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EVALUATION

Cloze Activity

Read the paragraph below and fill in the missing words.

The is about 30m high. It is made of and the inner side is lined with bricks made from . The fire bricks conserve in order to maintain the optimum needed for the reduction of iron III oxide.

In the blast furnace three important reactions take place.

At the bottom of the furnace, coke (carbon) is oxidised to . The reaction raises temperature of the furnace to 1600 degrees celcious since it is .

In the middle part of the furnace, carbon IV oxide is reduced by coke to Carbon II Oxide and the temperature drops to about 1000 degrees celcious since the reaction is endothermic. 

At the upper of the furnace where the temperature has fallen to about 700 degrees celcious iron (III) oxide is reduced to iron metal.

Both Carbon and Carbon (II) Oxide act as reducing agents, but is the main reducing agent because of the large surface that is in contact with the Iron (III) Oxide. The Carbon IV Oxide produced is recycled. The limestone fed into the furnace alongside coke and iron III Oxide is decomposed by heat in the furnace to form and Carbon (IV) Oxide.

Calcium Oxide being basic reacts with acidic and amphoteric oxide in the furnace to form .

The iron obtained from the blast furnace is 90-95% pure and is called "pig iron".

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Case Study

The extraction of Iron from its ores takes place in the blast furnace. Below is a simplified diagram of a blast furnace. Study it and answer the questions that follow.

a) Name: 

i) One of the substances in the slag.                                                                                         (1mk)

ii) Another iron ore material used in the blast furnace.                                                         (1mk)

iii) One gas which is recycled.                                                                                                     (1mk)

b) Describe the processes which lead to the formation of Iron in the blast furnace.       (3mks)

c) State the purpose of limestone in the blast furnace.                                                           (1mk)

d) Give a reason why the melting point of iron obtained from the blast furnace is 1200 degrees celcious while that of pure iron is 1535 degrees celcious.                                     (2mks)

e) State two uses of steel.                                                                                                            (2mks)