Nitrogen in the Air and in Compounds — Compounds

Nitrogen compounds (school set): NH₃ · HNO₃ · NOx (NO, NO₂ named) · nitrates (NO₃⁻). Sulphur compounds (school set): SO₂ · SO₃ · H₂SO₄ · sulfates / sulphates (SO₄²⁻). Roles at a glance: NH₃ / nitrates → fertilisers; HNO₃ / H₂SO₄ → strong acids; NOx / SO₂ → pollution & acid deposition pathways.

Compounds are where N and S do most of their exam work. Nitrogen side. Ammonia NH₃ is the Haber product and a fertiliser feedstock. Nitric acid HNO₃ comes via Ostwald chemistry and forms nitrate salts. NOx means the named nitrogen oxides (especially NO and NO₂) that appear in combustion and smog stories. Nitrates (NO₃⁻) are the combined-nitrogen fertiliser ions. Sulphur side. Burning sulphur or sulphur compounds gives SO₂. Further oxidation gives SO₃. SO₃ / water chemistry leads to sulphuric acid H₂SO₄ (Contact Process industrially; also the acid-rain school path). Sulfate (sulphate) salts contain SO₄²⁻. Keep the map tidy. Air N₂ is elemental; NH₃ and HNO₃ are useful industrials; NOx and SO₂ are pollutant oxides; H₂SO₄ and nitrates/sulfates are acids and salts. Do not call SO₂ “nitric acid” or NH₃ “a nitrogen oxide.” Exam cue: list formulas correctly and state one role each when asked to “name important compounds of nitrogen and sulphur.”

Remember these formulas: NH₃, HNO₃, NOx, SO₂, SO₃, H₂SO₄, nitrates, sulfates. NH₃ and nitrates help fertilisers. SO₂ / SO₃ link to sulphuric acid and acid rain. NOx are nitrogen oxides in air pollution stories.

Sort by element: N-compounds (NH₃, HNO₃, NOx, NO₃⁻) vs S-compounds (SO₂, SO₃, H₂SO₄, SO₄²⁻). Add one use or harm line for each group: fertilisers/acids vs smog/acid rain. Spell sulphate/sulfate consistently with your board’s spelling.

In classification answers, separate industrial useful compounds (NH₃, HNO₃, H₂SO₄, fertiliser salts) from atmospheric pollutant oxides (NOx, SO₂) that form acids outdoors. Note that SO₃ is both a Contact intermediate and an acid-rain intermediate. Avoid treating “NOx” as a single molecule — it is a family label for NO/NO₂ etc.

NH₃ · HNO₃ · NOx · nitrates. SO₂ · SO₃ · H₂SO₄ · sulfates. Fertiliser / acid / pollution roles.