The table below shows observations made during a recycling trial. Small pieces of each metal oxide were heated strongly with powdered carbon in separate har...
Question 1 Report
The table below shows observations made during a recycling trial. Small pieces of each metal oxide were heated strongly with powdered carbon in separate hard-glass tubes. The same mass of oxide and carbon was used each time. A technician checked for a metal after cooling. Carbon can remove oxygen from the oxide only when the metal is less reactive than carbon.
| metal oxide heated with carbon | observation after heating |
|---|---|
| copper(II) oxide | red-brown metal formed |
| iron(III) oxide | grey metal particles formed |
| aluminium oxide | white solid unchanged |
(a) State the colour change when black copper(II) oxide is reduced in this trial. [1]
(b) Which metal is more reactive than carbon? [1]
(c) Give the name of the substance that removes oxygen from copper(II) oxide. [1]
(d) Explain why aluminium oxide does not give aluminium in this method. [2]
(e) Complete the equation: 2CuO + C → 2Cu + ............ [1]
(f) State one safety precaution when heating a solid in a hard-glass tube. [1]
(g) Name the type of reaction in which oxygen is removed from a metal oxide. [1]
Answer Details
(a) The colour change is black to red-brown: black copper(II) oxide is changed into copper metal. [1]
(b) Aluminium is more reactive than carbon, shown by its oxide remaining unchanged. [1]
(c) Carbon removes oxygen from copper(II) oxide. It is the reducing agent. [1]
(d) Aluminium is more reactive than carbon, so carbon cannot remove oxygen from aluminium oxide. Therefore aluminium metal is not made by this method. [2]
(e) \[\mathrm{2CuO + C \rightarrow 2Cu + CO_2}\] The missing product is \(\mathrm{CO_2}\). [1]
(f) Wear eye protection when heating the tube. Pointing the tube away from people, or using a clamp or tongs, are also suitable precautions. [1]
(g) Removal of oxygen from a metal oxide is called reduction. [1]
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