Tungsten is a high-strength transition metal widely used in rocket engine nozzles and incandescent filaments due to its extremely high melting point.
Tungsten can be industrially obtained by reducing tungsten(VI) oxide with hydrogen gas at high temperatures:
WO3+3H2→W+3H2O \text{WO}_3 + 3\text{H}_2 \rightarrow \text{W} + 3\text{H}_2\text{O} WO3+3H2→W+3H2OCalculate the percentage atom economy for the production of tungsten, W\text{W}W, in this reaction.
(relative atomic masses: H=1.0\text{H} = 1.0H=1.0, O=16.0\text{O} = 16.0O=16.0, W=183.8\text{W} = 183.8W=183.8
relative formula masses: H2=2.0\text{H}_2 = 2.0H2=2.0, WO3=231.8\text{WO}_3 = 231.8WO3=231.8)
Give your answer to two significant figures.
157 exam-style questions on Edexcel GCSE Chemistry 6.2 Quantitative analysis, covering 6.2.1 Concentration in mol dm⁻³ and titration calculations, 6.2.2 Percentage yield and why actual yield falls short, 6.2.3 Atom economy of a reaction, 6.2.4 Choosing a reaction pathway, and 6.2.5 Molar volume of gases and Avogadro's law. Each one has a worked solution and a mark scheme showing where the marks go.