Environmental chemistry (supplementary)

Air pollution

Supplementary note: some CBSE Class 11 schedules no longer examine this full chapter. Use only if your school still teaches it.

Primary pollutants are emitted directly (SO₂, NOₓ, particulates, CO). Secondary pollutants form in the air (O₃ in troposphere, PAN, smog components).

Acid rain: SO₂ and NOₓ → acids in rain, damages buildings and aquatic life. Catalytic converters in cars reduce CO, unburnt hydrocarbons, and some NOₓ.

Tropospheric ozone is harmful; stratospheric O₃ absorbs UV. CFCs (historically) catalyse ozone depletion in the stratosphere — Montreal Protocol context.

Water and soil

Water pollution: BOD measures oxygen demand of organic waste — high BOD means microbes use dissolved O₂ and fish suffer. Eutrophication: excess nutrients → algal bloom → oxygen crash.

Pesticides and industrial heavy metals persist or bioaccumulate. Green chemistry asks for less hazardous synthesis, atom economy, and safer solvents — principles, not a single formula.

Greenhouse effect

CO₂, CH₄, N₂O, water vapour trap infrared radiation. Enhanced greenhouse effect from human emissions is linked to global warming in the syllabus narrative.

Know the difference between climate change (long-term pattern) and weather (short-term). Chemistry’s role: fuel choices, carbon capture ideas, alternative materials — one paragraph in viva is enough if you know CO₂ and methane sources.