Question

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

Answer 1

This is a redox process....note that `Al_2Cl_3` is a typo...

Explanation:

Aluminum metal is oxidized to aluminum ion...

`Al(s) rarr Al^(3+) +3e^-` `(i)`

Hydrogen ion is REDUCED to dihydrogen...

`H^+ +e^(-) rarr 1/2H_2(g)` `(ii)`

We add `(i)+3xx(ii)`

`Al(s)+3H^+ +3e^(-) rarr Al^(3+) +3/2H_2(g)+3e^-`

...on cancellation....

`Al(s)+3H^+ rarr Al^(3+) +3/2H_2(g)`

Of course we could add `3xxCl^-` to both sides...

`Al(s)+3HCl(aq) rarr AlCl_3(aq) +3/2H_2(g)`