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QLDChemistryQuick questions
Unit 4: Structure, synthesis and design
Quick questions on Green chemistry principles and atom economy (QCE Chemistry Unit 4)
15short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is the 12 principles of green chemistry?Show answer
The principles were formulated by Anastas and Warner in 1998 and remain the QCAA-cited reference. A condensed version sufficient for QCAA EA:
What is atom economy?Show answer
Atom economy is the central quantitative measure in green chemistry. It compares the mass of desired product to the total mass of reactants in a balanced equation.
What is atom economy vs percentage yield?Show answer
These are independent measures that students routinely conflate.
What is applying the principles?Show answer
Conventional petroleum diesel: high atom economy combustion but non-renewable feedstock (Principle 7 violation), high CO2 emissions (Principle 1 / 10), and energy-intensive refining (Principle 6).
What is limitations and trade-offs?Show answer
Green chemistry is rarely a free win. Trade-offs that EA marking guides expect students to acknowledge:
What is common traps?Show answer
Treating atom economy and percentage yield as interchangeable. They measure different things; QCAA marks separate them explicitly.
What is ethanol by hydration of ethene?Show answer
CH2=CH2 + H2O -> CH3CH2OH. Mr(ethanol) = 46. Mr(reactants) = 28 + 18 = 46.
What is ethanol by fermentation of glucose?Show answer
C6H12O6 -> 2 CH3CH2OH + 2 CO2. Mr(2 ethanol) = 92. Mr(glucose) = 180.
What is esterification of ethanoic acid with ethanol?Show answer
CH3COOH + CH3CH2OH -> CH3COOCH2CH3 + H2O. Mr(ester) = 88. Mr(reactants) = 60 + 46 = 106.
What is saponification of ethyl ethanoate with NaOH?Show answer
CH3COOCH2CH3 + NaOH -> CH3COONa + CH3CH2OH. Two products of comparable mass; if sodium ethanoate is the target, atom economy = 82 / 128 = 64 percent. If both products are desired (industry), atom economy is effectively 100 percent.
What is treating atom economy and percentage yield as interchangeable?Show answer
They measure different things; QCAA marks separate them explicitly.
What is adding atom economies across steps?Show answer
Atom economies multiply across consecutive reactions (not add), the same way yields do, if you are tracking the overall atom economy of a pathway. Most exam items ask only for a single-step atom economy.
What is ignoring by-products in the denominator?Show answer
Atom economy compares desired product to total mass; if you forget the eliminated water or CO2, the calculation comes out higher than the QCAA marking guide.
What is citing "it's biodegradable" as automatic green credentials?Show answer
Biodegradation is one principle of 12. A biodegradable polymer made with toxic monomers or in an energy-intensive process is not green overall.
What is forgetting Principle 2 in real questions?Show answer
Most QCAA evaluations of industrial processes have atom economy as the lead criterion. If you cite green chemistry without calculating atom economy, you have skipped the central metric.