Period 3 Oxides in Acid-Base Reactions
Lajoy Tucker
Teacher
Contents
Introduction and Definitions
Oxides of period 3 can be classified as acidic, basic or amphoteric.
Basic oxides ( and ) react with acids.
Acidic oxides ( and ) react with bases.
is an amphoteric oxide which means it reacts with both acids and bases.
Period 3 Oxides with Water Explainer Video
Acid-Base Behaviour of Oxides
When writing equations to show the acidic or basic behaviour of oxides, it can be helpful to think about them as the acids or bases they form when in water, and then use the general equation:
Acid + Base Salt + Water
e.g. Sodium oxide (a basic oxide) reacting with an acid (e.g. )
In water, sodium oxide produces sodium hydroxide .
The reaction between sodium hydroxide and hydrochloric acid produces the salt sodium chloride and water as below:
The reaction between sodium oxide and hydrochloric acid therefore gives the same products as below:
Oxide | Acid/Base Character | Behaves like... | Example Reaction |
Basic | |||
Basic | |||
Amphoteric | (acts as a base) (acts as an acid) | ||
Acidic | |||
Acidic | |||
Acidic | |||
Acidic |
Remember that both and are insoluble in water and so will only react with hot, strong, concentrated acids and/or bases.
It is important that you can construct equations between period 3 oxides and acids or bases. Rather than learn equations by heart, use your core understanding of acid/base reactions to construct them.
Practice Question
Question 1
Write an equation for the reaction of phosphorus oxide with water and state of the resulting solution.
Answer:
Equation:
~1-2 (acidic)
Question 2
Use equations to illustrate the acid-base character of .
Answer:
is amphoteric, meaning it reacts with both acids and bases.
With acid:
With base:
Summary
Melting points vary due to different bonding and structures.
Basic oxides form alkaline solutions and react with acids to form a salt and water.
Acidic oxides form acidic solution and react with bases to form a salt and water.
Amphoteric oxide react with acids and bases.
is weakly acidic and insoluble in water.
No answer provided.