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European Baccalaureate Chemistry study materials
European Baccalaureate Chemistry study resources

European Baccalaureate Chemistry: Chemistry in context: environment, materials, industry

European Baccalaureate Chemistry · Work through your exam, one topic at a time.

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Chemistry in context: environment, materials, industry

Chemistry in context applies core principles to the environment, materials and industry. The exam tests your ability to evaluate processes using atom economy, energy, waste and sustainability, and to explain environmental chemistry accurately.

Core rules

  • Greenhouse gases absorb infrared radiation and warm the atmosphere; the main anthropogenic gases are CO2, CH4, N2O and fluorinated gases. Ozone depletion by CFCs is a separate problem involving chlorine radicals in the stratosphere.
  • Acid rain arises from SO2 and NOx, which form sulfurous/sulfuric and nitric acids; controls include flue-gas desulfurisation, low-sulfur fuels and catalytic converters.
  • Photochemical smog forms when NOx and volatile organic compounds react in sunlight, producing ozone and peroxyacetyl nitrate (PAN) at ground level.
  • Industrial catalysis: Haber process (Fe, high pressure, moderate temperature) for ammonia; Contact process (V2O5) for sulfuric acid; catalytic converters (Pt/Pd/Rh) oxidise CO and hydrocarbons and reduce NOx.
  • Green chemistry seeks high atom economy, low toxicity, renewable feedstocks, energy efficiency and minimal waste. Atom economy = (molar mass of desired product / total molar mass of reactants) × 100.
  • Materials: alloys are mixtures of metals; polymers are addition or condensation; ceramics and composites have tailored properties. Recycling and life-cycle analysis reduce environmental impact.

Worked example

Compare the atom economy of ethanol production by ethene hydration and by glucose fermentation. Hydration: C2H4 + H2O → C2H5OH. All reactant atoms appear in the product, so atom economy = 100%. Fermentation: C6H12O6 → 2C2H5OH + 2CO2. M(C6H12O6) = 180 g mol−1; M(2C2H5OH) = 92 g mol−1. Atom economy = 92/180 × 100 = 51.1%. Fermentation has a lower atom economy because CO2 is a by-product, although it uses a renewable feedstock.

Traps that cost marks

  • Confusing atom economy with percentage yield; atom economy is theoretical and ignores losses.
  • Claiming catalytic converters eliminate CO2; they mainly convert CO, hydrocarbons and NOx.
  • Mixing up the greenhouse effect and ozone depletion; CFCs are not the main greenhouse gases.
  • Forgetting that a catalyst does not change the equilibrium yield, only the rate.
  • Describing a polymer as biodegradable without distinguishing compostable, degradable and recyclable.