A factory manager is comparing the following reactions for manufacturing zinc oxide. (Relative atomic masses: Zn = 65, C = 12, O = 16)
Route A: ZnCO3→ZnO+CO2\mathrm{ZnCO_{3} \rightarrow ZnO + CO_{2}}ZnCO3→ZnO+CO2
Route B: 2Zn+O2→2ZnO\mathrm{2Zn + O_{2} \rightarrow 2ZnO}2Zn+O2→2ZnO
Calculate the atom economy for zinc oxide in Route A.
Route A gives a higher percentage yield than Route B. The manager says this means Route A must be the better choice. Explain why the percentage yields alone are not enough to support this decision.
151 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.