Classification of oxides

Introduction

Oxides are chemical compounds in which one or more oxygen atoms are bonded with another element to form a chemical molecule (e.g. Li2O). Oxides are oxygen-containing compounds that contain other elements, such as CO2, SO2, CaO, CO, ZnO, BaO2, H2O, and so on. These are referred to as oxides since oxygen is present in only one elemental combination in this case. Acidic oxides are distinguished from basic oxides, which are distinguished from amphoteric oxides, which are distinguished from neutral oxides. Acidic oxide is a phrase used to describe an oxide that reacts with water to produce an acid. A basic oxide is an oxide that produces a base in water when it comes into contact with it. When it comes to chemical reactions, an amphoteric solution is a material that can respond as either an acid or a base.

In contrast, it is also possible for oxide to be neither acidic nor basic, but rather to be a neutral oxide, which is described below. There are a number of different characteristics that can be used to distinguish between the three types of oxides. The term anhydride (which means “without water”) refers to substances that assimilate H2O and react with it to generate either an acid or a basic when water is added.

Classification Of Oxides

In accordance with their nature and the characteristics exhibited by compounds, they are divided into three categories.

Acidic Oxides

When water is added to acidic oxides (Groups 14-17), the acid anhydrides are formed, which are acidic in nature:

Sulfuric Acid is a kind of acid.

SO2+H2O→H2SO3..(1)

Sulfuric Acid

SO3+H2O→H2SO4…(2)

Carbonic Acid is a type of acid that occurs naturally in the environment.

CO2+H2O→H2CO3..(3)

Chemically, acidic oxides (e.g., sulphur dioxide is sulphurous anhydride and sulphur trioxide is sulfuric anhydride) are referred to as acid anhydrides; when mixed with bases, these anhydrides form salts, such as sodium chloride.

SO2+2NaOH→Na2SO3+H2O…(4)

Basic Oxides

Generally, Group 1 and Group 2 elements combine to generate bases known as base anhydrides or basic oxides, such as, for example, sodium chloride.

K2O(s)+H2O(l)→2KOH(aq)…(5)

The oxides of metals are classified as basic oxides. If they are soluble in water, they react with the water to form hydroxides (alkalies), for example, sodium hydroxide.

CaO+H2O→Ca(OH)2...(6)

MgO+H2O→Mg(OH)2..(7)

Na2O+H2O→2NaOH…(8)

These metallic oxides are referred to as basic anhydrides in the scientific community. They react with acids to form salts, such as sodium chloride.

MgO+2HCl→MgCl2+H2O(9)

Na2O+H2SO4→Na2SO4+H2O..(10)

Amphoteric Oxides

When it comes to chemical reactions, an amphoteric solution is a material that can respond as either an acid or a base. When HSO4–interacts with water, it produces both hydroxide and hydronium ions, as seen in the following example:

HSO4–+H2O→SO4−2+H3O+…(11)

 HSO4– +H2O→H2SO4+OH−….(12)

Amphoteric oxides have both basic and acidic characteristics, which makes them useful in many applications. When they react with an acid, they form salt and water, which are both substances having fundamental features. Acidic characteristics are formed when they react with alkalies, resulting in the formation of salt and water.

For example, ZnO exhibits fundamental behaviour when exposed to HCl.

ZnO+2HCl→ZnCl2 +H2O (basicnature)…(13)

as well as acidic behaviour when using NaOH

ZnO+2NaOH→Na2ZnO2 + H2O (acidicnature)…(14)

Similarly, Al2O3 shows fundamental behaviour when combined with H2SO4.

Al2O3+3H2SO4→Al2(SO4)3 +3H2O (basicnature)…..(15)

as well as acidic behaviour when using NaOH

Al2O3+2NaOH→2NaAlO2+H2O (acidicnature)….(16)

Neutral Oxides

Neutral oxides have neither basic nor acidic qualities, and as a result, when they react with acids or bases, they do not create salts. Examples of neutral oxides include carbon monoxide (CO), nitrous oxide (N2O), nitric oxide (NO), and others.

Peroxides and Dioxides are two types of peroxides.

ionic oxides (M2O): Group 1 metals react swiftly with oxygen to yield a variety of distinct ionic oxides, most of which are found in solution. Because the oyxgen has an oxidation number of -2, it is a reactive gas.

4Li+O2→2Li2O….(17)

Excess oxygen is frequently used to generate the peroxide M2O2 when lithium and sodium react with each other. The oxidation number of the oxygen is equal to -1.

H2+O2→H2O2….(18)

Superoxides: Potassium, Rubidium, and Cesium are frequently found reacting with excess oxygen to form the superoxide, MO2, which has an oxidation number equal to -1/2.

Cs+O2→CsO2….(19)

A peroxide is a metallic oxide that, when exposed to dilute acids, decomposes to produce hydrogen peroxide. They contain more oxygen than the corresponding basic oxide, for example, sodium, calcium, and barium peroxides, which are all oxygen-containing.

BaO2+H2SO4→BaSO4+H2O2….(20)

Na2O2+H2SO4→Na2SO4+H2O2….(21)

PbO2 and MnO2 are examples of oxides that contain a higher amount of oxygen than peroxides and have molecular formulas that are comparable to peroxides. These oxides, on the other hand, do not produce hydrogen peroxide when in contact with dilute acids. When dioxides react with concentrated HCl, Cl2 is produced, and when dioxides react with concentrated H2SO4, O2 is produced.

PbO2+4HCl→PbCl2+Cl2+2H2O….(22)

2PbO2+2H2SO4→2PbSO4+2H2O+O2…(23)

Compound Oxides

Chemically, compound oxides are metallic oxides that behave as if they are made up of two oxides, one of which has a lower oxidation and the other of which has a higher oxidation of the same metal, for example, iron oxide and tin oxide.

Pb3O4→PbO2+2PbO is the formula for red lead (24)

Ferro-ferric oxide: Fe3O4→Fe2O3+FeO…(25)

Compound oxides are transformed into a mixture of salts when exposed to an acid.

Fe3O4 +8HCl→2FeCl3+FeCl2+4H2O… (26)

Conclusion

It is possible to divide oxides into three groups based on the acid-base characteristics of the compounds. These are neutral, amphoteric, and basic or acidic. It is an acidic oxide when it reacts with water and releases acid into the surrounding environment. The compound basic oxide is defined as an oxide that, when mixed with water, produces a base.

One of the most important basic oxides is magnesium oxide (MgO), which is a good thermal conductor and electrical insulator that is used in firebrick as well as thermal insulation, and calcium oxide (CaO), also known as quicklime or lime, which is used extensively in the steel industry as well as in water treatment.