Did you ever wonder an oxide could be simple and complex? Well, as students of chemistry, we have to look into the depths of everything. So, while studying oxides, we have to look at simple oxide. In this chapter, we will read all about simple oxides, their types, and properties. However, do you first know what an oxide is?
What is an Oxide?
An oxide is a binary compound that we obtain upon the reaction of oxygen with other elements. Depending on the oxygen content, we can extensively arrange them into mixed and simple oxides. An oxide of a nonmetal generally has a tendency to be acidic.
On the other hand, an oxide a of metal shows a basic tendency. The oxides of elements in or close to the corner band of semimetals are by and large amphoteric. Let us now look at the different types of oxides.
We get a mixed oxide upon the combination of two simple oxides. Examples of these include: Lead dioxide (PbO2) and lead monoxide (PbO) combine to form the mixed oxide Red lead (Pb3O4). In another example, we can see that Ferric oxide (Fe2O3) and ferrous oxide (FeO) combine and form the mixed oxide Ferro-ferric oxide (Fe3O4).
Classification of Simple Oxides
On the basis of their chemical behaviour, there are acidic, basic, amphoteric and neutral oxides.
1) Acidic Oxide
An acidic oxide reacts with water and produces an acid. Usually, it is the oxide of non-metals. Examples include SO2, CO2, SO3, Cl2O7, P2O5, and N2O5. It could also be the oxide of metals with high oxidation states, such as CrO3, Mn2O7, and V2O5.
- Sulphur dioxide reacts with water and gives sulphurous acid.
SO2 + H2O → H2SO3
- Chromic anhydride reacts with water and results in chromic acid.
Cr2O3 + H2O → H2Cr2O4
2) Basic Oxide
A basic oxide reacts with water to give a base. Examples include the oxide of most metals, such as Na2O, CaO, BaO. These are basic in nature.
- Calcium oxide reacts with water and produces calcium hydroxide, a base.
CaO + H2O → Ca(OH)2
3) Amphoteric Oxide
An amphoteric oxide is that metallic oxide displaying a dual behaviour. It shows the characteristics of both an acid as well as a base. It reacts with both alkalis as well as acids.
- For example, zinc oxide acts as an acidic oxide when it reacts with concentrated sodium hydroxide. However, it acts as a basic oxide while reacting with hydrochloric acid.
ZnO + 2H2O + 2NaOH → Na3Zn[OH]4 + H2
ZnO + 2HCl → ZnCl2 + H2O
- Aluminium oxide is another example that reacts with alkalis as well as acids.
Al2O3(s) + 6NaOH(aq) + 3H2O(l) → 2Na3[Al(OH)6](aq)
Al2O3(s) + 6HCl(aq) + 9H2O(l) → 2[Al(H2O)6]3+(aq) + 6Cl–(aq)
Solved Example for You
Q: What is a neutral oxide?
Ans: A neutral oxide is one that does not exhibit any tendency to form salts either with acids or bases. The examples of neutral oxides include nitrous oxide and carbon monoxide.