Question

What is an aqueous solution of aluminum chloride?

Answer 1

Hint : Aluminum chloride is a major compound of aluminum which is the third abundant element in earth’s crust after oxygen and silicon. Aluminum chloride is formed by passing chlorine gas on heated Al turning in the presence of oxygen. The vapors get condensed and form anhydrous aluminum chloride.

Complete Step By Step Answer:
Hydrated aluminum chloride is formed when HCl is treated with aluminum, aluminum hydroxide:
$2Al + 6HCl \to AlC{l_3} + 3{H_2} \\\ Al{(OH)_3} + 3HCl \to AlC{l_3} + 3{H_2}O$
Hydrated aluminum chloride: $AlC{l_3}{H_2}O$ during the reaction dilute hydrochloric acid go through the solution to obtain crystals of hydrated aluminum chloride.
Aqueous $AlC{l_3}$ is acidic in nature which happens due to hydrolysis of $AlC{l_3}$ .
$AlC{l_3} + 3{H_2}0 \to Al{(OH)_3} + 3HCl$
$Al{(OH)_3} + NaOH \to NaAl{O_2} + 2{H_2}O$
Hydrolysis of $AlC{l_3}$ forms a weak base and a strong acid.
$AlC{l_3} + 3NaOH \to Al{(OH)_3} + 3NaCl$
Reaction with ammonium hydroxide: A gelatinous precipitate of aluminum hydroxide is formed which does not dissolve even in excess of $N{H_4}OH$ .
Reaction with sodium hydroxide:
$AlC{l_3} + 3NaOH \to Al{(OH)_3} + 3NaCl$
$Al{(OH)_3} + NaOH \to NaAl{O_2} + 2{H_2}O$
On adding excess sodium hydroxide the gelatinous precipitate dissolves and forms sodium meta-aluminate.

Note :
It is used as a catalyst in many reactions and organic reactions. Aluminum chloride is an electron deficient molecule as aluminum in its outermost shell has three electrons which combine with three chlorine atoms to form covalent bonds. There is deficiency of two electrons, thus aluminum chloride also acts as Lewis acid as it has tendency to accept a lone pair. Hexahydrate $ AlC{l_3}{H_2}O\ ]is antiperspirant which helps to reduce excessive sweating