Question

Look at the following reaction:
$LiH+Al{H}_3⟶LiAl{H}_4$

Here $Al{H}_3$ and $LiH$ act as:

• A. Lewis acid and Lewis base
• B. Lewis base and Lewis acid
• C. Bronsted base and Bronsted acid
• D. None of these

Answer 1

The correct option is A

Lewis acid and Lewis base

As shown in the figure, the central metal atom in $Al{H}_3$ has only six valence electrons. Hence, it could accept a pair of electrons (Lewis acid) to complete its octet. On the other hand, $H^{-}$ is a Lewis base because it has two valence electrons thus having a completely filled shell. Further, since the ion readily shares or donates electrons - it acts as a Lewis base.