Question

9 gm of $Al$ (at. Wt. = 27) will react completely with an acid to give :

• A. one mole of $H_2$
• B. one half mole of $H_2$
• C. one-third mole of $H_2$
• D. none of these

Answer 1

Answer: (B)

one half mole of $H_2$

$Al$ will react with acid (HCl) to produce $AlC{l}_3$.

$2Al+6HCl\to 2AlC{l}_3+3H_2$

One mole of $Al$ reacts with 3 moles of acid to produce 1.5 moles of $H_2$.

$\frac{1}{3}$ mole of $Al$ reacts with 1 mole of acid to produce 0.5 mole of $H_2$.