Lead can be extracted from lead sulfide, PbS\text{PbS}PbS, in two stages.
Stage 1: Lead sulfide is heated in air. It reacts with oxygen to produce lead(II) oxide and sulfur dioxide.
Stage 2: The lead(II) 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 lead(II) oxide is heated with coke is:
2PbO+C→2Pb+CO2 2\text{PbO} + \text{C} \rightarrow 2\text{Pb} + \text{CO}_2 2PbO+C→2Pb+CO2State, with a reason, whether PbO\text{PbO}PbO is oxidised or reduced in this reaction.
Calculate the minimum mass, in tonnes, of coke needed to react with 66.96 tonnes66.96\text{ tonnes}66.96 tonnes of lead(II) oxide. [1 tonne=106 g1\text{ tonne} = 10^6\text{ g}1 tonne=106 g; relative atomic masses: Ar(Pb)=207.2A_r(\text{Pb}) = 207.2Ar(Pb)=207.2, Ar(O)=16.0A_r(\text{O}) = 16.0Ar(O)=16.0, Ar(C)=12.0A_r(\text{C}) = 12.0Ar(C)=12.0]
The molten lead obtained from some blast furnaces contains 0.3%0.3\%0.3% silver dissolved as an impurity.
The silver is removed by:
Use the information above to answer the following questions:
What can you deduce about the relative solubility of silver in zinc and in lead?
What can you deduce about the melting point of the mixture of zinc and silver?
What can you deduce about the boiling point of zinc compared to that of silver? Explain your answer.
Suggest why so much trouble is taken to remove such a small amount of silver from the lead.
