Flashcards · 9701 · AS Topic 12

Nitrogen and sulfur (AS Level) flashcards

7 cards on AS Topic 12. Pick a subtopic or study them all.

Study mode needs JavaScript. Every card is listed below, so you can still cover the answers and test yourself.

All 7 cards

For a quick read-through or printing. Cover the right-hand side to test yourself.

Two reasons nitrogen gas is unreactive: The N≡N triple bond has a very high bond enthalpy, so the activation energy is large; and the molecule is non-polar, so it does not attract nucleophiles or electrophiles.
Why is ammonia a base?: The lone pair on nitrogen accepts a proton, forming a dative bond: NH₃ + H⁺ → NH₄⁺. In water: NH₃ + H₂O ⇌ NH₄⁺ + OH⁻ (weak base).
Shape and bond angle of NH₃ and of NH₄⁺: NH₃: trigonal pyramidal, 107° (one lone pair). NH₄⁺: tetrahedral, 109.5° (the lone pair is now a bonding pair; all four N–H bonds are identical).
How is ammonia displaced from an ammonium salt, and how is it detected?: Warm with NaOH(aq): NH₄Cl + NaOH → NaCl + NH₃ + H₂O. Ammonia turns damp red litmus blue.
Show that NO catalyses the oxidation of SO₂ in the atmosphere: NO + ½O₂ → NO₂ NO₂ + SO₂ → SO₃ + NO NO is regenerated unchanged.
How do oxides of nitrogen form, and how are they removed from car exhausts?: N₂ + O₂ → 2NO at high temperature in engines (and from lightning). Catalytic converter: 2CO + 2NO → 2CO₂ + N₂.
Photochemical smog: NO and NO₂ react with unburned hydrocarbons in sunlight to form peroxyacetyl nitrate (PAN), an eye and lung irritant.