19.6 NOx role in air pollution · @everexams.com

19.6 Role of oxides of nitrogen in spreading air pollution

⚡ primary pollutants → secondary · NOx chemistry · acid rain · health impact

🌩️ Natural & man-made NOx

Natural: Lightning fixes N2 + O2 → NO.
N2 + O2 (electric arc) → 2NO
2NO + O2 → 2NO2

Man-made: vehicle combustion, power plants, fertilizers, agriculture. Heavy traffic + industry = NOx + VOCs.

💡 MEMORY: LIGHTning makes LIGHT oxide (NO).

☀️ Secondary pollutants (PAN, ozone)

UV light + NOx + VOCs → secondary pollutants:

NOx + VOCs + sunlight → O3 + aldehydes + PAN (peroxyacetyl nitrate)

PAN is toxic, ozone is lung irritant.

📘 TIP: “PAN” = PeroxyAcyl Nitrate (smog ingredient).

💧 Acid rain formation

NO2 reacts with water:

2NO2 + H2O → HNO3 + HNO2 (nitric + nitrous acid)

NOx catalyst role: converts SO2 → H2SO4

2SO2 + O2 —(NOx)→ 2SO3
SO3 + H2O → H2SO4

Acid rain pH < 5.6, damages ecosystems, corrodes materials.

🧬 Health & environment

Harmful effects of NOx: respiratory illness, asthma, lung damage.
Global toll: ~7–8 million deaths/year (air pollution). Children especially vulnerable.

NOx also helps form fine particles and ground-level ozone.

⚠️ interesting: air pollution is significant child health risk.

📌 student guidelines & memorization

✓ Write the lightning reaction daily: N2 + O2 → 2NO ; then 2NO + O2 → 2NO2.

✓ Remember acronym: N.A.S. — Nitrogen oxides, Acid rain, Secondary pollutants (PAN, O3).

✓ Link sources: vehicles (NOx) + power plants + agriculture.

✓ Acid rain pH threshold: 5.6 (normal rain), acid rain below that.

✓ NOx acts as catalyst for SO2 → SO3 → H2SO4. “NO helps SO2 die (oxidize)”.

📅 lesson planner · @everexams.com

🔹 Day 1 – Sources & basic NOx reactions (natural + man‑made)
🔹 Day 2 – Photochemical smog: ozone, PAN, aldehydes
🔹 Day 3 – Acid rain (NO2 + water, catalysis of SO2)
🔹 Day 4 – Health effects, environment & practice MCQs

🧪 10 MCQs · oxides of nitrogen & pollution

Click an option: correct turns green, wrong turns red. Submit to see score & full key.

Score: —/10
🔑 answer key: (will appear after submit)