Extraction of Metals - Result Question 84
####87. Give briefly the isolation of magnesium from sea water by the Dow’s process.
Give equations for the steps involved.
$(1993,3 M)$
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Solution:
- Sea water (contain $\left.MgCl _2\right)+Ca(OH) _2$
$$ \longrightarrow Mg(OH) _2 \downarrow+CaCl _2(a q) $$
(i) $Mg(OH) _2+2 HCl \longrightarrow MgCl _2+2 H _2 O$
$$ \xrightarrow[\text { Dryness }]{\text { Heat to }} MgCl _2(s) $$
(ii) $MgCl _2(s) \xrightarrow[NaCl]{\text { Fusion }} Mg^{2+}+2 Cl^{-} \xrightarrow{\text { electrolysis }} Mg$
(At cathode)
