specific purposes.
Glass
1. Glass is made up from sand.
2. The major component of glass is SiO2.
3. There are four types of glass which are as follows:
Fused glass
Soda-lime glass
Borosilicate glass
Lead crystal glass
Name of glass PropertiesChemical
compositionExamples of uses
Fused glassVery high softening
point (1700 C)
hence, highly heat
resistant
Transparent to
ultraviolet and
infrared light
SiO2 (99%)
Ba2 O 3 (1%)
Telescope mirrors,
Lenses
Optical fibres
Laboratory glass
wares
17
-
8/3/2019 22047806 Chemistry Form 4 Chapter 9
18/21
Difficult to be made
into different shapes
Does not crack when
temperature changes
(very low thermal
expansion coefficient)
Very resistant to
chemical reactions
Soda lime glass
Low softening point
(700 C), hence, does
not withstand heating
Breaks easily
Cracks easily with
sudden temperature
changes (high
coefficient of
expansion)
Less resistant to
chemical reactions
Easy to be made into
different shapes
SiO2 (70%)
Na2O (15%)
CaO (3%)
Others (5%)
Bottles
Windowpanes
Light bulbs
Mirrors
Bowls
( The most widely
used type of glass)
Borosilicate
glassHigh softening point
(800C). Thus it is
heat resistant
Does not crack easily
with sudden
temperature changes
Transparent to
SiO2 (80%)
Ba2 O 3 (15%)
Na2O (3%)
Al 2 O 3
Laboratory apparatus
Cooking utensils
Electrical tubes
Glass pipelines
18
-
8/3/2019 22047806 Chemistry Form 4 Chapter 9
19/21
ultraviolet light
More resistant to
chemical reactions
Does not break easily
Lead crystal
glass
Low softening point
(600 C)
High density
High refractive index
Reflects light raysand appears spar
kling
SiO2 (55%)
PbO( 30%)
K2O (10%)
Na2O ( 3%)
Al2 O 3 ( 2%)
Decorative items
Crystal glass-
wares
Lens
PrismsChandeliers
Ceramics
1. Ceramic is a manufactured substance made from clay that is dried and then
baked in a kiln at high temperature.
2. The main constituent of clay is aluminosilicate, (which consist of aluminium
oxide and silicon dioxide) with small quantities of sand and feldspar.
3. Kaolinite is an example of high
4. Red clay contains iron (III) oxide which gives the red colour .
5. General uses ceramics are as follows of :
very hard and strong but brittle
inert to chemical reaction
has a very high melting point
good electric and heat insulator
able to withstand compression
9.6 COMPOSITE MATERIAL
19
-
8/3/2019 22047806 Chemistry Form 4 Chapter 9
20/21
1. A composite material is a structural material formed by
combining two or more materials with different physical properties, producing a
complex mixture.
2. The composite material produced will have different properties
far more superior to the original materials.
3. The composite material produced are harder, stronger, lighter,
more resistant to heat and corrosion and also for specific purposes.
4. When composite material is formed, the weakness of the
components will not exist anymore.
20
-
8/3/2019 22047806 Chemistry Form 4 Chapter 9
21/21
Composite material Component Properties of
component
Properties of composite
Reinforced concrete
Concrete Hard but brittle,
With low tensile
strength
Stronger, higher tensile
strength, not so brittle,
does not corrode easily,
can withstand higher
applied forces and loads,
relatively cheaper
Steel Hard with high tensile
strength but expensive
and can corrode
Fibre optics
Glass of low
refractive index
Transparent, does not
reflect light rays.
Reflect light rays and
allow light rays to travel
along the fibreGlass of high
refractive index
Heavy, strong but
brittle and non-
flexible
Fibreglass
Glass Heavy, strong but
brittle and non-
flexible
Light, strong, tough,
resilient and flexible,
with high tensile strength
and not flammablePolyester plastic Light, flexible, elastic
but weak and
inflammable
Photochromic glass
Glass Transparent and notsensitive to light
Sensitive to light:darkness when light
intensity is high,
becomes clear when
light intensity is low
Silver chloride, or
silver bromide
Sensitive to light
Figure 9.9 Composite material and their new properties