Transcript Acid and Bases - AIS IGCSE Science

Acid and Bases
-Types of OxidesMany 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 oxides
 basic oxides
 amphoteric oxides
 neutral oxides

Acidic oxides
Oxides of non-metal
 Acidic oxides are often gases at room
temperature.

Acidic oxides

React with water to produce acids.

Example:
sulphur trioxide + water
SO3 + H2O
sulphuric acid
H2SO4
Acidic oxides

React with bases and alkalis to produce salts

Example:
carbon dioxide + sodium hydroxide
CO2 + 2NaOH
sodium carbonate + water
Na2CO3 + H2O
Examples of acidic oxides
Acidic Oxide
Formula
Acid Produced with
Water
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
MgO + 2HCl
magnesium chloride + water
MgCl2 + H2O
This is a neutralisation reaction
Examples of basic oxides
Basic Oxide
Formula
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 + hydrochloric
acid
oxide

aluminium
+
chloride
water
sodium +
aluminate
water
aluminium oxide as an acid
aluminium
sodium
+ hydroxide
oxide
Neutral oxides

Non-metals that form oxides that show neither
basic nor acidic properties.
 Insoluble in water.
Examples of neutral oxides
Neutral Oxide
Formula
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