Chemistry in Society: Environment, Industry, Materials and Everyday Life
What you must understand
Environment: greenhouse gases (CO₂, CH₄, N₂O), acid rain (SO₂, NOₓ forming H₂SO₄/HNO₃), ozone depletion (CFCs), photochemical smog, water pollution and eutrophication. Know sources, effects and mitigation (catalytic converters, scrubbers, renewable energy, recycling).
Industry: Haber process (NH₃), contact process (H₂SO₄), Ostwald process (HNO₃), chlor-alkali, blast furnace (iron), cement, glass, paper. Know conditions, catalysts and key reactions. Understand raw materials, energy demands and environmental impact.
Materials: alloys (steel, brass, bronze), polymers (addition vs condensation, thermoplastics vs thermosets), ceramics, composites, and their properties and uses. Everyday chemistry: soaps and detergents, fertilisers (NPK), food additives, pharmaceuticals, fuels (fossil vs renewable).
Traps
Don't confuse the greenhouse effect with ozone depletion - different gases and mechanisms. Catalytic converters reduce CO, NOₓ and hydrocarbons, not CO₂. Know which process produces which product (contact → H₂SO₄, not HNO₃).
Rule of thumb
Match pollutant to source and remedy: SO₂ from fossil fuels → scrubbers/lime; NOₓ from engines → catalytic converters.
Worked example
Haber process: N₂ + 3H₂ ⇌ 2NH₃, iron catalyst, ~450 °C, high pressure; higher pressure favours ammonia (fewer gas moles).