Question

Why is the reaction of Al with water much slower than Al with HCl?

Answer 1

Dilute acids react with relatively reactive metals such as Mg, Al, Zn and Fe. The products of the reaction are a salt (AlCl₃) and hydrogen gas (H₂) . The more reactive the metal, the faster the reaction. However, aluminium has a protective oxide layer, so it reacts slowly with HCl to begin with.