37662871 Chemistry Form 4 Manufactured Substances in Industries

8/8/2019 37662871 Chemistry Form 4 Manufactured Substances in Industries

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CHEMISTRY

FORM 4

PORTFOLIO:

MANUFACTURED SUBSTANCES IN INDUSTRY

NAME : MOHAMAD FARIED BIN AHMAD ADNAN

FORM : 4 SC S

SUBJECT : CHEMISTRY

TOPIC : MANUFACTURED SUBSTANCES IN INDUSTRY

TEACHER : PN. YIP YIN LENG


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1.0. INT O TION

Nowadays, many industrial products are manufactured for the goodness of mankind.

The products are either made up from sulphuric acid, ammonia, alloys, synthetic polymers,

glass, ceramics or composite materials. These products can be made for many uses.

Therefore, we need to know how these products were manufactured, what are their physical

and chemical properties and others as well. Even though the products of these materials aredesigned for good uses, there are always the bad effects. We shall also go through the

environmental pollution caused by the by-product of these materials; during manufacture and

also during usage so that we can avoid the circumstances. By the way, in order to appreciate

the various industries in our country, we should understand these substances and products a

lot more.

The manufactured substances in industries that will be further discussed in this

assignment are:

Sulphuric Acid Ammonia Alloys Synthetic Polymers Glass & Ceramics Composite Materials

These substances are widely used in the industries in Malaysia. So, we may need to

understand some of the examples of the products.


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2.0. OBJE TIVE

The objectives of making this portfolio are mainly to appreciatethe manufactured

substances in Malaysia. Therefore, I have done all I could to get these objectives could befulfilled. However, the other objectives are:

To understand the manufacture of sulphuric acid

To synthesise the manufacture of ammonia and its saltsTo understand alloys

To compare the differences of alloy and its pure metals

To evaluate the details of synthetic polymers (natural occurring, uses,

environmental pollution)

To determine the different types, composition, properties and uses of glass

and ceramics

To understand composite metals & evaluate their uses

To appreciate various synthetic industrial materials


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3.0. GATHERING F INF RMATI N

3.1. S l i A i

Di

: The Sul

huri Aci ; H2SO4

3.1.1. M S l i A i , H2S 4 I I s

Sul huric aci i produced from sulphur, oxygen and water via the conventionalContact

Process (DCDA) orthe Wet Sulphuric Acid Process (WSA).

Co P o ss (DCDA)

Figure: Manufacture Of H2SO4 In Industry; Contact Process

In the first step, sulphuris burned to produce sulphur dioxide.

o S (s) + O2 (g) SO2 (g)This is then oxidized to sulphurtrioxide using oxygen in the presence of a vanadium (V)

oxide catalyst.

o 2 SO2 (g) + O2 (g) 2 SO3 (g) (in presence of V2O5)


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The sulphur trioxide is absorbed into 97-98% H2SO4 to form oleum (H2S2O7), also known asfuming sulphuric acid.

o H2SO4 (l) + SO3 H2S2O7 (l)The oleum is then diluted with water to form concentrated sulphuric acid.

o H2S2O7 (l) + H2O (l) 2 H2SO4 (l)Note that directly dissolving SO3 in water is not practical due to the highly exothermic natureof the reaction between sulphur trioxide and water. The reaction forms a corrosive aerosol

that is very difficult to separate, instead of a liquid.

o SO3 (g) + H2O (l) H2SO4 (l)Wet Sulphuric Acid Pr cess (WSA)

In the first step, sulphur is burned to produce sulphur dioxide:

o S(s) + O2(g) SO2(g)Or, alternatively, hydrogen sulphide (H2S) gas is incinerated to SO2 gas:

o 2 H2S + 3O2 2 H2O + 2 SO2 (518 kJ/mol)This is then oxidi ed to sulphur trioxide using oxygen with vanadium (V) oxide as catalyst:

o 2 SO2 + O2 2 SO3 (99 kJ/mol)The sulphur trioxide is hydrated into sulphuric acid H2SO4:

o SO3 + H2O H2SO4(g) (101 kJ/mol)The last step is the condensation of the sulphuric acid to liquid 9798% H2SO4:

o H2SO4(g) H2SO4(l) (69 kJ/mol)Other Meth ds

Another method is the less well-known metabisulphite method, in which

metabisulphite in placed at the bottom of a beaker, and 12.6 molar concentrations

hydrochloric acid is added. The resulting gas is bubbled through nitric acid, which will

release brown/red vapours. The completion of the reaction is indicated by the ceasing of the

fumes. This method does not produce an inseparable mist, which is quite convenient.

Sulphuric acid can be produced in the laboratory by burning sulphur in air and dissolving thegas produced in a hydrogen peroxide solution.

o SO2 + H2O2 H2SO4Another method is to react hydrochloric acid with copper II sulphate:

o2 HCl + Cu

SO4 H2

SO4 + CuCl2

Prior to 1900, sulphuric uric acid was manufactured by the chamber process. As late

as 1940, up to 50% of sulphuric acid manufactured in the United States was produced by

chamber process plants.


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3.1.2. TheEnvir nmental PollutionbytheBy-ProductOfH2SO

Sulphur dioxide; SO2 is one of the by-product in the manufacture ofSulphuric acid;

H2SO4. Sulphur dioxide causes environmental pollution. Almost all sulphur dioxides in air

come from the burning of fossil fuels containing sulphur. The effect to the environment was

the acid rain.

Acid Rain

Diagram: Acid Rain

Natural rainwater has a pH of 5.4. Acid rain occurs when the pH of the rain is

between 2.4 and 5.0. This is due to the reaction of sulphur dioxide with the rainwater.o 2SO2(g) + O2(g) + 2H2O(l) 2H2SO4(aq)

Sulphur dioxide is release through chimneys of factories. The sulphur dioxide react

with water and oxygen to form acid rain in the clouds. The acid rain causes:

1. Buildings and metal structures corrode2. The trees in forest to destroy3. Lakes and rivers become acidic (kills fish and organisms)4. The pH of soil decreases5. Salts are leached out of the top soil


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3.2. Ammo i

Diagram: The Ammonia; NH3

3.2.1. T P si l & C mi l P o i s Ammo i , NH3

P si l P o i s

y Ammonia is a colourless gas.y It has a pungent odour with and an al aline or soapy taste. When inhaled suddenly,itbrings tears into the eyes.y Itis lighterthan air and is therefore collected by the downward displacement of air.y Itis highly soluble in water: One volume of water dissolves about 1300 volumes of

ammonia gas. Itis due to its high solubility in waterthatthe gas cannot be collected

over water.y It can be easily li uefied at room temperature by applying a pressure of about 8-10

atmosphere.y Li uid ammonia boils at 239.6 K (- 33.5C) under one atmosphere pressure. It has a

high latent heat of vaporization (1370 J per gram) and is therefore used inrefrigeration plants ofice making machines.

y Li uid ammonia freezes at 195.3 K (-77.8C) to give a white crystalline solid.C mi l P o i s

The ammonia molecule has a trigonal pyramidal shape with a bond angle of 107.8 as

shown above, as predicted by the valence shell electron pair repulsion theory (VSEPR). The

central nitrogen atom has five outer electrons with an additional electron from each hydrogen

atom. This gives a total of eight electrons, or four electron pairs which are arranged

tetrahedrally. Three ofthese electron pairs are used as bond pairs, which leaves one lone pair

of electrons. The lone pair of electrons repel more strongly than bond pairs, therefore the

bond angle is not 109.5 as expected for a regulartetrahedral arrangement, butis measured at

107.8.

The nitrogen atom in the molecule has a lone electron pair, which makes ammonia abase, a proton acceptor. This shape gives the molecule a dipole moment and makes it polar.

The molecule's polarity and, especially, its ability to form hydrogen bonds, making ammonia

highly miscible with water. Ammonia is moderately basic, a 1.0 M aqueous solution has a pH

of 11.6 and if a strong acid is added to such a solution untilthe solution is neutral (pH = 7),

99.4% ofthe ammonia molecules are protonated. Temperature and salinity also affectthe

proportion of NH4+. The latter has the shape of a regulartetrahedron and is isoelectronic with

methane. Itis known to have the highest specific heat capacity of any substance.


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3.2.2. T M NH3 I I s

Ammonia; NH3is manufactured in industries through the Haber Process which combines the

nitrogen gas; N2 from air with hydrogen gas; H2 derived mainly from natural gas.

H P o ss

Figure: Manufacture Of NH3 In Industries; Haber Process

The manufacture of ammonia by Haber's process involves the direct combination of

nitrogen and hydrogen. The mixture of 1 volume of nitrogen gas; N2to 3 volume of hydrogen

gas; H2is passed through the reactor. The mixture is compressed to a high pressure of 200

atm at a temperature about 450C. Itis then passed through layers ofiron catalystto speed up

the rate of reaction.

o N2(g) + H2(g) NH3(l) (H = -92kJ)Ammonia thatis formed is then liquefied and separated to get a better yield. The

production of ammonia gives out heat. However, the unreacted nitrogen gas and hydrogengas are recycled and passed backto the reactor again;together with the new source of N2 and

H2. This reaction is: reversible, exothermic, and proceeds with a decrease in volume. About

98% of N2 and H2 are converted into ammonia. According to the Le Chatelier's principle, the

favourable conditions forthe formation of ammonia are:

y Low T mThe temperature should be remain as low as possible, (although at unusually low

temperatures, the rate of reaction becomes slow). It has been found thatthe temperature,

which optimizes the yield of ammonia forthe reaction, is maximum at about 500C.

y Hig P ssSince Haber's process proceeds with a decrease in volume, itis favoured by high

pressure. In actual practice, a pressure of 200 - 900 atmospheres is employed.

y C l sA catalystis usually employed to increase the speed ofthe reaction. Finely divided

iron containing molybdenum or alumina is used as a catalyst. Molybdenum or alumina(Al2O3) acts as a promoter and increases the efficiency ofthe catalyst. A mixture ofiron

oxide and potassium aluminates has been found to work more effectively.


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3.2.3. The PreparationOfAmmonium Salts In SchoolLaboratory

Ammonium Chloride

The ammonium chloride salt is prepared by treating hydrochloric acid with ammonia.

The solution obtained is evaporated to obtain the salt of ammonium chloride. This salt is also

called "Sal Ammoniac".

Ammonium Sulphate

Ammonium sulphate is prepared by treating sulphuric acid with ammonia.

The solution obtained is then evaporated to get the ammonium sulphate salt.

Ammonium Nitrate

Ammonium nitrate prepared by treating nitric acid with ammonia.

The ammonium nitrate solution obtained is evaporated to get the salt.

Ammonium Carbonate (Sal Volatile)

When a mixture of ammonium sulphate and powdered calcium carbonate are heated and the

vapour condensed, ammonium carbonate or sal volatile is obtained.


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3.3. Allo s

Diagram: A Metal Alloy (Steel Wire)

3.3.1. Allo s & Aim M ki g Allo s

An alloy is a partial or complete solid solution of one or more elements in a metallic

matrix. Complete solid solution alloys give single solid phase microstructure, while partial

solutions give two or more phases that may be homogeneous in distribution depending on

thermal (heattreatment) history. Alloys usually have different properties from those ofthe

component elements. Alloys' constituents are usually measured by mass. The main aim of

making alloys is to produce a stronger metal from the constituent pure metals. Therefore, the

alloy can be made into many more uses afterthe process as itis stronger and has much more

resistance.

3.3.2. T Com iso P o i s Allo s & T i P M ls

Diagram: An Alloy (Two Different Pure Metals Combined)

Alloying one metal with other metal(s) or non metal(s) often enhances its properties.For example, steelis strongerthan iron, its primary element. The physical properties, such as

density, reactivity, Young's modulus, and electrical and thermal conductivity, of an alloy maynot differ greatly from those ofits elements, but engineering properties such as tensile

strength and shear strength may be substantially different from those ofthe constituentmaterials. This is sometimes due to the sizes ofthe atoms in the alloy, since larger atoms

exert a compressive force on neighbouring atoms, and smaller atomsexert a tensile force on

their neighbours, helping the alloy resist deformation. Sometimes alloys may exhibit marked

differences in behaviour even when small amounts of one element occur. For example,

impurities in semi-conducting ferromagnetic alloys lead to different properties, as first

predicted by White, Hogan, Suhl, Tian Abrie and Nakamura.


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Some alloys are made by melting and mixing two or more metals. Bron e, an alloy ofcopper and tin, was the first alloy discovered, during the prehistoric period now known as the

Bron e Age; it was harder than pure copper and originally used to make tools and weapons,but was later superseded by metals and alloys with better properties. In later times bron e has

been used for ornaments, bells, statues, and bearings. Brass is an alloy made from copper and

inc.

Unlike pure metals, most alloys do not have a single melting point, but a melting

range in which the material is a mixture of solid and liquid phases. The temperature at which

melting begins is called the solidus, and the temperature when melting is just complete is

called the liquidus. However, for most alloys there are a particular proportion of constituents

(in rare cases too) the eutectic mixture which gives the alloy a unique melting point.

3.3.3. Examples OfAlloy & The Uses

Examples Of

AlloyComposition Properties Uses

Bronze 90% Copper 10% Tin

Hard & Strong Does Not CorrodeEasily

Shiny Surface In the building of statues &monuments In the making of medals,

swords & artistic materials

Brass 70% Copper 30% Zinc Harder ThanCopper In the making of musicalinstruments and kitchenware

Steel 99% Iron 1% Carbon Hard & Strong

In the construction of bridgesand buildings

In the building of the body ofcars and railway tracks

Stainless Steel

74% Iron 8% Carbon 18%

Chromium

Shiny Strong Does Not Rust

In the making of cutlery In the making of surgicalinstruments

Duralumin

93%Aluminium

3% Copper 3%

Magnesium

1%Manganese

Light Strong In the building of the body ofaeroplanes and bullet trains

Pe ter

96% Tin 3% Copper

1% Antimony

Lustre Shiny S

trong

In the making of souvenirsTable: ExamplesOf Alloys & Their Uses


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3.4. S i Pol m s

Diagram: Atomic View Of Synthetic Polymers

3.4.1. N l i g Pol m s (Bio ol m s)

Diagram: Atomic View Of Biopolymers

Natural polymers or biopolymers are polymers produced by living organisms.

Cellulose, starch, chitin, proteins, peptides, DNA and RNA are all examples of biopolymers,in which the monomeric units, respectively, are sugars, amino acids, and nucleotides.

Cellulose is both the most common biopolymer and the most common organic

compound on Earth. About 33 percent of all plant matteris cellulose. E. G. The cellulose

content of cotton is ~ 90 percent and that of wood is ~ 50 percent.

Some biopolymers are biodegradable. Thatis, they are broken down into CO2 and

water by microorganisms. In addition, some ofthese biodegradable biopolymers are

compostable. Thatis, they can be putinto an industrial composting process and will breakdown by 90% within 6 months. Biopolymers that do this can be marked with a 'compostable'

symbol, under European Standard EN 13432 (2000). Packaging marked with this symbol can

be putinto industrial composting processes and will break down within 6 months (orless).

An example of a compostable polymeris PLA film under 20 m thick: films which are

thickerthan that do not qualify as compostable, even though they are biodegradable. A home

composting logo may soon be established which will enable consumers to dispose of

packaging directly onto their own compost heap.


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A major but defining difference between polymers and biopolymers can be found in

their structures. Polymers, including biopolymers, are made of repetitive units calledmonomers. Biopolymers often have a well defined structure, though this is not a defining

characteristic (example: ligno-cellulose): The exact chemical composition and the sequence

in which these units are arranged is called the primary structure, in the case of proteins. Many

biopolymers spontaneously fold into characteristic compact shapes (see also "protein folding"

as well as secondary structure and tertiary structure), which determine their biological

functions and depend in a complicated way on their primary structures. Structural biology is

the study of the structural properties of the biopolymers. In contrast most synthetic polymers

have much simpler and more random (or stochastic) structures. This fact leads to a molecular

mass distribution that is missing in biopolymers. In fact, as their synthesis is controlled by a

template directed process in most in vivo systems all biopolymers of a type (say one specificprotein) are all alike: they all contain the similar sequences and numbers of monomers and

thus all have the same mass. This phenomenon is called monodispersity in contrast to thepolydispersity encountered in synthetic polymers. As a result biopolymers have a

polydispersity index of 1.

3.4.2. Synthetic Polymers

Figure:Synthetic Polymer

Synthetic Polymers are defined as manmade polymers or plastics. First human madeplastic was invented by Alexander Parks in 1855. It was then called Parke sine (later on

Celluloid).

Polymers are made of small repeating structural units called monomers. Polyethylene

is the simplest polymer, which consists of ethene (ethylene) as monomer units and the

corresponding linear polymer is called high density polyethylene (HDPE).Many polymeric

materials having chain-like structures similar to polyethylene are known. Synthetic polymers

are often referred to as "plastics", well-known are polyethylene and nylon.

Polymers formed by a straightforward linking together of monomer units, with no loss

or gain of material, are called addition polymers or chain-growth polymers. All of these are

synthetic polymers. Thus Synthetic polymers are useful to human being in every aspect of

life. Almost all the substances we use for our convenience are made of synthetic polymers.


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3.4.3. Synthetic Polymers & Their Uses InDailyLife

Synthetic Polymers Formula Monomer Uses

Polyethylene Low Density (LDPE)

(CH2-CH2)n ethyleneCH2=CH2

Used in film wrap,plastic bags

Polyethylene

Hi hDensity (HDPE)(CH2-CH2)n

ethylene

CH2=CH2

Used in electrical

insulation, bottles & toys

Poly(Vinyl Chloride)

(PVC)(CH2-CHCl)n

vinyl chloride

CH2=CHCl

Used in pipes, siding &

flooring

Poly(Vinylidene

chloride)

(Saran A)

(CH2-CCl2)nvinylidene chloride

CH2=CCl2

Used in seat covers &

films

Polystyrene

(PS)[CH2-CH(C6H5)]n

styrene

CH2=CHC6H5

Used in toys, cabinets &

packaging

Polyacrylonitrile(PAN, Orlon, Acrilan) (CH2-CHCN)n acrylonitrileCH2=CHCN Used in rugs, blankets &clothing

Polytetrafluoroethylene

(PTFE, Teflon)(CF2-CF2)n

tetrafluoroethylene

CF2=CF2

Used in non-stick

surfaces / electrical

insulation

Poly (Vinyl Acetate)

(PVAc)(CH2-CHOCOCH3)n

vinyl acetateCH2=CHOCOCH3

Used in latex paints &adhesives

Nylon -

Hexane-1, 6 diol

Ben ene, 4-

dicarboxylic acid

Used in clothing, sails

and ropes

Perspex - MethylmethacrylateSafety glass, reflectors,

traffic lights and lens

cis-Polyisoprene

Natural Rubber

[CH2-CH=C(CH3)-CH2]n

isoprene

CH2=CH-

C(CH3)=CH2

Requires vulcani ation

for practical use andvulcani ed rubber is used

in tyres

Polychloroprene

(cis + trans) (Neoprene)[CH2-CH=CCl-CH2]n

chloroprene

CH2=CH-CCl=CH2

It is a synthetic rubber

and is oil resistant so

used in matsTable: ExamplesOfSynthetic Polymers & Their Uses

3.4.4. TheEffectOfThe Uses OfSynthetic Polymers To TheEnvironment

Plastic, one of the products of synthetic polymers is one of the new and worstchemical materials which cause serious environment pollution and is certainly a cancer innature. Plastic is regarded to be a biological ha ard since it is almost non- degradable. Tonnes

of plastic waste are dumped everyday into the earth all over the world. Plastic pollution isdestroying the worlds ocean ecosystems as a lot of waste is flushed into the ocean.


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Plastic is used very commonly in the world because they are cheap, easy to make andthey will last long as well. But sorry to say, these useful qualities make plastic a real menace

to the environment. As it is so cheap that people discards it soon especially carrybags anddisposable bottles. As these materials are long-lasting and difficult to decompose, it persists

in the earth for many centuries resulting in enormous environment pollution. As a result of

urbani ation, most of the pollution is concentrated in cities.

Synthetic polymers can easily be moulded into different shapes, while some can be

made into thin film like bits and pieces, which became very accepted in form of durable and

disposable carrybags and packing materials. These materials when thrown out after use

remains in the soil in the same form as it is non-biodegradable.

According to latest studies, up to 105 million tonnes of plastic is produced yearly in

the world, out of which only 2.5 million tonnes is produced in India. The use of plastic

(synthetic polymers) in Western and European countries is averaging 70 kg per person per

year, while in India it is 4 kg per person per year. Anyhow its on the rise all over the world.

The amount of synthetic polymer waste in the ocean is rapidly growing as well. Close to 85%

of objects found in the beaches contains traces of polymers. Most of the rubbish found on thebeaches is packaging materials. This is a real threat to the life and habitat of marine wild life

especially turtles as well as seabirds. In reality, synthetic polymer pollution is a much bigger

threat than o one hole and global warming.

3.5. Glass & Ceramics

Diagram:Glass Diagram:Ceramics

3.5.1. DifferentTypes, Composition, Properties & Uses OfGlass

Types & Uses

Glass is an amorphous (non-crystalline) solid material. Glasses are typically brittle,

and often optically transparent. Glass is commonly used for windows, bottles, and eyewear;

examples of glassy materials include soda-lime glass, borosilicate glass, acrylic glass, sugar

glass, Muscovy-glass, and aluminium oxynitride. The termglass developed in the late Roman

Empire. It was in the Roman glassmaking centre at Trier, now in modern Germany, that the

late-Latin termglesum originated, probably from a Germanic word for a transparent, lustrous

substance.


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Strictly speaking, a glass is defined as an inorganic product of fusion which has beencooled through its glass transition to the solid state without crystallising. Many glasses

contain silica as their main component andglass former. The term "glass" is, however, oftenextended to all amorphous solids (and melts that easily form amorphous solids), including

plastics, resins, or other silica-free amorphous solids. In addition, besides traditional melting

techniques, any other means of preparation are considered, such as ion implantation, and the

sol-gel method. Commonly,glass science and physics deal only with inorganic amorphoussolids, while plastics and similar organics are covered by polymer science, biology and

further scientific disciplines. Glass plays an essential role in science and industry. The optical

and physical properties of glass make it suitable for applications such as flat glass, container

glass, optics and optoelectronics material, laboratory equipment, thermal insulator (glass

wool), reinforcement fibre (glass-reinforced plastic, glass fibre reinforced concrete), and art.

Nearly all commercial glasses fall into one of six basic categories or types. These

categories are based on chemical composition. Within each type, except for fused silica, there

are numerous distinct compositions:

y Soda-lime glass is the most common (90% of glass made), and least expensiveform of glass. It usually contains 60-75% silica, 12-18% soda, 5-12% lime.Resistance to high temperatures and sudden changes of temperature are not good

and resistance to corrosive chemicals is only fair.

y Lead glass has a high percentage of lead oxide (at least 20% of the batch). It isrelatively soft, and its refractive index gives a brilliance that may be exploited by

cutting. It is somewhat more expensive than soda-lime glass and is favoured for

electrical applications because of its excellent electrical insulating properties.

Thermometer tubing and art glass are also made from lead-alkali glass, commonly

called lead glass. This glass will not withstand high temperatures or sudden

changes in temperature.

y Borosilicate glass is any silicate glass having at least 5% of boric oxide in itscomposition. It has high resistance to temperature change and chemical corrosion.

Not quite as convenient to fabricate as either lime or lead glass, and not as low incost as lime, borosilicate's cost is moderate when measured against its usefulness.

Pipelines, light bulbs, photo chromic glasses, sealed-beam headlights, laboratoryware, and bake ware are examples of borosilicate products.

y Aluminosilicate glass has aluminium oxide in its composition. It is similar toborosilicate glass but it has greater chemical durability and can withstand higher

operating temperatures. Compared to borosilicate, aluminosilicates are more

difficult to fabricate. When coated with an electrically conductive film,

aluminosilicate glass is used as resistors for electronic circuitry.y Ninety-six percent silica glass is a borosilicate glass, melted and formed by

conventional means, then processed to remove almost all the non-silicate elements

from the piece. By reheating to 1200C the resulting pores are consolidated. Thisglass is resistant to heat shock up to 900C.

y Fused silica glass is pure silicon dioxide in the non-crystalline state. It is verydifficult to fabricate, so it is the most expensive of all glasses. It can sustain

operating temperatures up to 1200C for short periods.


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Composition & Properties

There are three classes of components for oxide glasses: network formers,

intermediates, and modifiers. The network formers (silicon, boron, and germanium) form ahighly cross-linked network of chemical bonds. The intermediates (titanium, aluminium,

irconium, beryllium, magnesium, inc) can act as both network formers and modifiers,

according to the glass composition. The modifiers (calcium, lead, lithium, sodium,

potassium) alter the network structure; they are usually present as ions, compensated by

nearby non-bridging oxygen atoms, bound by one covalent bond to the glass network and

holding one negative charge to compensate for the positive ion nearby. Some elements can

play multiple roles; e.g. lead can act both as a network former (Pb4+

replacing Si4+

), or as a

modifier.

The presence of non-bridging oxygen lowers the relative number of strong bonds inthe material and disrupts the network, decreasing the viscosity of the melt and lowering the

melting temperature. The alkaline metal ions are small and mobile; their presence in glassallows a degree of electrical conductivity, especially in molten state or at high temperature.

Their mobility however decreases the chemical resistance of the glass, allowing leaching bywater and facilitating corrosion. Alkaline earth ions, with their two positive charges and

requirement for two non-bridging oxygen ions to compensate for their charge, are much lessmobile themselves and also hinder diffusion of other ions, especially the alkalis. The most

common commercial glasses contain both alkali and alkaline earth ions (usually sodium and

calcium), for easier processing and satisfying corrosion resistance. Corrosion resistance of

glass can be achieved by dealkali ation, removal of the alkali ions from the glass surface by

reaction with e.g. sulphur or fluorine compounds. Presence of alkaline metal ions has also

detrimental effect to the loss tangent of the glass, and to its electrical resistance; glasses for

electronics (sealing, vacuum tubes, lamps...) have to take this in account.

Addition of lead (II) oxide lowers melting point, lowers viscosity of the melt, and

increases refractive index. Lead oxide also facilitates solubility of other metal oxides and

therefore is used in coloured glasses. The viscosity decrease of lead glass melt is very

significant (roughly 100 times in comparison with soda glasses); this allows easier removal of

bubbles and working at lower temperatures, hence its frequent use as an additive in vitreous

enamels and glass solders. The high ionic radius of the Pb2+

ion renders it highly immobile inthe matrix and hinders the movement of other ions; lead glasses therefore have high electrical

resistance, about two orders of magnitude higher than soda-lime glass (108.5

vs. 106.5

Ohmcm, DC at 250 C). For more details, see lead glass.

Addition of fluorine lowers the dielectric constant of glass. Fluorine is highlyelectronegative and attracts the electrons in the lattice, lowering the polari ability of thematerial. Such silicon dioxide-fluoride is used in manufacture of integrated circuits as an

insulator. High levels of fluorine doping lead to formation of volatile SiF2O and such glass is

then thermally unstable. Stable layers were achieved with dielectric constant down to about

3.53.7.


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3.5.2. The Composition, Properties & Uses OfCeramics

Ceramics can be defined as heat-resistant, non-metallic, inorganic solids that are

(generally) made up of compounds formed from metallic and non-metallic elements.

Although different types of ceramics can have very different properties, in general ceramicsare corrosion-resistant and hard, but brittle. Most ceramics are also good insulators and can

withstand high temperatures. These properties have led to their use in virtually every aspect

of modern life.

Some ceramics are composed of only two elements. For example, alumina is

aluminium oxide, Al2O3; irconia is irconium oxide, ZrO2. Ceramics are good insulators and

can withstand high temperatures. A popular use of ceramics is in artwork. Silicon dioxide;

SiO2 and other ceramic materials, including many minerals, have complex and even variable

compositions. For example, the ceramic mineral feldspar, one of the components of granite,

has the formula KAlSi3O8.

The chemical bonds in ceramics can be covalent, ionic, or polar covalent, depending

on the chemical composition of the ceramic. When the components of the ceramic are a metal

and a non-metal, the bonding is primarily ionic; examples are magnesium oxide (magnesia),

MgO, and barium titanate, BaTiO3. In ceramics composed of a metalloid and a non-metal,

bonding is primarily covalent; examples are boron nitride, BN, and silicon carbide, SiC. Most

ceramics have a highly crystalline structure, in which a three-dimensional unit, called a unit

cell, is repeated throughout the material. For example, magnesium oxide crystalli es in therock salt structure. In this structure, Mg 2+ ions alternate with O

2 ions along each

perpendicular axis.

Most ceramics are hard, chemically inert, refractory (can withstand very high heatwithout deformation), and poor conductors of heat and electricity. Ceramics also have low

densities. These properties make ceramics attractive for many applications. Ceramics areused as refractories in furnaces and as durable building materials (in the form of bricks, tiles,

cinder blocks, and other hard, strong solids). They are also used as common electrical and

thermal insulators in the manufacture of spark plugs, telephone poles, electronic devices, and

the nose cones of spacecraft. However, ceramics also tend to be brittle. A major difficulty

with the use of ceramics is their tendency to acquire tiny cracks that slowly become larger

until the material falls apart. To prevent ceramic materials from cracking, they are often

applied as coatings on inexpensive materials that are resistant to cracks.

Composite materials that contain ceramic fibres embedded in polymer matrices

possess many of the properties of ceramics; these materials have low densities and areresistant to corrosion, yet are tough and flexible rather than brittle. They are used in tennis

rackets, bicycles, and automobiles. Ceramic composites may also be made from two distinct

ceramic materials that exist as two separate ceramic phases in the composite material. Cracks

generated in one phase will not be transferred to the other. As a result, the resistance of thecomposite material to cracking is considerable. Composite ceramics made from diborides

and/or carbides of irconium and hafnium mixed with silicon carbide are used to create thenose cones of spacecraft. Break-resistant cookware (with outstanding thermal shock

resistance) is also made from ceramic composites.


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Although most ceramics are thermal and electrical insulators, some, such as cubic

boron nitride, are good conductors of heat, and others, such as rhenium oxide, conductelectricity as well as metals. Indium tin oxide is a transparent ceramic that conducts

electricity and is used to make liquid crystal calculator displays. Some ceramics are

semiconductors, with conductivities that become enhanced as the temperature increases. For

example, silicon carbide, SiC, is used as a semiconductor material in high temperatureapplications.

3.6. Composite Materials

Diagram: Examples OfComposite Materials (E-Glass Cloth & Plywood)

3.6.1. Composite Materials

Composite are formed by combining two or more materials in such a way that the

constituents of the composite materials are still distinguishable, and not fully blended;

producing a complex mixture. One example of a composite material is reinforced concrete,

which uses cement as a binding material in combination with gravel as a reinforcement. In

many cases, concrete uses rebar as a second reinforcement, making it a three-phasecomposite, because of the three elements involved.

Composite materials take advantage of the different strengths and abilities of different

materials. In the case of mud and straw bricks, for example, mud is an excellent binding

material, but it cannot stand up to compression and force well. Straw, on the other hand, is

well able to withstand compression without crumbling or breaking, and so it serves to

reinforce the binding action of the mud. Humans have been creating composite materials to

build stronger and lighter objects for thousands of years.

The majority of composite materials use two constituents: a binder or matrix andreinforcement. The reinforcement is stronger and stiffer, forming a sort of backbone, while

the matrix keeps the reinforcement in a set place. The binder also protects the reinforcement,which may be brittle or breakable, as in the case of the long glass fibres used in conjunction

with plastics to make fibreglass. Generally, composite materials have excellentcompressibility combined with good tensile strength, making them versatile in a wide range

of situations.

Engineers building anything, from a patio to an airplane, look at the unique stresses

that their construction will undergo. Extreme changes in temperature, external forces, and

water or chemical erosion are all accounted for in an assessment of needs. When building an


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aircraft, for example, engineers need lightweight, strong material that can insulate and protectpassengers while surfacing the aircraft. An aircraft made of pure metal could fail

catastrophically if a small crack appeared in the skin of the airplane. On the other hand,aircraft integrating reinforced composite materials such as fibreglass, graphite, and other

hybrids will be stronger and less likely to break up at stress points in situations involving

turbulence.

Many composites are made in layers or plies, with a woven fibre reinforcement

sandwiched between layers of plastic or another similar binder. These composite materials

have the advantage of being very mouldable, as in the hull of a fibreglass boat. Composites

have revolutioni ed a number of industries, especially the aviation industry, in which the

development of higher quality composites allows companies to build bigger and better

aircraft.

3.6.2. Examples OfComposite Materials & Their Uses

Examples Of

Composite MaterialsUses

Reinforced Concrete Construction of framework for highways & bridges Used in the construction of high-rise buildings

Superconductors

To make more efficient generators, transformers & amplifiers To produce more efficient electric cables, computer parts &

stronger and lighter electromagnets

FibreOptic Transmits data in the form of light in telecommunicationFibre Glass

Water & food storage containers Boats & fishing rods Car bodies Roofing & swimming pool linings

Photochromic Glass

Photochromic optical lens & camera lens To make car windshields, optical switches, information display

panels

The building of the light intensity metals3.6.3. Superconductor

In normal electrical conductors such as copper metal, the existence of resistance

causes the loss of electrical energy as heat. Furthermore, resistance increases as temperatureincreases. Superconductors can conduct electricity with ero resistance when they are cooled

to extremely low temperatures. Thus, superconductors conduct electricity without any loss ofenergy.

Metals such as copper can only achieve superconductivity at a very low temperature

(known as the transition temperature). This low temperature can only be achieved using

liquid helium which is very expensive. When a mixture of copper (II) oxide, barium oxideand yttrium oxide is heated up, a type of ceramic with the formula YBa2Cu3O7 is produced.

This type of ceramic, known as perovkite or YBCO, can attain superconductivity at 90K.This temperature can easily be attained by using the cheaper liquid nitrogen.


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The metal oxides (CuO, Y2O3 and BaO) are all electrical insulators. However, whenthey are combined to form a composite, the composite is a superconductor that can conduct

very high current over long distance without any loss of energy. Superconductors are used tomake more efficient generators, magnetic energy-storage systems, transformers, electric

cables, amplifiers and computer parts. They are also used in magnetic resonance imaging

(MRI); a type of medical imaging device. Superconductors are also used to make stronger,

lighter and more powerful electromagnets. High speed levitated trains (trains that float on therailway track) involve the use of electromagnets as superconductors.

3.6.4. FibreOptic Cables & Fibre Glass

FibreOptic Cables (Optical Fibres)

Optical fibres are bundles of glass tubes with very small diameters. They are finerthan human hair and are very flexible. Fibre optics is a composite material that can transmit

electronic data or signals, voice and images on the digital format; in the form of light along

the fine glass tubes at great speed. A fibre optic consists of a core of glass of higher refractiveindex enclosed by a cladding of lower refractive index. A light wave entering the fibre will

travel along the glass tubes due to total internal reflection.

In the field of telecommunications, fibre optic is used to replace copper wire in long

distance telephone lines, mobile phones, video cameras and to link computers within local

area networks (LAN). Fibre optic uses light instead of electrons to carry data. Fibre optic

carry more data (higher transmission capacity) with less interference, has a higher chemical

stability and a lower material costs compared to metal communication cables such as copper.

Fibre optics can also send signals faster than metal cables and occupies less space.

In the field of medicine, a laser beam can be channelled through fibre optics in

operations to remove unwanted tissues. Fibre optics is also used in endoscopes: instrumentsthat are inserted into the body through the nose, mouth or ear; for doctors to examine theinternal organs. Nevertheless, fibre optic is also used in instruments to inspect the interiors of

manufactured products.

Fibre Glass

Plastic is light (with low density), elastic, flexible, but is brittle, not very strong andinflammable. Glass is hard and strong but is brittle, heavy (with relatively high density) and

has a low compressive strength. When glass fibre filaments are embedded in polyester resin

(a type of plastic), fibre glass which is strong, tough, resilient, flexible with a high tensile

strength is produced. It can also be easily coloured, moulded and shaped.

This material can also be bent without cracking. It is also very light (low in density)

and has very good strength ratio, impermeable to water and is not inflammable (does not

catch fire easily). Fibreglass is an ideal material for making water storage tanks, boat hulls,

swimming pool linings, food container, fishing rods, car bodies, rackets, furniture and also

helmets.


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3.6.5. Photochromic Glass

Glass is transparent and is not sensitive to light intensity. Silver chloride or silver

bromide is sensitive to light. When exposed to light, these compounds decompose to form

dark silver particles.

In photochromic glass, silver chloride (AgCl) or silver bromide (AgBr) is embedded

into the structure of glass. Photochromic glass has the ability to change colour and become

darker when exposed to ultraviolet light. This process occurs as a result of silver halide

crystals within the glass clustering together to absorb and filter light. Silver halides are

converted to silver and the glass darkens. The photochromic glass will automatically become

clear again when the light intensity is lowered, whereby silver is converted back to silver

halides. Photochromic glass is used to make lenses that change from light to dark, eliminating

the necessity for a separate pair of sunglasses. It is also used to make camera lens, car

windshields, information display panels, light intensity meters and also optical switches.


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4.0. CONCLUSION

Throughout this research, I found that continuous research and development (R&D) is

required to produce better materials used to improve our standard of living. Therefore, as we

live in a changing world, our society is becoming more complex. New materials are required

to overcome new challenges and problems we face in our daily lives. Synthetic materials are

developed constantly due to limitation and shortage of natural materials.

Therefore, new technological developments are used by scientists to make new

discoveries. New materials for clothing, shelter, tools and communication to improve our

daily life are developed continuously for the well-being of mankind. New needs and new

problems will stimulate the development of new synthetic materials. For examples, the use of

new plastic composite material will replace metal in making of a stronger but lighter car

bodies. This will save fuel and improve speed. Plastic composite materials may one day be

used to make organs for organs transplant in human bodies. This will become a necessity

with the shortage of human organ donors. New superconductors made from composite

materials are developed.

In addition, the understanding of the interaction between different chemicals is

important for both the development of new synthetic materials and the disposal of such

synthetic materials as waste. Hence, a responsible and systematic method of handling these

wastes of synthetic materials and their by-products is important to prevent environmental

pollution. Other than that, the recycling and development of environmental friendly synthetic

material should be enforced to avoid any further pollution.


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5.0. REFERENCES

www.wikipedia.org

www.google.com/search

http://www.google.com.my/imghp?hl=en&tab=wi

www.tutorvista.com/search

www.newencyclopedia.com

www.springer.com/materials

www.yourdiscovery.com

Abadi Ilmu Sdn. Bhd., Integrated Curriculum ForSecondary Schools, Chemistry

Form 4, by Low Swee Neo, Lim Yean Ching, Eng Nguan Hong, Lim Eng Wah and

Umi Kalthom binti Ahmad

Oxford FajarSdn. Bhd., SUCCESSChemistry SPM by Tan Yin Toon, Loh Wai

Leng, Tan On Tin

37662871 Chemistry Form 4 Manufactured Substances in Industries

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