What is an oxide?

An oxide is a Binary compound of oxygen and another element.

M & OOxides can be classified in two

ways –

1.Nature of Oxides

2.Amount of Oxygen present

Most oxides can be grouped into four types:

1. acidic oxides

2. basic oxides

3. amphoteric oxides

4. neutral oxides

1. Types of Oxides based on their nature

1. Acidic oxides

Oxides of non-metalAcidic oxides are often gases at room

temperature.

Acidic oxides

React with water to produce acids.

Example:

sulphur trioxide + water sulphuric acid

SO3 + H2O H2SO4

Acidic oxides

React with bases and alkalis to produce salts

Example: carbon dioxide + sodium hydroxide sodium carbonate + water

CO2 + 2NaOH Na2CO3 + H2O

Acidic oxides

• React with basic oxides to produce salts

SiO2 + MgO MgSiO3

Examples of acidic oxides

Acidic OxideAcidic Oxide FormulaFormula Acid Produced with Acid Produced with WaterWater

sulphur trioxide SO3 sulphuric acid, H2SO4

sulphur dioxide SO2 sulphurous acid, H2SO3

carbon dioxide CO2 carbonic acid, H2CO3

phosphorous(V) oxide

P4O10 phosphoric acid, H3PO4

Basic oxides

Oxides of metal Basic oxides are often solids at room

temperature. Most basic oxides are

insoluble in water.

Calcium oxide (quicklime)

Basic oxides

React with acids to produce salts and water only.Example: Magnesium oxide + hydrochloric acid magnesium

chloride + water

MgO + 2HCl MgCl2 + H2O

This is a neutralisation reaction

Examples of basic oxides

Basic OxideBasic Oxide FormulaFormula

magnesium oxide MgO

sodium oxide Na2O

calcium oxide CaO

copper(II) oxide CuO

Amphoteric oxides

Oxides of metal Can behave as acidic oxides

or as basic oxides

Zinc oxide

Amphoteric oxides

React with acids and alkalis to produce salts Example: aluminium oxide (Al2O3)

aluminium oxide as a base

aluminium oxide as an acid

hydrochloric acid

aluminium chloride wateraluminium

oxide+ +

aluminium oxide

sodium hydroxide

sodium aluminate

water+ +

Neutral oxides

Non-metals that form oxides that show neither basic nor acidic properties.

Insoluble in water.