Question

Which of the following chemicals does not liberate hydrogen gas on reaction with aluminium metal?

• A. Dil sulphuric acid
• B. Aqueous sodium hydroxide
• C. Dil hydrochloric acid
• D. Conc. nitric acid

Answer 1

Answer: (D)

Dilute and concentrated $HN{O}_3$ has no effect on Al, Aluminium is rendered passive by nitric acid due to the fopnation of a thin. film of oxide $\left(A{l}_2{O}_3\right)$ on its surface.
Aluminium dissolves in dil. $HCl$ and liberates dihydrogen. $2A{l}_{(S)}+6HC{l}_{(aq)}⟶2A{l}_{(aq)}^{3+}+6Cl-{}_{(aq)}+3H_{2(g)}$
Aluminium also reacts with aqueous alkali and liberates dihydrogen.
$2A{l}_{(S)}+2NaO{H}_{(aq)}+6H_2{O}_{(l)}⟶2Na{\left[Al(OH{)}_4\right]}_{(aq)}+3H_{2(g)}$
$2Al+6HN{O}_{3(conc)}⟶A{l}_2{O}_3+6N{O}_2+3H_{2}O$
$2Al+6H_{2}S{O}_4⟶A{l}_2{\left(S{O}_4\right)}_3+3S{O}_2+6H_{2}O$