Chemistry Form 4 Chapter 9

CHAPTER 9 : MANUFACTURED SUBSTANCES IN INDUSTRY

NAME: ABDUL NAJIB BIN ABDUL AZIZ CLASS: 4 KM3 SCHOOL: TAMAN POLO

CONTENT

Content

Page

Introduction 9.1 Sulphuric acid 9.1.1 Properties of sulphuric acid 9.1.2 The uses of sulphuric acid 9.1.3 The industrial process in manufacture of sulphuric acid 9.1.4 Environmental pollution by sulphuric acid 9.2 Ammonia and its salt 9.2.1 Properties of ammonia 9.2.2 The uses of ammonia 9.2.3 The industrial process in manufacture of ammonia 9.3 Alloys 9.3.1 Physical properties of pure metals 9.3.2 Meaning and purpose of making alloys 9.4 Synthetic polymers 9.4.1 The meaning and types of polymers 9.4.2 Advantages of synthetic polymers 9.4.3 Environmental pollution caused by synthetic polymers 9.4.4 Methods to overcome the environmental pollution caused by synthetic polymers 9.5 Glass and ceramics 9.6 Composite material Conclusion References

3 4 5 9 12 13 16 17 18 20 21 23 23 23 24 28 30 31

INTRODUCTION All the objects that exist around us are made up of chemical substances. These objects exist an element, compound or mixture. All these objects contribute benefit to humankind. As time goes on, human has done many researches to ensure all these chemical substances will be enough for the use of themselves. Chapter 9 of Form 4 syllabus introduces the students with manufactured substances in industry. This is important for the students to appreciate the knowledge of 2

chemistry that is still new for themselves. Personally, I think that this chapter is an interesting chapter as it revealed the way of scientist produces the material around me. It also gives me new knowledges of the uses of chemical substances that I usually found in the laboratories. I hope, by learning this chapter, I will be more interested in learning chemistry as it will help me in the future. All the equations from this chapter make me more understand of the previous chapters.

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.

Figure 9.1 A molecule of sulphuric acid.

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. 3

6. Concentrated sulphuric acid is a viscous colourless liquid.

Soluble in

Non-volatile acid

Diprotic acid

Properties of sulphuric acid Highly corrosive

Dense

Oily liquid

Viscous colourless liquid

Figure 9.2 Properties of sulphuric acid

9.1.2 The uses of sulphuric acid 1) To manufacture fertilizers There are many fertilizers that can be made of sulphuric acid. Some of them are: a) Calcium dihydrogen phosphate (superphosphate) 2 24 + Ca 3(PO4) 2 → Ca(H2 PO4) 2 + 2CaSO4 sulphuric acid + tricalcium phosphate → calcium dihydrogen phosphate 4

b) Ammonium sulphate 24

+2NH3 → (NH4) 2 SO4 sulphuric acid + aqueous ammonia → ammonium sulphate

c) Potassium sulphate

24

+2NH3 → (NH4) 2 SO4 sulphuric acid + aqueous ammonia → ammonium sulphate

1) 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 2) 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. 3) To manufacture paint pigments 5

The white pigment in paint is usually barium sulphate, BaSO4. The neutralization of sulphuric acid and barium hydroxide produces barium sulphate. 4) As an electrolyte in lead-acid accumulators 5) To remove metal oxides from metal surfaces before electroplating 6) To manufacture pesticides 7) The uses of sulphuric acid in school laboratories are: a.

As a strong acid

b.

As a drying or dehydrating agent

c.

As an oxidizing agent

d.

As a sulphonating agent

e.

As a catalyst

pesticides Remove metal oxides from metal surfaces beforeManufacture electroplating As an electrolyte in lead-acid accumulators

6

Manufacture fertilizers

Uses of sulphuric acid

Manufacture detergents

Manufacture paint pigments

Manufacture synthetic fibres

Figure 9.3 Uses of sulphuric acid

Synthetic fibres 9% As an electrolyte 10%

Metal cleaning 2% Dyes 2% As an acid 2% Fertilisers 32%

Detergents 12% Paint pigment 15%

Other chemicals 16%

7

Figure 9.4 Uses of sulphuric acid in industry

9.1.2 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 water via the contact process. 3. The Contact process involves three stages.

Sulphur

→ Sulphur dioxide → Sulphur trioxide → I

II

Sulphuric acid

III

4. Stage I: Production of sulphur dioxide gas, SO2. This can be done by two methods,

8

a)

Burning of sulphur in dry air. + →

b)

Burning of metal sulphide such as zinc sulphide in dry air. 2ZnS + 3 → 2 + 2ZnO

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 as a catalyst.

b)

A temperature of between 450°C to 550°C.

c)

A pressure of one atmosphere 2 SO2 + O2 →

6. Stage III: Production of sulphuric acid a) Sulphur trioxide is dissolved in concentrated sulphuric acid, H2SO4 to produce oleum, H2S2O7 H2SO4+ SO3 → H2S2O7 b) Oleum is reacted with water to form concentrated H2SO4.

H2S2O7+ H2O → 2 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

9

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

Sulphur or metal sulphide burned in air

Sulphur dioxide, a) the presence of a vanadium(V) oxide as a catalyst. b) a temperature of between 450°C to 550°C. c) a pressure of one atmosphere , SO3 dissolved in sulphuric acid, H2SO4

, H2S2O7

10

diluted with equal volume of water H2O

Concentrated sulphuric acid H2SO4

Figure 9.5 Flowchart of Contact process

9.1.3 Environmental pollution by sulphuric acid

1.

Sulphur dioxide is the main byproduct produced when sulfur-containing fuels such as coal or oil are burned.

2.

Sulphuric acid is formed by atmospheric oxidation of sulphur dioxide in the presence of water. It also produces sulphurous acid.

3.

Sulphuric acid and sulphurous acid are constituents of acid rain.

4.

Acid rain can cause many effects such as: i. Corrodes concrete buildings and metal structure ii. Destroys trees and plants iii. Decrease the pH of th 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

11

ii. Remove sulphur dioxide from waste air by treating it with calcium carbonated before it is released

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.

Figure 9.6 A molecule of ammonia.

5. It is about one half as dense as air 6. It reacts with hydrogen chloride gas to produce white fumes of ammonium chloride. NH3 + → 7. Ammonia is alkaline in property and reacts with dilute acids in neutralization to produce salts. For examples: NH3 + N 3 → NH4N 3 2NH3 + 24 → (NH4) 2 SO4

12

1. Aqueous solutions of ammonia produces OH − ions (except Na+ ion, K+ ion, and Ca 2+ ion) forming metal hydroxides precipitate.

Fe 3+ + 3 − → Fe(H) 3 Brownprecipitate

Mg 2+ + 2 − → Mg(H) 2 Whiteprecipitate

2. Some metal hydroxides such as zinc hydroxide and copper (II) hydroxide dissolves in excess aqueous ammonia to form complexes.

Zn(OH)2 + 4NH3→ [Zn(NH3)4] 2+ + 2 − Cu(OH)2 + 4NH3→ [Cu(NH3)4] 2+ + 2 −

13

Extremely Properties solubleof inammonia water Colorless Pungent Weak alkali smell

14

Figure 9.7 Properties of ammonia

9.2.2 The uses of ammonia 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:

Mass of nitrogen X 100%

Molar mass of

15

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) C + H2O → CO + H2

b) The reaction between steam and natural gas ( consisting mainly of methane)

CH4 + 2H2O → CO2 + 4H2 5. In the Haber process: 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. 16

b) The gas mixture is passed through a catalyst of powdered iron at a temperature of 450 - 550°C. c) At this optimum temperature and pressure, ammonia gas is produced. N2+ 3H2 → 2NH3

9.3 ALLOYS 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 atoms enables 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. 17

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.

High Goodmelting conductor Ductile High and of boiling density electricity point Properties of Malleable metals

Figure 9.8 Properties of metals 18

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. 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

19

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 1. A polymer is a very big molecule (macromolecule). Hence, the relative molecular mass of a polymer is large. 2. The properties of polymer are different from its monomers. 3. Polymers can be divided into two types: a) Naturally occurring polymers 1. This type of polymer exists in living things in nature like the plants and animals. 2. Examples of naturally occuring polymers are: a) Protein 20

b) Carbohydrate c) Natural rubber 3. Naturally occuring polymers are formed by the joining of monomers by polymerization. 4. Protein is formed by the joining of monomers known as amino acid. 5. Carbohydrate is formed by the joining of monomers known as glucose. 6. Natural rubber is formed by the joining of monomers known as isoprene. a) Synthetic polymers 1. This type of polymer are man-made by chemical process in the laboratories. 2. The raw material for synthetic polymers are obtained frompetroleum. 3. 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.

21

9.4.2 Advantages of synthetic polymers a) Strong and light b) Cheap c) Able to resist corrosion d) Inert to chemical reactions e) Easily moulded or shaped and be coloured f) 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

22

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 1. Differences between glass and cerement are, glass is transparent, while ceramic is opaque. Ceramic can withstand a higher temperature than normal glass. 2. 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 •

It can withstand high temperature

d) Lead glass 23

•

High refractive index

1. 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 Fused glass

Properties Very high softening point (1700 °C) hence, highly heat

Chemical composition SiO2 (99%) Ba2 O 3 (1%)

Examples of uses Telescope mirrors, Lenses Optical fibres

resistant

Laboratory glass

Transparent to

wares

ultraviolet and infrared light Difficult to be made into different shapes Does not crack when temperature changes (very low thermal 24

expansion coefficient) Very resistant to chemical reactions Low softening point (700 °C), hence, does not withstand heating Breaks easily

Bottles

Cracks easily with

Soda lime glass

sudden temperature

SiO2 (70%)

Windowpanes

changes (high

Na2O (15%)

Light bulbs

coefficient of

CaO

Mirrors

expansion)

Others (5%)

(3%)

Bowls ( The most widely

Less resistant to

used type of glass)

chemical reactions Easy to be made into different shapes

High softening point (800°C). Thus it is heat resistant Does not crack easily with sudden Borosilicate glass

temperature changes Transparent to

SiO2 (80%) Ba2 O 3 (15%) Na2O (3%) Al 2 O 3

ultraviolet light

Laboratory apparatus Cooking utensils Electrical tubes Glass pipelines

More resistant to chemical reactions Does not break easily Lead crystal glass

Low softening point

SiO2 (55%)

Decorative items

(600 °C)

PbO( 30%)

Crystal glass25

High density

K2O (10%)

wares

High refractive index

Na2O ( 3%)

Lens

Reflects light rays

Al2 O 3 ( 2%)

Prisms

and appears spar

Chandeliers

kling

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 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.

26

Composite material

Reinforced concrete

Component

Properties of

Properties of

Concrete

component Hard but brittle,

composite Stronger, higher

With low tensile

tensile strength, not

strength Hard with high

so brittle, does not

Steel

tensile strength but expensive and can corrode Glass of low

Transparent, does

corrode easily, can withstand higher applied forces and loads, relatively cheaper Reflect light rays 27

refractive index

not reflect light

and allow light rays

rays. Heavy, strong but

to travel along the

Glass of high refractive index

brittle and non-

Glass

flexible Heavy, strong but

Light, strong, tough,

brittle and non-

resilient and

flexible Light, flexible,

flexible, with high

Fibre optics

Fibreglass Polyester plastic

elastic but weak and

Photochromic glass

Glass

inflammable Transparent and not

Silver chloride, or

sensitive to light Sensitive to light

silver bromide

fibre

tensile strength and not flammable Sensitive to light: darkness when light intensity is high, becomes clear when light intensity is low

Figure 9.9 Composite material and their new properties

CONCLUSION We must appreciate these various synthetic industrial materials. One of the way is by doing continuous research and development ( R & D ) to produce better materials used to improve our standard of living. As we live in a changing world, our society is getting more complex. New materials are required to overcome new challenges and problems we face in our daily lives. Synthetic material are developed constantly due to the limitation and shortage of natural materials. 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 28

problem will stimulate the development of new synthetic materials. For example, the new use of plastic composite material will replace metal in the making of a stronger and lighter car body. This will save fuel and improve speed. Plastic composite materials may one day used to make organs for organ transplant in human bodies. This will become necessity with the shortage of human organ donors. 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. A responsible and systemic method of handling the waste of synthetic materials and their by-product is important to prevent environmental pollution. The recycling and development of environmental friendly synthetic material should be enforced.

REFERENCES 1. Tan Yin Toon, Loh Wai Leng, Tan On Tin, 2008, SUCCESS Chemistry SPM, Oxford Fajar Sdn.Bhd. 2. Website http://www.answers.com

29