Oxides: Basic Oxides, Acidic Oxides, Amphoteric Oxides, Neutral Oxides, Peroxides and Higher Oxides

Elements combine with Oxygen to form various oxides. Oxides formed are classified into acidic oxides, basic oxides, amphoteric oxides, neutral oxides, peroxides and higher oxides. Here is a detailed description of each of the oxides.

Basic Oxides are metallic Oxides that reacts with Acids (like Alkalis) to form only salt and water. Two examples of basic Oxides are Sodium (I) Oxide Na₂O and Lead (II) Oxide PbO.

The Ionic equation for the two basic oxides above are similar in terms of both quantisation and participating Ions.

O^2-(s) + 2H⁺(aq) → H₂O(l)

An extraction of the reaction of Sodium Oxide with acid to form salt and water shows that one mole of sodium oxide reacts with two moles of hydrochloric acid to form two moles of sodium chloride and one mole of water.

Na₂O(s) + 2HCl(aq) → 2NaCl(aq) +H₂O(l)

And Lead Oxide also reacts with trioxonitrate (V) to form the corresponding salt (Lead (II) trioxonitrate five salt) and water.

PbO(s) + 2HNO₃(aq) → Pb(NO₃)₂(aq) + H₂O(l)

Acid Oxides, as the name implies, are oxides of nonmetals that reacts with water to form Acids. This can be expressed Ionically in the reaction of carbon (IV) Oxide gas with hydroxide Alkali to form trioxocarbonate salt and water.

CO₂(g) + 2OH^-(aq) → CO₃^2-(aq) + H₂O(l)

Like normal Acids, Acidic oxides also react with Alkalis to form salt and water.

SO₃(g) + 2KOH(aq) → K₂SO₄(aq) + H₂O(l)

Nitrogen (IV) oxide on the other hand is an acidic oxide, but referred to as double anhydride because of its ability to form two salts: Sodium trioxonitrate (V) and sodium dioxonitrate (III), with sodium hydroxide.

2NO₂(g) + 2NaOH(aq) → NaNO₃(aq) + NaNO₂(aq) + H₂O(l)

The equation of reaction of acidic oxide is as shown in the reaction of carbon (IV) oxide with sodium hydroxide to form sodium trioxocarbonate (IV) salt and water.

CO₂(g) + 2NaOH(aq) → Na₂CO₃(aq) + H₂O(l)

And the reaction of SO_3,

SO₃(g) + 2KOH(aq) → K₂SO₄(aq) + H₂O(l)

It must also be stated that there are other Oxides called the Neutral Oxides. Neutral oxides are mostly detected by their neutrality to litmus test since they are neither acidic or basic. Examples of Neutral Oxides are Nitrogen (I) Oxide, Water and Carbon (II) Oxide.

A third type of Oxide is the Amphoteric Oxides. Amphoteric oxides are characterised by having both the attributes of Acidic Oxides and Basic Oxides. They can react with acids as well as alkalis to form corresponding salts and water. These Oxides includes the Oxides of Aluminium, Lead, Tin and Zinc.

Amphoteric Oxides behaves as Bases in the presence of acids. This is as expressed by Zinc Oxides and Tetraoxosulphate (VI) Acid.

ZnO(s) + H₂SO₄(aq) → ZnSO₄(aq) + H₂O(l)

And the reaction of Aluminium Oxide with Hydrochloric acid.

Al₂O₃(s) + 6HCl(aq) → 2AlCl₃(aq) 3H₂O(l)

In the presence of bases on the other hand, they become Acids. Take for example the reaction of Zinc (II) Oxide With Sodium Hydroxide where the Zinc (II) Oxide behaves as an Acid.

ZnO(s) + 2NaOH(aq) + H₂O(l) → Na₂Zn(OH)₄(aq)

And Aluminium Oxide in the presence of sodium hydroxide also behaves as an Acid.

Al₂O₃(s) +2NaOH(aq) + 3H₂O(l) → 2NaAl(OH)₄(aq)

Both reactions above can be expressed ionically. The ionic equation for Zinc (II) Oxide is as expressed by the reaction bellow producing Zincate (II) Ion.

ZnO(s) + 2OH^-(aq) + H₂O(l) → [Zn(OH)₄]²(aq)

While the Aluminium Oxide Equation evidently result to the formation of Aluminium (II) Ion.

Al₂O₃(s) + 2OH^-(aq) + 3H₂O(l) → 2[Al(OH)₄]^-(aq)

Peroxides are any Oxides that contain the peroxide ion: (O-O)². They form hydrogen peroxid (H₂O₂) when reacted with dilute acid. Typical peroxides are sodium peroxides (Na₂O₂), calcium peroxid (CaO₂) and barium peroxide (BaO₂). An explanation of how peroxides react with dilute acids to form Hydrogen peroxide is as explained by the action of dilute tetraoxosulphate (VI) acid on barium oxide.

BaO₂ + H₂SO₄(aq) → BaSO₄(s)+ H₂O₂(aq)

There are other oxides that contain higher amount of oxygen but unlike peroxides, higher oxides do not form hydrogen peroxide when reacted with dilute acids. Instead they liberate Oxygen with heat, thus making them Oxidizing agents. Examples of higher oxides are Manganese(IV) Oxide (MnO₂₎, Lead(IV) oxide (PbO₂), Iron(II) diiron(III) oxide (Fe₃O₄) and dilead(II) lead(IV) oxide (Pb₃O₄).