Video Transcript
ZnO is an oxide that can react with both acids and bases, as shown in the following
equations. ZnO plus H2SO4 produces ZnSO4 plus H2O, and ZnO plus two NaOH produces Na2ZnO2 plus
H2O. What name is given to an oxide that reacts with both acids and bases?
This question is asking us about a category of oxide. Oxides are compounds that contain oxygen, such as magnesium oxide, carbon dioxide,
zinc oxide, and dinitrogen oxide. The oxide of interest here is zinc oxide.
The two reactions shown are neutralization reactions. In a neutralization reaction, an acid and a base combine to form water and some form
of salt. In the upper reaction, zinc oxide acts as a base, combining with sulfuric acid. Interestingly, in the lower reaction, zinc oxide acts as an acid when it combines
with sodium hydroxide, a base. Zinc oxide can indeed react with both acids and bases.
In order to know what name we give this group of oxides, let’s review some categories
of oxide. Some oxides, like magnesium oxide, are basic oxides. Basic oxides will neutralize acids like in the upper reaction shown here. Basic oxides also combine with water to form a basic solution. Basic oxides are often metal oxides, meaning that the compound contains oxygen and a
metal element. Oxides like carbon dioxide are acidic oxides. They will neutralize bases like in the bottom equation drawn here. They combine with water to form acidic solutions. Often, acidic oxides are nonmetal oxides.
Since zinc oxide reacts with both acids and bases, we give it a special name. We call these oxides amphoteric oxides. The word “amphoteric” comes from the Greek word for both, similar to how an amphibian
lives on both land and water. The last category neutral oxides, like dinitrogen oxide, do not react with acids or
bases.
So, what name is given to an oxide that reacts with both acids and bases? The correct answer is amphoteric.