(a) Give the chemical names and formulae of main ores of (i) aluminium (ii) iron (iii) zinc.

(b) Which impurities are present in bauxite.

(c) What is red mud, how is it removed?

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Solution

(a) chemical names and formulae of main ores of (i) aluminium (ii) iron (iii) zinc

Ore Chemical name Formula
1. Bauxite Hydrated aluminium oxide $A l_{2} O_{3} .2 H_{2} O$
2. Cryolite Sodium aluminium fluoride $N a_{3} A l F_{6}$
3. Corundum Anhydrous aluminum oxide $A l_{2} O_{3}$

(b) Bauxite ore contains approximately 60% aluminium oxide. The rest being sand, ferric oxide and titanium oxide.

(c) Red mud consists of ferric oxide, sand etc. left after bauxite dissolves in NaOH forming sodium aluminate and is removed by filtration.

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Q. The following questions refer to the extraction of aluminium and iron from their ores:
(a) Name the principle ore from which (i) iron, and (ii) aluminium are extracted.
(b) What is the most important chemical process in the extraction of any metal? State how this essential step is carried out in the extraction of: (i) iron, (ii) aluminium.
(c) Iron and aluminium ores both, contain impurities. Explain, briefly how these impurities are removed in each case.
(d) What is the major impurity present in iron when it is removed from the furnace?
Name an alloy of zinc is used in simple voltaic cells.

Q. In the extraction of aluminium,
Process X: applied for red bauxite to remove iron oxide (chief impurity)
Process Y: applied for white bauxite to remove Z (chief impurity).

Then, Process X and impurity Z are:

Q. In the extraction of aluminium;
Process X: applied for red bauxite to remove iron oxide
Process Y: (Serpeck's process): applied for white bauxite to remove Z (chief impurity)

Then, process X and impurity Z are:

In order to obtain 1 tonner of aluminium, the following inputs are required. 4 tonnes of bauxite, 150 kg of sodium hydroxide and 600 kg of graphite. The aluminium compound in bauxite is aluminium oxide and the main impurity is Iron (III) oxide. Aluminium is obtained by the electrolysis of aluminium oxide dissolved in cryolite.

(a) When bauxite is treated with sodium hydroxide solution, what happens to:

(i) the aluminium oxide,

(ii) the iron (III) oxide?

(b) (i) Name the process used for the purification of bauxite.

(ii) Write the equation for the action of heat on aluminium hydroxide.

(ii) Write down the word which correctly completes the following sentence.By dissolving aluminium oxide in cryolite a ..........(conducting/non conducting) solution is produced.

(iii) Why is so much graphite required for the electrolytic process?

(iv) Write the equation for the reaction which takes palace at cathode.

Q. Answer the following questions:
(i) Name a metal which is found abundantly in the earth's crust.
(ii) What is the difference between calcination and roasting?
(iii) Name the process used for the enrichment of sulphide ore.
(iv) Write the chemical formulae of one main ore of iron and aluminium.
(v) Write the constituents of electrolyte for the extraction of aluminium.

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Ore	Chemical name	Formula
1. Bauxite	Hydrated aluminium oxide	$A l_{2} O_{3} .2 H_{2} O$
2. Cryolite	Sodium aluminium fluoride	$N a_{3} A l F_{6}$
3. Corundum	Anhydrous aluminum oxide	$A l_{2} O_{3}$

(a) Give the chemical names and formulae of main ores of (i) aluminium (ii) iron (iii) zinc. (b) Which impurities are present in bauxite. (c) What is red mud, how is it removed?

(a) Give the chemical names and formulae of main ores of (i) aluminium (ii) iron (iii) zinc.

(b) Which impurities are present in bauxite.

(c) What is red mud, how is it removed?