manufactured substances in industry. a) sulphur dioxide is produced from one of these reaction : i)...

MANUFACTURED SUBSTANCES IN INDUSTRY

A) Sulphur dioxide is produced from one of these reaction :

i) Sulphur is burnt in air to produce sulphur dioxide :

S + O₂ SO₂ ii ) Lead (II) sulphide is roasted, also to

produce sulphur dioxide.

2PbS + 3O₂ 2SO₂ + 2PbO

b) Impurities such as water vapour and arsenic compound are removed to prevent poisoning of the catalyst

a) Sulphur dioxide is then mixed with

excess oxygen.

b) Sulphur dioxide is oxidised to sulpur trioxide :

2SO2 + O2

2SO2

STAGE II – FORMATION OF SULPHUR TRIOXIDE

A) Sulphur trioxide is dissolved in concentrated sulphuric acid to form oleum :

SO3 + H2SO4 H2S2O7 ( Oleum)

B) The oleum produced is then diluted with water to produced concentrated sulphuric acid :

H2SO4 + H2O 2H2SO4

STAGE III – FORMATION OF SULPHURIC ACID

However, this is not done in industry to produce sulphuric acid… Explain

- Because SO2 has low solubility in water.

- SO2 react violently in water producing large amount of heat

3 USES OF SULPHURIC ACID:

Sulphur dioxide is released through burning of petrol in cars and also released through chimney of factories.

Wind carries the pollutants around the globe.

Sulphur dioxide causes respiratory problems in human.

The gas reacts with water to form acid rain. This acid rain corrodes buidings and metal structures

Acid rains destroy trees in forests.

Acid rains flows into lakes and rivers and caused fish and other aquatics organisms die.

SOIL POLLUTIONPH of the soil decrease.

Roots the soil are destroyed.

Plants die of malnutrition and diseases.

i) Use non-leaded petrol or low – sulphur petrol.

Use catalytic converters in motor vehicles to clean up emissions from car engines.

Use alternative sources of energy to replace fossil fuels; i.e steam, solar, wind, waves, biomass.

USES OF AMMONIA

i) To manufacture nitrogenous fertilizers such as ammonium nitrate and urea.

ii) To be converted into nitric acid and used for making explosive.

iii) To produce ammonium chloride ; used as an electrolyte in dry cells.

PROPERTIES FOR AMMONIAVERY

SOLUBLE IN

WATER

PUNGENT SMELL

COLOURLESS GAS

LESS DENSE THAN AIR

BURNS IN OXYGEN BUT NOT

IN AIR

ALKALINE

GIVES A WHITE FUMES WHEN

REACT WITH WATER

Ratio of hydrogen &nitrogen gas ?

1 mole N2 : 3 moles H2

3 conditions for manufacture ammonia :

Optimum temperature (450°C – 550°C)Optimum pressure ( 200-500 atm)Using iron as catalyst

Equation to form ammonia :Equation to form ammonia :

N2 + 3H2 2NH3

ALLOYS

i) Lusters means metals reflect light or have a shiny appearance.

ii) Ductility means metal can be pulled into wires.

Iii) Malleability is the property that allows metals to be hammered or rolled into thin sheets.

iv ) Conductivity means that heat or electrical charges move easily through the material. Metals and alloys have high conductivity because some of their electrons are not tightly held by by their atoms.

E) Alloy – a mixture of a metal with one or more other elements where the mixture retains the properties of the metal.

F) Alloys are produced to obtain a material with improved properties such as greater hardness, strength, lightness or durability

+

Pure metal APure metal B

ALLOY

force

force

Layers of atoms slide

Atoms are ductile

Atoms are malleable The shape of metal changes

force

Atoms in pure metals are of the same size

The atoms are also in orderly arragement

There are less empty spaces in between the atoms.

Therefore,when force applied, layer of atoms slide or slip easily

H)Why is cutlery made of stainless steel and not iron?

They do not corrode easily

I) Why is pure iron not used to make building materials ?

Pure iron rust and corrode easily.

ALLOYS

COMPOSITION OF ALLOYS & THEIR PROPERTIES

BRASS

STAINLESS STEEL

BRONZE

PEWTER

STEEL

DURALAMIN

Made up mostly copper and tin.Hard and strong , does not corrode easily and has shiny surfaces

Made up of copper and zinc, harder than copper

Made up of 93% Aluminium. Light and strong

COMPOSITION

ALLOYS

COMPOSITION OF ALLOYS & THEIR PROPERTIES

BRASS

STAINLESS STEEL

BRONZE

PEWTER

STEEL

DURALAMIN

Contains chromium ironand carbon.

Shiny, strong and does not rustMade up 96% tin copper and

antimony. Lustre, shiny and strong

Hard and strong

COMPOSITION

3 aims in making alloys :

A) To increase the hardness and strength of a metal.

B) To prevent corrosion of rusting.

C) To enhance the appearance of the metal surface.