Titanium is a highly valued transition metal used in aerospace engineering due to its low strength-to-weight ratio and high corrosion resistance. It is extracted from its ore, rutile (TiO2\text{TiO}_2TiO2), via a two-step process. In the second step, titanium(IV) chloride (TiCl4\text{TiCl}_4TiCl4) is reduced by heating with molten magnesium at approximately 1000 ∘C1000\,^\circ\text{C}1000∘C in an inert argon atmosphere:
TiCl4(g)+2Mg(l)→Ti(s)+2MgCl2(l) \text{TiCl}_4(\text{g}) + 2\text{Mg}(\text{l}) \rightarrow \text{Ti}(\text{s}) + 2\text{MgCl}_2(\text{l}) TiCl4(g)+2Mg(l)→Ti(s)+2MgCl2(l)Which statement correctly describes the chemical roles or oxidation state changes occurring during this extraction process?
TiCl4\text{TiCl}_4TiCl4 acts as the reducing agent because the oxidation state of titanium decreases from +4+4+4 to 000.
Titanium is reduced because the oxidation state of the titanium species changes from +4+4+4 in TiCl4\text{TiCl}_4TiCl4 to 000 in Ti\text{Ti}Ti.
Carbon cannot be used as an alternative reducing agent because carbon is less reactive than titanium.
Magnesium acts as the oxidising agent because its oxidation state increases from 000 in Mg\text{Mg}Mg to +2+2+2 in MgCl2\text{MgCl}_2MgCl2.
110 exam-style questions on Edexcel GCSE Chemistry 5.1 Obtaining and using metals, covering 5.1.1 The reactivity series of metals, 5.1.2 Displacement reactions as redox reactions, 5.1.3 Extracting metals from ores by reduction, 5.1.4 Biological methods of metal extraction, 5.1.5 Resistance to oxidation and recycling metals, and 5.1.6 Life cycle assessment. Each one has a worked solution and a mark scheme showing where the marks go.