Classifying Oxides

07 April 2023
Classifying Oxides
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Slide 1: Tekstslide
PhysicsSecondary EducationAge 12,13

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07 April 2023
Classifying Oxides

Slide 1 - Tekstslide

Content objectives
  • I can classify oxides as acidic, including SO2 and CO2, or basic, including CuO and CaO, related to metallic and non-metallic character.
  • I can describe amphoteric oxides as oxides that react with acids and with bases to produce a salt and water.
  • I can classify Al2O3 and ZnO as amphoteric oxides.

Slide 2 - Tekstslide

Proton Transfer

Slide 3 - Tekstslide

What are oxides?
  • Oxides are compounds made from one or more atoms of oxygen combined with one other element.
  • Examples of oxides include: MgO, ZnO, K2O, CO2, SO2, H2O
  • Oxides can be classified based on their acid-base characteristics.

Slide 4 - Tekstslide

Acid and basic oxides
  • have different properties and values of pH
  • the difference in their pH = whether they are bonded to a metal or to a non-metal element
  • The metallic character of the element influences the acidic or basic behaviour of the molecule.

Slide 5 - Tekstslide

Slide 6 - Tekstslide

Acidic Oxides
  • formed when a non-metal element combines with oxygen
  • react with bases to form a salt and water
  • When dissolved in water, they produce an acidic solution with a low pH.
  • Common examples include CO2, SO2, NO2 and SiO2

Slide 7 - Tekstslide

Basic Oxides
  • formed when a metal element combines with oxygen
  • react with acids to form a salt and water
  • When dissolved in water they produce a basic solution with a high pH.
  • Common examples include CuO and CaO

Slide 8 - Tekstslide

07 April 2023
Classifying Oxides

Slide 9 - Tekstslide

Neutral Oxides
  • Some oxides do not react with either acids or bases and thus are said to be neutral.
  • Examples include N2O, NO, and CO.

Slide 10 - Tekstslide

Amphoteric oxides
  • a group of oxides that can behave as both acidic and basic, depending on whether the other reactant is an acid or a base
  • In both cases, salt and water are formed.
  • most common amphoteric oxides: zinc oxide, ZnO and aluminum oxide, Al2O3
  • The hydroxides of both of these elements also behave amphoterically.

Slide 11 - Tekstslide

Example
  • Example of aluminium oxide behaving as a base:

Al2O3 + 6HCl → 2AlCl3 + 3H2O

  • Example of aluminium oxide behaving as an acid:

Al2O3 + 2NaOH → 2NaAlO2 + H2O

Slide 12 - Tekstslide

Exemption to the Proton transfer concept
  • This acidic and basic behaviour of amphoteric oxides is not easily explained by donating or accepting protons. A separate theory called the Lewis acid-base theory can identify acids or bases in these situations.

Slide 13 - Tekstslide