Zinc can be extracted from zinc sulfide, ZnS\text{ZnS}ZnS, in two stages.
Stage 1: Zinc sulfide is heated in air. It reacts with oxygen to produce zinc oxide and sulfur dioxide.
Stage 2: The zinc oxide is then heated in a furnace with coke.
Write a chemical equation for the reaction in Stage 1.
The equation for the reaction that occurs when zinc oxide is heated with coke is:
2ZnO+C→2Zn+CO2 2\text{ZnO} + \text{C} \rightarrow 2\text{Zn} + \text{CO}_2 2ZnO+C→2Zn+CO2State, with a reason, whether ZnO\text{ZnO}ZnO is oxidised or reduced in this reaction.
Calculate the minimum mass, in tonnes, of coke needed to react with 40.7 tonnes40.7\text{ tonnes}40.7 tonnes of zinc oxide. [1 tonne=106 g1\text{ tonne} = 10^6\text{ g}1 tonne=106 g; relative atomic masses: Ar(Zn)=65.4A_r(\text{Zn}) = 65.4Ar(Zn)=65.4, Ar(O)=16A_r(\text{O}) = 16Ar(O)=16, Ar(C)=12A_r(\text{C}) = 12Ar(C)=12]
The molten lead obtained from some blast furnaces contains 0.2% gold dissolved as an impurity.
The gold is removed by:
Use the information above to answer the following questions:
What can you deduce about the relative solubility of gold in zinc and in lead?
What can you deduce about the melting point of the mixture of zinc and gold?
What can you deduce about the boiling point of zinc compared to that of gold? Explain your answer.
Suggest why so much trouble is taken to remove such a small amount of gold from the lead.
