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MANUFACTURED SUBSTANCES IN INDUSTRY

1. The composition , properties and uses of some alloy

Alloy Composition Properties Uses Bronze Cu

Tin -Hard and strong -does not corrode easily -has shiny surface

-in building of statue or monuments. -in making of medals -swords and artistic material

Brass Cu Zinc

-harder than copper -in making of musical instruments and kitchenware

Steel Iron Carbon

Hard and strong -in construction of buildings and bridges -in building of the body of cars and railway tracks

Stainless steel

Iron Carbon Chromium

-shiny -strong -does not rust

-in making of cutlery -in making of surgical instrument

Duralumin Aluminium Copper Magnesium manganese

-light -strong

-in building of the body of aeroplane and bullet trains

Pewter Tin, Copper antimony

-lustre, shiny -strong

In making of sourvenirs

Paper 3 1. The copper wire in an electric cable can be easily bent by hand. A one-cent coin made an alloy of copper with tin and zinc cannot be bent easily. Referring to situation above, plan a laboratory experiment to investigate the effect of alloy formation on the hardness of a metal. Statement of problem Does the formation of alloy increase the hardness of a metal? Hypothesis Bronze is harder than copper Variable Manipulated: Metal block (copper) and its alloys Responding: Size of the dent (made by the metal ball on the block) Constant variable: mass of the weight / the height of the thread / type of metal of the ball List of apparatus Metal block, alloy block, steel ball bearing, weight, ruler, rope, retort stand

Copper atom

Stanum atom

Zinc atom

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Procedure: 1. Put the steel ball bearing on the metal block / copper 2. Pull the rope that tied to the weight until the weight is 60 cm high on the metal block / copper 3. Drop the weight onto the steel ball bearing 4. Measure the diameter of the dent made on the metal block and records it 5. Repeat the activity 3/5 times 6. Repeat step 1 to 5 by using the alloy block, replacing the metal block. Tabulation of data

Diameter of the dent (cm) Name of metal 1 2 3 4 5

Average , cm

Metal/ copper Alloy / bronze

Paper 2 Conclusion: the diameter of the dent on the copper metal is bigger Reason:

1. The presence of atoms of other metals / tin that are different sizes 2. Disturb the orderly arrangement of copper atoms 3. Tin atoms reduce the layers of copper atoms from sliding 4. Alloy is stronger and harder than pure metal.

2. You have learnt the steel is an alloy of iron. Steel is harder than pure iron. Both iron and steel can rust when exposed to air and water. Do they rust at the same rate? To compare the rate of rusting between iron, steel and stainless steel Problem Statement How does the rate of rusting between iron, steel and stainless steel differ Hypothesis Iron rust faster than steel and steel rust faster than stainless steel. Variables Manipulated : Iron, steel and stainless steel. Responding : intensity / amount of dark blue colour / rate of rusting Fixed : size of nail, concentration of solution, duration of rusting Procedure: 1. Clean the nails with sand paper (to removed the rust from all the nails) 2. Place the iron nail, steel nail and stainless steel nail into the test tube A, B and C respectively. 3. Prepare a 5 % jelly solution by adding 5 g jelly to 100 cm3 of boiling water. Add a few drop of potassium hexacyanoferrate (III) solution. 4. Pour the hot jelly into the test tubes until all the nails are fully immersed. 5. Leave the nails for 3 days. 6. Observe and record the intensity of the dark blue colour.

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Tabulation of data

Test tube The intensity of the dark blue colour A B C

Conclusion 1. The concentration of Fe2+ ions in the test tube A is higher than in test tube B. No Fe2+ ions are present in test tube C. 2. The rate of rusting in test tube A is higher than that in test tube B. No rusting takes place in test tube C. Alloy slow down the rate of rusting. Describe how toxic waste product from factory affects the quality of the environment. Your description should include the following aspects. Source, process and effect. Sample answer:

1. [Source] sulphur dioxide gas produced by factory or burning of fossil fuels 2. [process ] sulphur dioxide gas dissolves in rain water / water to form acid rain,

SO2 + H2O H2SO3] 3. [effect ] toxic waste / acid flows to into lakes and rivers, acid rain lowers the pH value of

water, soil and air. 4. fish and other aquatic organisms die. 5. acid rain corrodes concrete buildings and metal structures 6. acid destroys trees in forest 7. acid rain reacts with minerals in soil to produces salt which are leached out the top soil. 8. plants die of malnutrition and diseases. 9. soil becomes acidic, unsuitable for growth of plants and destroys the roots of plants. 10. sulphur dioxide causes respiratory problems in humans.

Properties, composition and uses different type of glass Type Properties Chemical

composition Uses

Fused glass -Very high softening point -Highly heat resistant -Does not crack when temperature changes -very resistant to chemical reactions -difficult to be shaped

SiO2 Lenses, telescope mirrors, optical fibres.

Soda lime glass

-low softening point -does not withstand heating -break easily -less resistant to chemical reactions -easy to be shaped - cracks easily with sudden change in temperature

SiO2 CaCO3 / Na2CO3

Flat glass, light bulb, mirrors, glass containers.

Borosilicate -lower thermal coefficient SiO2 Laboratory

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-heat resistant - Does not crack when temperature changes -very resistant to chemical reactions -does not break easily

B2O3 Na2O

glassware, cooking utensils. Automobile headlights.

Lead glass -low softening point -high density -High refractive index

SiO2 PbO CaO

Decorative items, crystal glass ware, lens, prism, chandelier

Composite Materials is a structural material that is formed by combining two or more different substances such as metal, alloys, glass, ceramics and polymers.

Composite material

Component Properties of component

Properties of composite

Uses of components

Concrete Hard but brittle, low tensile strength

Reinforced concrete

Steel Hard with high tensile strength but expensive and can corrode.

Stronger, high tensile strength does not corrode easily, can withstand higher applied forces and loads, cheaper.

Construction of framework for highway, bridges and high-rise building

Super-conductor

Copper(II)oxide, barium oxide

Insulators of electricity

Conducts electricity

Generators, transformers, electric cable, amplifiers, computer parts MRI

Glass of low refractive index

Fibre optics

Glass of high refractive index

Transparent, does reflect light rays.

reflect light rays and allow light rays to travel along the the fibre

Transmit data in the form of light in telecommunications

Fibre glass Glass Heavy, strong but brittle and non-flexible

Polyester plastic Light, flexible, elastic but weak and inflammable

Light, strong, tough, resilient and flexible wit high tensile strength not inflammable, low density, easily coloured, shaped and moulded.

Water storage tanks, small boat, helmet

Photo-chromic glass

Glass Transparent, does reflect light rays.

Silver chloride or silver bromide

Sensitive to light

Sensitive to light : darkens when light intensity is high, becomes clear when light intensity is low.

Photochromic optical lens, camera lens, car windshields, optical switches, light intensity meters.