Acid and Bases -Types of Oxides- Many acids and alkali are formed by dissolving oxides in water.

Acid and Bases

-Types of Oxides-Many acids and alkali are formed by

dissolving oxides in water

At the end of this e-learning, you should able to:

Classify oxides as acidic, basic, amphoteric or neutral based on metallic/non-metallic character

What is an oxide?

An oxide is a compound of oxygen and another element.

Most oxides can be grouped into four types: acidic oxidesbasic oxidesamphoteric oxidesneutral oxides

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

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.

Examples of neutral oxides

Neutral OxideNeutral Oxide FormulaFormula

water H2O

carbon monoxide CO

nitric oxide NO

How can we classify an unknown oxide?

First question:

Does the oxide dissolve in acid?

YES NO

It is either a basic or amphoteric oxide.

Next question:

Is the oxide soluble in alkali?

Soluble Insoluble

It is either an acidic or neutral oxide.

Next question:

Is the oxide soluble in alkali?

Soluble Insoluble

Amphoteric oxide

What is an amphoteric oxide?

Back to first question

Basic oxide

What is a basic oxide?

Cook an egg with calcium oxide

Back to first question

Acidic oxide

What is an acidic oxide?

How does acidic oxide affects the atmosphere?

Back to first question

Neutral oxide

What is an neutral oxide?

Back to first question

Back to the first slide