Question

1. write the net ionic equation for the neutralization of the bases, magnesium hydroxide, mg(oh)₂ and aluminum hydroxide, al(oh)₃, found in maalox®, for example, with acid (h⁺).

Explanation:

Step1: For Magnesium Hydroxide

Magnesium hydroxide is a base, and in neutralization with acid ($\ce{H+}$), the base dissociates to give $\ce{Mg^2+}$ and $\ce{OH-}$ ions. The neutralization reaction involves $\ce{OH-}$ reacting with $\ce{H+}$. The formula for magnesium hydroxide is $\ce{Mg(OH)2}$, which is a solid (insoluble in water to a large extent but reacts with acid). The net ionic equation for the reaction of $\ce{Mg(OH)2(s)}$ with $\ce{H+(aq)}$ is:
$\ce{Mg(OH)2(s) + 2H+(aq) -> Mg^2+(aq) + 2H2O(l)}$

$\ce{Mg(OH)2}$ is a solid, so it doesn't dissociate into ions in the net ionic equation. $\ce{H+}$ from the acid reacts with $\ce{OH-}$ from the base (released when $\ce{Mg(OH)2}$ reacts with acid) to form water, and $\ce{Mg^2+}$ is a product.

Step2: For Aluminum Hydroxide

Aluminum hydroxide is $\ce{Al(OH)3(s)}$. When it reacts with $\ce{H+(aq)}$ (acid), the net ionic equation is:
$\ce{Al(OH)3(s) + 3H+(aq) -> Al^3+(aq) + 3H2O(l)}$

$\ce{Al(OH)3}$ is a solid, so it remains as a formula unit. $\ce{H+}$ reacts with the $\ce{OH-}$ groups in $\ce{Al(OH)3}$ to form water, and $\ce{Al^3+}$ is released into the solution.

Answer:

For $\ce{Mg(OH)2}$: $\boldsymbol{\ce{Mg(OH)2(s) + 2H+(aq) -> Mg^2+(aq) + 2H2O(l)}}$
For $\ce{Al(OH)3}$: $\boldsymbol{\ce{Al(OH)3(s) + 3H+(aq) -> Al^3+(aq) + 3H2O(l)}}$