Unit 12: Nitrogen & Sulfur

Nitrogen
> d__; main component in a__
> very u__ bc no p__ + very s__ __ bond

diatomic, air, unreactive, polarity, strong triple

Ammonia
> acts as Brønsted–Lowry base by __ protons: NH₃(aq) + H⁺(aq) → __(aq)
> in H₂O: NH₃(aq) + H₂O(l) ←→ N__(aq) + __(aq) ;; very s__ as both NH₃ & H₂O are p__ & form _ bonds
> equilibrium lies to the __ thus w__ base

accepting, NH4+, NH4+, OH-, soluble, polar, H, left, weak

NH₃(g) + acid → __ __
e.g. NH₃(g) + HNO₃(aq) → __(aq)

ammonium salt, NH4NO3

NH₃ from ammonium salts
> d__ when heated to original r__ (if (NH₄)₂, NH₄ remains on salt)
>> NH₄Cl(s) → N__(g) + __(g) ;; (NH₄)₂SO₄(s) → NH₃(g) + __(s)

> or w/ OH^-:
>> 2NH₄Cl(s) + Ca(OH)₂ → 2__(g) + __(s) + 2__(l)
>> thus u can test for NH₄⁺ w/ testing for __(g) (damp __ litmus paper → blue)

decomposes, reactants, NH3, HCl, NH4HSO4, NH3, CaCl2, H2O, NH3, red

Nitrogen oxides
> formed under e__ conditions:
>> naturally: l__ triggers N₂ + O₂ → __/NO₂
>> man-made: c__ e__ have high p__ & t__ ;; released via e__ pipes
> c__ c__ used to decr pollution from cars:
>> nitrogen oxide is r__ on s__ of h__ c__ e.g. Pt → N₂
>> 2CO(g) + 2NO(g) → 2__(g) + N₂(g)

extreme, lightning, NO, car engines, pressure, temp, exhaust, catalytic converter, reduced, surface, hot catalyst, CO2

Photochemical smog
Ø  Nitrogen oxides can react w/ substances in __ → s__ pollutants
Ø  Exhaust fumes also contain v__ o__ c__ (VOCs)
o   These are __ HCs from fuel & their o__ products
o    VOCs react w/ nitrogen oxides w/ __ → peroxyacetyl nitrate (__)
o   Is a photochemical reaction (needs UV)
o   PAN is found in p__ smog & affects l__ & e__ ;; in high concs, p__ life too

air, secondary, volatile organic compounds, unburnt, oxidised, sunlight, PAN, photochemical, lungs, eyes, plant

Primary pollutants
> __ __
> __

nitrogen oxides, VOCs

Secondary pollutants
> __
> p__ from n__ o__ w/ s__ in a__

PAN, products, nitrogen oxides, substances, air

Acid rain
> when l__ strikes: 2__(g) + O₂(g) ←→ 2__(g)
> air also has __ & tiny w__ d__ that make up c__
> __ dissolves & reacts w/ O₂: 4__(aq) + 2__(l) + __(g) → 4__(aq)
> clouds r__ = less t__ = larger d__
>> when h__ enough, droplets w/ ts dil. HNO₃ fall as acid rain
> SO₂ can also o__ → __ & then react w/ r__:
>> SO₃(g) + __(l) → __(aq)

lightning, NO, NO2, O2, water droplets, clouds, NO2, NO2, H2O, O2, HNO3, rise, temp, droplets, high, oxidise, SO3, rainwater, H2O, H2SO4

Catalysts
> NO₂ catalyses o__ of S__ → S__ (for H₂SO₄ acid rain):
>> NO₂(g) + __(g) → SO₃(g) + __(g)
> __ (above) oxidises → NO₂ (for regeneration of SO₂):
>> __(g) + 1/2__(g) → __(g)
>> this NO₂ oxidises another SO₂, repeating this process

oxidation, SO2, SO3, SO2, NO, NO, NO, O2, NO2