Give briefly the isolation of magnesium from sea water. Give equations for the steps involved.

Explanation

In sea water, `MaCl` is present.
`MgCl_(2) + Ca(OH)_(2) rarr Mg(OH)_(2) darr + CaCl_(2)`
`underset ("Dry")(Mg(OH)_(2)) overset (Delta) rarr MgO + H_(2)O`
`MgO + C + Cl_(2) overset (Delta) rarr MgCl_(2) + CO uarr`
The anhydrous magnesium chloride is fused `NaCl` and anhydrous calcium chloride. The mixture is electrolysed at `700^@ C` in the presence of an inert gas in an electrolytic cell. Magnesium is discharged at the cathode. The purpose of the addition of `NaCl` and `CaCl_(2)` to anhydrous `MgCl_(2)` is to lower the fusion temperature and make fused mass a good conductor of electricity. Sodium chloride prevents the hydrolysis of magnesium chloride.
`{:("At anode":,2Cl^(Ө)rarr Cl_(2) + 2e,,,),("At cathode":,Mg^(2+) + 2e^(Ө) rarr Mg,,,):}`.