Question

Explain the method of extractioin of amorphous silicon using silica.

Answer 1

Amorphous silicon extraction process:

• Finely powdered silica is maxed with Mg powder and the mixture is heated in a fire clay crucible.
• The products obtained are magnesium oxide and silicon.
• The product is then washed with dilute HCl to dissolve magnesium oxide which is present as a basic impurity.
• Then, to remove the unreacted silica it is washed with hydrofluoric acid.
• The powder then left behind is silicon in its amorphous form.
• $Si{O}_2+2Mg\to Si+2MgO$