Video Transcript
Which of the following oxides is considered a basic oxide? (A) SO2, (B) SO3, (C) CO2, (D) Na2O, or (E) P2O5.
In this question, we want to determine which of the listed compounds is considered a
basic oxide.
An oxide is a chemical compound that contains at least one oxygen atom chemically
bonded to an atom of another element. There are many different oxide compounds. A few common examples include carbon dioxide, water, and nitrous oxide, also called
laughing gas. These three examples are oxides with nonmetals. However, oxides can also be formed with metals. One example is calcium oxide, which has many uses including the industrial production
of porcelain and glass.
Many oxides can be classified as a base or an acid, while some oxides are considered
neutral and others are amphoteric. We will focus on identifying the basic oxide, which means it can produce a solution
with a pH above seven, while an acidic oxide solution has a pH below seven. This can be determined by knowing the electronegativity of the other elements.
Electronegativity increases across the periodic table from left to right. The acidity of oxides increases with the electronegativity of the elements bonded to
oxygen. So therefore, oxide acidity increases from left to right on the periodic table. Metallic elements compose the left portion of the periodic table. Metals will tend to form basic oxides. Alternatively, as nonmetals are on the right side of the periodic table, they will
tend to form acidic oxides.
Let’s look to see where the elements bonded to oxygen in the answer choices are
located on the periodic table. Answer choices (A), (B), (C), and (E) are oxides that contain nonmetals in addition
to oxygen. These oxides would form acidic oxides and thus are not the answer to this
question. Answer choice (D), Na2O or sodium oxide, is a metal oxide and would be considered
basic. Therefore, the oxide that would be considered a basic oxide is answer choice (D),
Na2O.
