SS3 First Term Chemistry Lesson Note – Iron and Aluminum

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WEEK 7

TOPIC: IRON AND ALUMINUM

CONTENT:

1. Extraction
2. Types and uses
3. Rusting of iron and methods of prevention iron
4. Aluminium-extraction, properties and uses

Iron is a 3-d, block metal and transition element with atomic number 26. It has the symbol F_e with electronic configuration of 2, 8,14, 2 Iron is the second most abundant metal found in the earth crust. It is often found as iron ore. Examples include haematite (F₂O₄) the commonness magnetite (F_e O₄), pyrites (F_e S₃), spathic or siderite iron ore (Fe CO₃), limonite (FeO₃. H₂O). It is present as trioxosilicates (iv) in clay soils. It is found in animal haemoglobin and plant chlorophyll. It can be found in Nigeria Anambra, Kogi and Edo state.

PERIOD  1: EXTRACTION

Iron ore is first roasted in air in a steel blast furnace so that iron (III) oxide is produced. The iron (III) oxide is then mixed with coke and limestone and heated to a very high temperature in the furnace. The ingredients are loaded into the furnace from the top while a blast of hot air is introduced from the bottom to the top through small pipes. The temperature inside the furnace varies from about 2000⁰C near the bottom to about 200⁰C at the top.

1. The oxygen in the hot air moving up oxides the hot coke coming down to Carbon (iv) oxide

C_(s)  + O_2(g)  → CO_2(g)

2. The CO_2(g) is forced up to meet more hot coke which reduces it to carbon (II) oxide.

CO_2(g)  + C_(s)   → 2CO_(g)

3. The CO then reacts with Fe₂O₃, reducing it to Fe

Fe₂O_3(g) + 3CO_(g) →  2Fe_(l) + 3CO_2(g)

The molten iron formed sinks to the bottom of the furnace, and is tapped off. The limestone present decomposes at high temperature to yield calcium oxide, which then combines with the silicon (iv) oxide (impurity) to form calcium trioxosilicated (iv)                                       

PERIOD 2: TYPES AND USES

1. Pig Iron: It is obtained direct the blast furnace and is quite impure. It contains 5% of carbon together with impurities like phosphorus, silicon etc. The presence of impurities lowers the melting point from 1530⁰C to about 1200⁰C. Dig iron is hard and brittle and can be used for industrial purposes.

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