To improve the sustainability of an industrial synthesis of Compound ZZZ (Mr=200 g mol−1M_r = 200\text{ g mol}^{-1}Mr=200 g mol−1), chemical engineers compare two proposed manufacturing pathways:
Route P: Reactant A (Mr=100)+Reactant B (Mr=150)→Compound Z (Mr=200)+By-product C (Mr=50) \text{Route P: } \text{Reactant A } (M_r = 100) + \text{Reactant B } (M_r = 150) \rightarrow \text{Compound Z } (M_r = 200) + \text{By-product C } (M_r = 50) Route P: Reactant A (Mr=100)+Reactant B (Mr=150)→Compound Z (Mr=200)+By-product C (Mr=50)This process achieves a 70.0% percentage yield.
Route Q: Reactant D (Mr=120)+Reactant E (Mr=100)→Compound Z (Mr=200)+By-product F (Mr=20) \text{Route Q: } \text{Reactant D } (M_r = 120) + \text{Reactant E } (M_r = 100) \rightarrow \text{Compound Z } (M_r = 200) + \text{By-product F } (M_r = 20) Route Q: Reactant D (Mr=120)+Reactant E (Mr=100)→Compound Z (Mr=200)+By-product F (Mr=20)This process achieves an 85.0% percentage yield.
Assume reactants are supplied in exact stoichiometric ratios.
Which of the following statements correctly compares the atom economy and the reaction mass efficiency (RME) of Route Q relative to Route P? (Note: Reaction Mass Efficiency=Atom Economy×Percentage Yield\text{Reaction Mass Efficiency} = \text{Atom Economy} \times \text{Percentage Yield}Reaction Mass Efficiency=Atom Economy×Percentage Yield)
Route Q has an atom economy that is 10.9%10.9\%10.9% higher and a reaction mass efficiency that is 21.3%21.3\%21.3% higher than Route P.
Route Q has an atom economy that is 10.9%10.9\%10.9% higher, but a reaction mass efficiency that is 15.0%15.0\%15.0% lower than Route P.
Route Q has an atom economy that is 16.7%16.7\%16.7% higher and a reaction mass efficiency that is 24.2%24.2\%24.2% higher than Route P.
Route Q has an atom economy that is 10.9%10.9\%10.9% higher, but both routes have the same reaction mass efficiency of 56.0%56.0\%56.0%.
81 exam-style questions on OCR GCSE Chemistry Improving processes and products. Each one has a worked solution and a mark scheme showing where the marks go.