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(a) Give the name and formula of the main orea of iron and zinc.(b) How is the main ore of aluminium concentrated?(c) Why ‘the food containing iron salts’ should not be cooked in aluminium utensils? |
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Answer» (a) The main ores of iron and zinc are:
(b) Conversion of Impure Bauxite to Sodium aluminate Al2O3.2H2O + 2NaOH +150°C - 200°C → 2NaAlO2 + 3H2O Impurities such as Fe2O3 and SiO2 remain unaffected with conc.NaOH. Conversion of Sodium aluminate to Aluminium hydroxide. NaAlO2 + 2H2O +50°C - 60°C → NaOH + Al(OH)3 Conversion of Al(OH)3 to pure Alumina. 2Al(OH)3 +1100°C → Al2O3 + 3H2O (c) A layer of aluminium is formed on iron at high temperature during cooking and food becomes deficient in iron. |
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