What are the products of the following reaction? 2Al(s) + 6H^+ (aq) ->2Al(s)+6H+(aq)

1 Answer
Jul 2, 2016

Aluminium cations and hydrogen gas.

Explanation:

You were given the reactants in the net ionic equation that describes the reaction between aluminium metal, "Al"Al, and hydrochloric acid, "HCl"HCl.

Hydrochloric acid is a strong acid, which means that it dissociates completely in aqueous solution to form hydrogen ions, "H"^(+)H+, which you'll very often see referred to hydronium cations, "H"_3"O"^(+)H3O+, and chloride anions, "Cl"^(-)Cl.

"HCl"_ ((aq)) -> "H"_ ((aq))^(+) + "Cl"_ ((aq))^(-)HCl(aq)H+(aq)+Cl(aq)

You can thus rewrite the equation as

2"Al"_ ((s)) + 6"H"_ ((aq))^(+) + 6"Cl"_ ((aq))^(-) -> ?2Al(s)+6H+(aq)+6Cl(aq)?

Remember, the stoichiometric coefficient of the hydrogen ions must also be distributed to the chloride anions, since

6"HCl"_ ((aq)) -> 6"H"_ ((aq))^(+) + 6"Cl"_((aq))^(-)6HCl(aq)6H+(aq)+6Cl(aq)

Now, when aluminium reacts with hydrochloric acid, it gets oxidized to aluminium cations, "Al"^(3+)Al3+. At the same time, the hydrogen ions get reduced to hydrogen gas, "H"_2H2.

2"Al"_ ((s)) + 6"H"_ ((aq))^(+) + color(red)(cancel(color(black)(6"Cl"_ ((aq))^(-)))) -> "Al"_ ((aq))^(3+) + color(red)(cancel(color(black)(6"Cl"_ ((aq))^(-)))) + "H"_ (2(g)) uarr

As you can see ,the chloride anions are spectator ions, which is why the initial equation didn't include them

2"Al"_ ((s)) + 6"H"_ ((aq))^(+) -> "Al"_ ((aq))^(3+) + "H"_ (2(g)) uarr

Now all you have to do is balance the aluminium and hydrogen atoms

color(green)(|bar(ul(color(white)(a/a)color(black)(2"Al"_ ((s)) + 6"H"_ ((aq))^(+) -> 2"Al"_ ((aq))^(3+) + 3"H"_ (2(g)) uarr)color(white)(a/a)|)))

The products of the reaction will thus be aqueous aluminium cations, "Al"^(3+), and hydrogen gas, "H"_2.

If you want, you can add in the chloride anions to get

2"Al"_ ((s)) + 6"H"_ ((aq))^(+) + 6"Cl"_ ((aq))^(-) -> 2"Al"_ ((aq))^(3+) + 6"Cl"_ ((aq))^(-) + 3"H"_ (2(g)) uarr

This is equivalent to

2"Al"_ ((s)) + 6"HCl"_ ((aq)) -> 2"AlCl"_ (3(aq)) + 3"H"_ (2(g)) uarr

The single replacement reaction reaction between aluminium metal and hydrochloric acid produces aqueous aluminium chloride and hydrogen gas.