Paper 1 May/June 2021 CHEMISTRY (9701/11) IGCSE
$LiAl{\text{ }}{H_4}$ contains $AlH_4^ - $ ions in which aluminium has an oxidation state of +3.
$LiAl{\text{ }}{H_4}$ reacts with water, as shown.
$LiAl{\text{ }}{H_4} + 4{H_2}O \to 4{H_2} + LiOH + Al{\left( {OH} \right)_3}$
In this reaction, each of the four water molecules produces one hydroxide ion. It does this by losing
one ${H^ + }$ ion, which reacts with the $LiAl{\text{ }}{H_4}$.
Which changes in oxidation…