The properties of oxides
3 marks · NormalCopper(II) oxide is formed by heating copper in oxygen.
Copper(II) oxide reacts with hydrochloric acid to form copper(II) chloride and water.
Explain, with reasons, why copper(II) oxide is classified as a basic oxide. Include in your answer what type of element forms this oxide, and what is observed when it is added to hydrochloric acid.
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Copper(II) oxide is a basic oxide because it is a metal oxide that reacts with acids to form a salt and water. Copper is a metal, and its oxides are basic. When copper(II) oxide is added to hydrochloric acid, it reacts to form copper(II) chloride (a blue-green solution) and water.
Must show: Correctly explains metal/basic nature, Reaction with acid gives salt and water, Observation
Also accept: States black solid reacts to give blue-green solution
Common mistakes: States it is acidic; Forgets to mention reaction with acid
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Marking points
E1 · 1 mark · States copper(II) oxide is a basic oxide because it is a metal oxide.
E2 · 1 mark · Explains that basic oxides react with acids to form salt and water.
E3 · 1 mark · Describes observation: black solid dissolves, blue-green copper(II) chloride formed.
Worked solution
Copper(II) oxide is a basic oxide as it is formed from a metal (copper). Basic oxides react with acids to form a salt and water. When copper(II) oxide (a black solid) is added to hydrochloric acid, it reacts and forms a blue-green solution of copper(II) chloride and water.