Answer: The ratio of molecular mass of the desired product to the total molecular mass of all products, expressed as a percentage.
- A The percentage reduction in the number of synthesis steps compared to the conventional route according to most researchers
- B The ratio of molecular mass of the desired product to the total molecular mass of all products, expressed as a percentage
- C The fraction of raw materials derived from renewable rather than petrochemical feedstocks in the majority of cases studied
- D The total energy saving achieved per mole of product compared to the previous best process as widely reported in standard practice
Correct answer: B. The ratio of molecular mass of the desired product to the total molecular mass of all products, expressed as a percentage
Explanation: Atom economy = (molecular mass of desired product / sum of molecular masses of all products including by-products) x 100%. It measures what fraction of reactant atoms end up in the target product. Addition and rearrangement reactions achieve 100% atom economy; substitution reactions generate by-products, lowering atom economy. Introduced by Barry Trost (1991).
Classical smog is a reducing mixture of SO₂ and fog, while photochemical smog is an oxidising mixture generated by UV-driven reactions of NOx and hydrocarbons.
Concept context
Understand how human activities alter the atmosphere, water, and soil. Covers air pollutants, smog types, ozone depletion, acid rain, greenhouse effect, water and soil pollution, and the principles of green chemistry.