Oxides (Cambridge O Level Chemistry)

Topic Questions

1a3 marks

Zirconium (Zr) is a metal in Period 5. Its main oxidation state is +4.

The following are all zirconium atoms: Zr presubscript 40 presuperscript 90Zr presubscript 40 presuperscript 91Zr presubscript 40 presuperscript 92.

In terms of numbers of electrons, neutrons and protons, how are these three atoms the same and how are they different?


They are the same because ...


They are different because ...

1b2 marks

Above 900°C, zirconium reacts with water to form zirconium(IV) oxide, ZrO2, and hydrogen. Write an equation for this reaction.

1c4 marks

It is possible to determine whether zirconium(IV) oxide is acidic, neutral, basic or amphoteric using an acid and an alkali. Complete the table of possible results. If the oxide is predicted to react write ‘R’, if it is predicted not to react write ‘NR’.

if the oxide is predicted result with hydrochloric acid predicted result with aqueous sodium hydroxide
acidic    
basic    
neutral    
amphoteric    

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1a4 marks

Gallium is a metallic element in Group III. It has similar properties to aluminium.

i)
Describe the structure and bonding in a metallic element. You should include a labelled diagram in your answer.
[3]
ii)
Explain why metallic elements such as gallium are good conductors of electricity.
[1]
1b2 marks

Give the formula of


Gallium(III) chloride ......................................

Gallium(III) sulfate ........................................
1c4 marks

Gallium(III) oxide, Ga2O3, is amphoteric.

i)
Write the chemical equation for the reaction between gallium(III) oxide and dilute nitric acid to form a salt and water only.

[2]

ii)
The reaction between gallium(III) oxide and sodium hydroxide solution forms only water and a salt containing the negative ion Ga2O42–.

Write the chemical equation for this reaction.

[2]

1d2 marks

Alloys of gallium and other elements are often more useful than the metallic element itself.


Suggest two reasons why alloys of gallium are more useful than the metallic element.

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2a1 mark

This question is concerned with the following oxides.

   aluminium oxide
   carbon monoxide
   copper(II) oxide
   silicon(IV) oxide
   sodium oxide
   sulfur dioxide
   zinc oxide

Choose one oxide from the above list to match each of the following descriptions. An oxide may be used once, more than once or not at all.

This oxide does not react with acid or alkali.

2b1 mark

This oxide reacts with water to give a strong alkali solution.

2c1 mark

This oxide is used as a bleach.

2d1 mark

This oxide is amphoteric.

2e1 mark

This oxide has a giant covalent structure.

2f1 mark

This oxide is soluble in water and it is acidic.

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3a4 marks

This question is concerned with the following oxides.

sulfur dioxide
carbon monoxide
lithium oxide
aluminium oxide
nitrogen dioxide
strontium oxide

i)
Which of the above oxides will react with hydrochloric acid but not with aqueous sodium hydroxide?
[1]

ii)
Which of the above oxides will react with aqueous sodium hydroxide but not with hydrochloric acid?
[1]

iii)
Which of the above oxides will react with both hydrochloric acid and aqueous sodium hydroxide?
[1] 

iv)
Which of the above oxides will not react with hydrochloric acid or with aqueous sodium hydroxide?
  [1]
3b5 marks

Two of the oxides are responsible for acid rain.

Identify the two oxides and explain their presence in the atmosphere.

3c3 marks

Lithium oxide is an ionic compound.

i)
Identify another ionic oxide in the list in part a)
[1]
ii)
Draw a diagram which shows the formula of lithium oxide, the charges on the ions and the arrangement of the valency electrons around the negative ion.

Use x to represent an electron from an atom of oxygen.
Use o to represent an electron from an atom of lithium.
[2]

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41 mark

Choose from the list of oxides to answer the questions.

calcium oxide

carbon dioxide

copper(II) oxide

silicon(IV) oxide

sodium oxide

sulfur dioxide

sulfur trioxide

zinc oxide

Each oxide can be used once, more than once or not at all. Identify which oxide:

has a giant covalent structure

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