# What is the type of the reaction 4Al + 6HCl -> 2Al_2Cl_3 + 3H_2?

May 27, 2018

This is a redox process....note that $A {l}_{2} C {l}_{3}$ is a typo...

#### Explanation:

Aluminum metal is oxidized to aluminum ion...

$A l \left(s\right) \rightarrow A {l}^{3 +} + 3 {e}^{-}$ $\left(i\right)$

Hydrogen ion is REDUCED to dihydrogen...

${H}^{+} + {e}^{-} \rightarrow \frac{1}{2} {H}_{2} \left(g\right)$ $\left(i i\right)$

We add $\left(i\right) + 3 \times \left(i i\right)$

$A l \left(s\right) + 3 {H}^{+} + 3 {e}^{-} \rightarrow A {l}^{3 +} + \frac{3}{2} {H}_{2} \left(g\right) + 3 {e}^{-}$

...on cancellation....

$A l \left(s\right) + 3 {H}^{+} \rightarrow A {l}^{3 +} + \frac{3}{2} {H}_{2} \left(g\right)$

Of course we could add $3 \times C {l}^{-}$ to both sides...

$A l \left(s\right) + 3 H C l \left(a q\right) \rightarrow A l C {l}_{3} \left(a q\right) + \frac{3}{2} {H}_{2} \left(g\right)$