Chemistry 0620 · IGCSE · Extraction of metals

Extraction of metals — practice question

Titanium is extracted from the ore rutile. Rutile is an impure form of titanium(IV) oxide, $\text{TiO}_2$.
(a)[2]

(i) Suggest the name of the method used to separate liquid titanium(IV) chloride from the liquid impurities. (ii) Carbon monoxide, $\text{CO}(g)$, is produced in the reaction as well. Why must carbon monoxide not be allowed to enter the atmosphere?

(b)[4]

Calculate $M_r$ for $\text{TiO}_2$. Calculate how many moles are present in 400 g of $\text{TiO}_2$. Determine the number of moles of $\text{Cl}_2$ that react with 400 g of $\text{TiO}_2$. Calculate the volume of $\text{Cl}_2$ that reacts with 400 g of $\text{TiO}_2$.

(c)[3]

(i) Balance the chemical equation for the reaction. $\text{TiCl}_4 + \ldots\text{Mg} \rightarrow \text{Ti} + \ldots\text{MgCl}_2$ (ii) Titanium(IV) chloride can also be reacted with sodium rather than magnesium. Write a chemical equation for the reaction between titanium(IV) chloride and sodium. (iii) Suggest why the reaction between titanium(IV) chloride and magnesium is carried out in an atmosphere of argon instead of air.

(d)[5]

(i) Give two observations and write a chemical equation for the reaction that occurs when dilute hydrochloric acid reacts with magnesium. (ii) Name the process used to separate the titanium from the mixture after all the magnesium has been removed. (iii) Suggest why titanium does not react with dilute hydrochloric acid.

(e)[2]

(i) Name the product formed at the negative electrode (cathode) during the electrolysis of aqueous magnesium chloride. (ii) Suggest how magnesium can be produced from magnesium chloride by electrolysis.

Worked solution & mark scheme

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