chemistry chapt 8

:

.


: 404
:
:

content

- Appreciation 3
- Introduction & Objective 4
- 8.1 Alloy and Its Importance 5-7
- 8.2 Composition of Glass and Its Uses 8-10
- 8.3 Composition of Ceramics and Its Uses 11-14
- 8.4 Composite Materials and Its Importance 15-21
- Discussion 22
- Estimated time and Budget 23
- Reference 24

ii



We thank all the teachers who helped us by providing the

equipment that was necessary and vital, without which we


would not have been able to work effectively on this

assignment. We would also like to express our sincere

gratitude to our friends and parents, who stood by us and


encouraged us to work on this assignment.

3

INTRODUCTIONS AND OBJECTIVES

Alloy is a metallic substance composed of two or more
elements, as either a compound or a solution.

By the end of the chapter, students can :
• Define and classify alloys as mixtures.
• Compare and contrast the physical and chemical properties of alloys and elements.
• Determine the advantages of using alloys compared to pure substances.
• Learning and understanding the importances and uses of alloy in daily life.

4

8.1 Alloy and Its
Importance

• An alloy is a mixture of two or more elements with a certain fixed

composition where themain element is a metal.


Comparison of Properties of Alloy and Pure Metal

1. The properties of pure metals can
be improved by making them into

alloy.

2. The process of mixing atoms of

impurities with atoms of pure metal

by melting is called alloying.

3. Pure metals usually have high
densities, high melting and boiling
points, are good conductors of heat
and electricity, shiny (lustrous),
malleable and ductile.

5

● Ductility of metals 1.Due to the equal size of atoms and arranged in an
● Malleability of metals orderly manner, layers of pure metal atoms can slide
easily over one another when force is applied.


2. Therefore, metals are ductile (can be easily pulled into
fine wire)

1.There are some empty spaces between atoms in the
orderly arrangement of pure metal atoms.
2.With the same size of atoms, the layers of pure metal

atoms can easily slide to fill the empty spaces when
force is applied and form a new stucture.

6

• Arrangement of atom in an alloy

• An alloy is formed when foreign atoms

are mixed with the pure metal. These

foreign atoms are different in size

compared to the atoms in the pure
metal. Hence, the orderly arrangement

of atoms in a pure metal is disrupted.

This makes it difficult for the layers of
atoms in an alloy to slide over each

other when force is applied.

7

8.2 Composition of Glass and Its

Uses

8

Types of Glass

Fused Silica Glass
Fused silica glass is made from silica or silicon dioxide without adding any other
chemical.
•Silica requires high temperature around 1800°C to melt. Hence, fused silica glass

has a high melting point. This glass does not expand not contract much when there is
a large change in temperature. Fused silica glass is suitable to be used in making
telescope lens.

Soda-lime Glass
Soda-lime glass is made from silica, soda (sodium carbonate) and

limestone (calcium carbonate)

•Soda lowers the melting point of silica. Hence, soda glass has a
low melting point, around 1000°C. This glass is easily moulded

and used to make glass containers such as bottles and jugs.
However, this glass cannot withstand high temperatures and
can easily crack when subjected to sudden temperature change.

9

Borosilicate Glass
Borosilicate glass is made from silica, limestone, boron oxide
and aluminumoxide,

• Many laboratory glassware such as beakers and flasks are made

from borosilicate glass because of its resistance to heat. These

glassware do not crack easily when subjected to thermal stress
because of its low expansion coefficient. Borosilicate glass can be
removed from the refrigerator and heated immediately without
cracking.

Lead Crystal Glass
Lead crystal glass is made from silica, soda and lead(II) oxide,

•Lead replaces calcium to produce glass that is softer and denser.
Lead glass is heavier and has a high refractive index. This glass is

suitable to be used in making prisms.

10

8.3 Composition of Ceramics

and Its Uses

Ceramic is a solid made up of inorganic and non-metallic substances.

Ceramic is produced through the process of shaping and hardening by

using heating technique at a high temperature. Most ceramics contain

metal compounds, non-metal compounds or semi-metal compounds.

11

Type of Ceramics

Traditional

CerTarmadicitsional ceramics are mainly made

• from clay
• Generally, the main component of

traditional ceramics is silicate, a
compound that contains silicon, oxygen
and one or more metal
• The common way of preparing traditional
ceramics is by mixing clay with water to
produce a soft, mouldable mixture
• The moulded clay is then heated at a
very high temperature and left to cool for
the hardening process
• Ceramic that has been harden cannot be
melted again due to its extremely high
heat resistance

12

Advanced

CerAadmvaicnsced ceramics are made from inorganic


• compounds such as oxides, carbides and

nitrides

• Advanced ceramics have other particular
properties such as:

> resistant to abrasion
> withstand thermal shock
> better chemical durability
> has superconductivity properties

13

Ceramic Uses Application

Medication Transportation Energy
production
• Zirconia ceramic is used in
• Engine components in
• Ceramic is used
dental implants jet planes are made from
ceramics to make electrical
• Alumina ceramic is used to insulators in high
14 voltage areas
make knee bone such as power
stations
• Ceramic is used in Magnetic

Resonance Imaging (MRI)
machines because it has
superconductivity
properties

8.4 Composite Materials and

Its Importance

Composite materials are materials made from a combination of two or more non-
homogeneous substances, namely matrix substance and strengthening substance.
1.The matrix substance will surround and bind the strengthening substance together
2.Both components of a composite material (matrix substance and strengthening substance)

have different physical and chemical properties. When combined, the resulting composite
material has better properties than the original components

15

Composite Materials and Their Uses

• Reinforced concrete is produced when steel
bars or wire mesh (strengthening substance) is

immersed in concrete (matrix substance).

Reinforced concrete is widely used in the

construction of bridges, dams and buildings.

• Fibre glass is produced when plastic (matrix
substance) is strengthened with glass fibres

(strengthening substance). The composite material is

used to make helmets, car bumpers and printed
circuit boards.

16

• Optical fibre consists of three layers. The innermost

layer is the core that is made up of silica glass fibres
(strengthening substance). The core is encased kna
second layer or cladding that is made up of glass or
plastic (matrix substance). The outermost layer is
made of plastic that acts as a protective jacket
(matrix substance).

• Photochromic glass is formed when glass (matrix

substance) is combined with silver chloride and copper

chloride (strengthening substance). When exposed to

sunlight, photochromic glass darkens. This is due to the
formation of silver atoms that prevents the passage of
light. In dim light, copper chloride, in photochromic glass
catalyses the reverse process so that glass becomes
transparent again.

17

• Superconductorsuch as yttrium barium copper oxide, YBCO ceramic

is a composite material that has superconductivity properties other

than alloys. This superconductor is used to make electromagnets,

that are superconductor magnets or supermagnets. Superconductor
magnets are light and have strong magnetic force. Superconductor
magnets are used in particle accelerators and involved in Nuclear
Magnetic Resonance (NMR) machines and Magnetic Resonance
Imaging (MRI) machines.

18

Comparison and Difference in Properties of

Composite Materials and Their Original Components

Comparison in properties of reinforced concrete with its original components

• Concrete can withstand high compression forces but will break if subjected to high
stretching forces. Combination of concrete and steel bars or wire mesh can increase
the ability of the concrete to withstand compression forces.

19

Comparison in properties of fibre
glass with its original

coPmlapsoticnmenattrsix consists of plastic that, is


• weak, soft and easily burned. The

properties of plastic are reinforced by

adding glass fibre

Comparison in properties of optical

fibre with its original components

• Optical fibre has high compression

strength although the original


component that is glass gibre, is brittle

20

21

Discussion

1.What is the metal found in bronze?
2.What is the purpose of alloying pure iron?
3.What compound is used to make lenses and what is its main
component?
4.What are the advantages of using composite materials?

22

Estimated Time

and Budget

Estimated Time = A week / 7 days
Budget / Cost = RM 35 (data)

23

references

References

https://www.britannica.com

i. https://www.britannica.com



ii. 1202 Question Bank, Joanne Yeow Wei Chen, Pan
Asia Publications Sdn. Bhd.



iii.Masterclass SPM Chemistry,Yeap Tok Kheng,Fazilah
Hamzah,Salida Sani,Sasbadi Sdn. Bhd.



iv. Chemistry textbook form 4, Lim Kuok Chen,
Penerbitan Pelangi Sdn. Bhd.

24