Zirconium is extracted from its main ore, zirconia (ZrO2\text{ZrO}_2ZrO2), in a three-stage process.
Stage 1: Zirconia is heated with chlorine and coke (carbon) at a temperature of about 900 ∘C900\ ^\circ\text{C}900 ∘C.
ZrO2+2Cl2+2C→ZrCl4+2CO \text{ZrO}_2 + 2\text{Cl}_2 + 2\text{C} \rightarrow \text{ZrCl}_4 + 2\text{CO} ZrO2+2Cl2+2C→ZrCl4+2COStage 2: Zirconium tetrachloride (ZrCl4\text{ZrCl}_4ZrCl4) is then added to liquid magnesium at a temperature of about 800 ∘C800\ ^\circ\text{C}800 ∘C in an atmosphere of argon.
ZrCl4+2Mg→Zr+2MgCl2 \text{ZrCl}_4 + 2\text{Mg} \rightarrow \text{Zr} + 2\text{MgCl}_2 ZrCl4+2Mg→Zr+2MgCl2During the reaction, the temperature rises to about 1100 ∘C1100\ ^\circ\text{C}1100 ∘C.
Stage 3: The magnesium chloride is removed by distillation from the mixture formed in stage 2, leaving behind pure zirconium.
In stage 1, is the carbon oxidised or reduced? Give a reason for your answer.
What does the reaction in stage 2 indicate about the reactivity of magnesium compared to the reactivity of zirconium? Explain your answer.
In stage 3, suggest why distillation can be used to remove magnesium chloride from zirconium.
Zirconium has these properties:
Complete the table below to suggest an important property of zirconium for each use. Choose from the four properties listed above. You must choose a different property for each use.
| Use | Property |
|---|---|
| cladding for nuclear fuel rods | |
| dental implants and crowns | |
| piping for highly corrosive acids |
