Reactions with amphoteric oxides

Reactions with amphoteric oxides are chemical phenomena in which this class of oxides are reactants in a medium with a inorganic base or one inorganic acid.

Note:amphoteric oxides they are those that have in their constitution only the elements zinc, lead, beryllium and tin.

Regardless of the reaction with amphoteric oxide present as the second reactant an acid or a base, the products formed in this type of reaction will always be the same, that is, a salt and water, as shown in the generic equation below:

amphoteric oxide + acid → salt + H₂O

or

amphoteric oxide + base → salt + H₂O

Reactions of amphoteric oxides with acid

When an amphoteric oxide reacts with acid (HX), it forms a salt and water. This salt is formed by the interaction between the cation (Y) of the oxide and the anion (X) of the acid, and water is produced in the interaction between the hydrogen in the acid and the oxygen in the oxide, as can be seen in equation below:

YO + HX → YX + H₂O

If amphoteric lead oxide IV (PbO₂) react with phosphoric acid (H₃DUST₄), for example:

PbO₂ + H₃DUST₄ →

We will have the formation of the IV lead phosphate salt [Pb₃(DUST₄)₄] from the interaction of the Pb cation⁺⁴ of the oxide with the phosphate anion (PO₄^-3) of the acid, and the interaction of the hydronium cation (H⁺) of the acid with the anion (O^-2) of the oxide. Thus, the balanced equation of this process will be:

3 PbO₂+ 4 hours₃DUST₄ → Pb₃(DUST₄)₄ + 6 H₂O

Amphoteric oxide based reactions

When the amphoteric oxide reacts with an inorganic base (WOH), salt and water will form, as shown in the generic equation below:

YO + WOH → WYO_no + H₂O

Salt is formed from the interaction between the cation (W⁺) of the base with the anion (Yo_no), formed by the metal present in the oxide. Below, see a list containing the anions formed by the common metals of amphoteric oxides:

Table with anions formed by some metals

If, for example, aluminum oxide (Al₂O₃) react with barium hydroxide [Ba(OH)₂]:

Al₂O₃ + Ba(OH)₂ →

The barium cation (Ba⁺²) of the base must interact with the aluminate anion (AlO₂^-1), formed by the aluminum present in the oxide, which will give rise to the barium aluminate salt [Ba (AlO₂)₂], and water will be formed from the base hydroxyls. Check out the balanced equation for this process below:

1 Al₂O₃ + 1 Ba (OH)₂ → 1 Ba (AlO₂)₂ + 1 hour₂O

By Me. Diogo Lopes Dias

Source: Brazil School - https://brasilescola.uol.com.br/quimica/reacoes-com-oxidos-anfoteros.htm