Tungsten is a transition metal widely used in industrial applications, such as the manufacture of electrical filaments and wear-resistant alloys. It can be extracted from tungsten(VI) oxide (WO3\text{WO}_3WO3) using different reducing agents.
Which chemical process is the most sustainable in terms of the atom economy of the tungsten produced?
Use the following relative atomic masses: Ar(H)=1.0,Ar(C)=12.0,Ar(O)=16.0,Ar(Ca)=40.1,Ar(W)=183.8A_r(\text{H}) = 1.0, \quad A_r(\text{C}) = 12.0, \quad A_r(\text{O}) = 16.0, \quad A_r(\text{Ca}) = 40.1, \quad A_r(\text{W}) = 183.8Ar(H)=1.0,Ar(C)=12.0,Ar(O)=16.0,Ar(Ca)=40.1,Ar(W)=183.8
WO3+3CO→W+3CO2\text{WO}_3 + 3\text{CO} \rightarrow \text{W} + 3\text{CO}_2WO3+3CO→W+3CO2
WO3+3C→W+3CO\text{WO}_3 + 3\text{C} \rightarrow \text{W} + 3\text{CO}WO3+3C→W+3CO
WO3+3Ca→W+3CaO\text{WO}_3 + 3\text{Ca} \rightarrow \text{W} + 3\text{CaO}WO3+3Ca→W+3CaO
WO3+3H2→W+3H2O\text{WO}_3 + 3\text{H}_2 \rightarrow \text{W} + 3\text{H}_2\text{O}WO3+3H2→W+3H2O
199 exam-style questions on OCR A A Level Chemistry Atoms and reactions, covering Atomic structure and isotopes, Compounds, formulae and equations, Amount of substance, Acids, and Redox. Each one has a worked solution and a mark scheme showing where the marks go.