Ethanol can be made by two routes.
| Route 1: fermentation | Route 2: hydration of ethene | |
|---|---|---|
| Equation | C6H12O6→2C2H5OH+2CO2\mathrm{C_{6}H_{12}O_{6} \rightarrow 2C_{2}H_{5}OH + 2CO_{2}}C6H12O6→2C2H5OH+2CO2 | C2H4+H2O⇌C2H5OH\mathrm{C_{2}H_{4} + H_{2}O \rightleftharpoons C_{2}H_{5}OH}C2H4+H2O⇌C2H5OH |
| Atom economy | 51% | 100% |
| Conditions | 30 ∘C30\,^\circ\mathrm{C}30∘C, 1 atm, yeast | 300 ∘C300\,^\circ\mathrm{C}300∘C, 60 atm, catalyst |
| Conversion | slow batch process | about 5% per pass; unreacted ethene recycled |
| Raw material | sugar from crops | ethene from crude oil |
Statement 1: Route 2 wastes fewer of the reactant atoms as by-products
Statement 2: Route 2's low conversion per pass means its atom economy is really lower than Route 1's
Statement 3: Route 2's high temperature and pressure increase its energy costs
Which statements are correct?
1 only
2 and 3 only
1, 2 and 3
1 and 3 only
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.