p-Block Elements-I - Result Question 55
####26. (i) How is boron obtained from borax? Give chemical equations with reaction conditions.
(ii) Write the structure of $B _2 H _6$ and its reaction with $HCl$.
(2002)
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Solution:
- (i) $Na _2 B _4 O _7+HCl \longrightarrow NaCl+H _3 BO _3$
$$ \begin{gathered} H _3 BO _3+HCl \stackrel{\Delta}{\longrightarrow} BCl _3+H _2 O \ BCl _3+Al \stackrel{\Delta}{\longrightarrow} B+AlCl _3 \end{gathered} $$
(ii) $B _2 H _6$ :
It has 4 terminal $B-H$ bonds. There are two $B-H-B$, three centred two electron bridged bonds.
$B _2 H _6+HCl \longrightarrow B _2 H _5 Cl+H _2$
