Question

Metallic magnesium is prepared by:

• A. Reduction of MgO by coke
• B. Electrolysis of aqueous solution of $Mg{\left(N{O}_3\right)}_2$
• C. Displacement of Mg by iron from $MgS{O}_4$ solution
• D. Electrolysis of molten $MgC{l}_2$

Answer 1

The correct option is D Electrolysis of molten $MgC{l}_2$

Reaction:

$M{g}^{2+}+Ca(OH{)}_2\to Mg(OH{)}_2+CaC{l}_2\stackrel{dil.HCl}{\to }MgC{l}_2.6H_{2}O$

$MgC{l}_2.6H_{2}O\to MgC{l}_2.2H_{2}O\stackrel{dryHCl}{\to }MgC{l}_2$

Magnesium chloride obtained by any of the above methods is fused and mixed with sodium chloride and calcium chloride in the temperature range of $973-1023K$. The molten mixture is electrolysed. Magnesium is liberated at the cathode and chlorine is evolved at graphite anode.