Collect metal vessels and metal articles write the steps in procedure that can be done in the laboratory for giving glitter to this introduction
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Answer:
Aluminum is extracted electrolytically from bauxite, which is aluminum ore. Bauxite contains hydrated alumina (Al2 O3) with some proportions of iron oxide. The extraction process involves the following steps.
A. Purification of bauxite - This is a two-step process called Bayer's process:
First, we dissolve bauxite in aqueous sodium hydroxide (NaOH) by digestion. Bauxite with higher hydroxide contents (Al(OH)3) are treated at 120-140° C with dilute (3M) NaOH and bauxite with higher oxide content (AlOOH) is treated at a higher temperature (200-250° C) and a higher pressure (35 atm) with 5-7M NaOH.
Next, the insoluble impurities are separated by filtration. Al(OH)3 is precipitated by carbon dioxide and ignited to ~1200° C to obtain Al2 O3.
B. Purified bauxite is then dissolved in cryolite, which is 5-7% CaF2 , 5-7% AlF3, 2-8% Al2 O3 and electrolyzed at 950° C in a carbon-lined steel cathode with hard carbon rods as the anode. Li2 CO3 is used to (i) lower the melting point of the electrolyte, (ii) permit a larger current flow, and (iii) reduce fluorine emission.
The resulting reactions are produced:
Al2 O3 → 2Al3+ + 3O--
At cathode: 2 Al3++ 6e- → 2Al
At anode: 3O-- - 6e- → 3O