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Dow's process f extraction of Mg involve...

Dow's process f extraction of Mg involves extraction of Mg from sea water. Sea water is concentrated is sun light and is then treated with milk of lime. Magnesium hydroxide obatained is reacted with dilute HCl and `MgCl_(2)` thus obtained is crystallised. The molten mixture containing angydrous 35% `MgCl_(2),` 50% NaCl and 15% `CaCl_(2)` is electrolysed when magnesium is discharged at cathode. NaCl and `CaC_(2)` are added to lower the fusion temperature and to increase to the conductance. Mg electrolysed is protected from atmospheric oxidation by a blanket of inert gases.
Molten mixture of NaCl and `CaCl_(2)` is added to hte molten `MgCl_(2)` beacuse:

A

it increase the melting point of `MgCl_(2)`.

B

`CaCl_(2)` acts as a dehydrating agent.

C

`CaCl+NaCl` lower the melting point of `MgCl_(2)`.

D

none of these

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The correct Answer is:
c
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Dow's process of extraction of Mg involves extraction of Mg from sea water. Sea water is concentrated in sun-light and is then treated with slaked lime. Magnesium hydroxide is heated in a stream of HCl to give MgCl_(2) which is electrolysed to discharge Mg. The mixture is in the ratio 35% MgCl_(2)+50% NaCl+15% CaCl_(2) . NaCl and CaCl_(2) are added to lower the fusion temperature and to increases the conductance. Mg^(2+) +Ca(OH)_(2) to Mg(OH)_(2)+Ca^(2+) Mg(OH)_(2)+2HCl to MgCl_(2)+2H_(2)O(l) Electrolysis of fused MgCl_(2) hArr Mg^(2+)+2Cl Mg^(2+)+2e^(-) to Mg ( At Cathode) 2Cl^(-) to Cl_(2)+2e^(-) (At Anode) Mg electrolysed is protected from atmospheric oxidation by a blanket of inert gases. In the hydrated chloride of Mg the value of x is :

Dow's process of extraction of Mg involves extraction of Mg from sea water. Sea water is concentrated in sun-light and is then treated with slaked lime. Magnesium hydroxide is heated in a stream of HCl to give MgCl_(2) which is electrolysed to discharge Mg. The mixture is in the ratio 35% MgCl_(2)+50% NaCl+15% CaCl_(2) . NaCl and CaCl_(2) are added to lower the fusion temperature and to increases the conductance. Mg^(2+) +Ca(OH)_(2) to Mg(OH)_(2)+Ca^(2+) Mg(OH)_(2)+2HCl to MgCl_(2)+2H_(2)O(l) Electrolysis of fused MgCl_(2) hArr Mg^(2+)+2Cl Mg^(2+)+2e^(-) to Mg ( At Cathode) 2Cl^(-) to Cl_(2)+2e^(-) (At Anode) Mg electrolysed is protected from atmospheric oxidation by a blanket of inert gases. Molten mixture contains Mg^(2+), Na^(+) and Ca^(2+) but at cathode only Mg^(2+) is discharged because :