IB Chemistry HL R2.1 How much? The amount of chemical change questions

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Question 1

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A process makes ethanol using the balanced reaction $\mathrm{C_2H_5Br + NaOH \rightarrow C_2H_5OH + NaBr}$ Which proposed change would increase the atom economy, rather than only the percentage yield?

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Answer: C. Atom economy is set by the balanced equation and compares the mass of desired product with the total reactant mass. A pathway that incorporates a greater proportion of reactant mass into ethanol therefore has greater atom economy.
A: recovering more ethanol increases the experimental yield, not the atom economy.
B: reducing unreacted bromoethane changes conversion, while the reaction stoichiometry remains unchanged.
D: a catalyst changes the reaction rate, not the stoichiometric mass fraction forming ethanol.
Remember: atom economy depends on the reaction equation; percentage yield depends on the amount actually obtained.

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