Oxides of Nitrogen (named) — Smog and Acid

NOx = nitrogen oxides (NO, NO₂ named). Smog link: NOx + sunlight / other pollutants → photochemical smog (school story). Acid link: NOx → nitric acid contribution to acid deposition; SOx (SO₂/SO₃) → sulphuric acid rain. Not CO₂: carbon dioxide is a greenhouse gas story — it is not taught as the main acid-rain oxide here.

Oxides of nitrogen matter environmentally even though air is mostly inert N₂. Named oxides. School lists focus on NO (nitrogen monoxide) and NO₂ (nitrogen dioxide), grouped as NOx. They form when air nitrogen and oxygen react in hot engines and furnaces. Smog. In sunlight, NOx take part in photochemical reactions with volatile organics (VOCs in wider air chapters) to build photochemical smog — brownish, eye-irritating polluted air in the school description. Acid deposition. NOx can form nitric acid in the atmosphere; sulphur oxides form sulphuric acid. Together SOx and NOx explain acid rain / acid deposition damaging lakes, soils, and buildings in the school narrative. CO₂ trap. Students often blame CO₂ for acid rain because it dissolves to make weak carbonic acid. Exam answers for acid rain must centre strong acids from SO₂/NOx, not CO₂ as the main cause. Keep Haber fertiliser pride separate from unwanted NOx pollution — same element, different compounds and contexts.

NOx means nitrogen oxides like NO and NO₂. They help make photochemical smog. They also help make acid rain (nitric acid), with sulphur oxides making sulphuric acid. Do not say CO₂ is the main acid-rain cause.

Name NO and NO₂ under NOx. Link combustion engines to formation. Write two harm lines: smog and nitric-acid deposition. Pair with SO₂/SO₃ → H₂SO₄ for the full acid-rain picture. Explicitly reject CO₂ as the primary acid-rain oxide in school marking.

Distinguish photochemical smog (NOx-driven, sunlight) from classical smoke-fog ideas if the syllabus contrasts them. State acid deposition includes wet rain and dry deposition of acidic gases. In 4-mark answers, give both sulphuric (from SOx) and nitric (from NOx) contributions and one clear “not CO₂” sentence.

NOx (NO, NO₂) → smog + nitric acid rain. SOx → sulphuric acid rain. Acid rain ≠ mainly CO₂.