NON-METALS
Hydrogen
Reactions producing hydrogen
Reactive metals + water:
reactive metals (K - Mg) react w/ water to produce H₂
Metals + acids:
metals (^H) + dilutes acids
Electrolysis of aqueous sol:
electrolysis of solutions- if cation in sol is ^H
Methane + steam:
CH₄ + H₂O > CO + 3H₂

Uses of hydrogen:
make NH₃, margarine (unsaturated veg oil + H₂ >(Ni)> margarine), fuel for rockets

Uses of water: Industry- soft drinks, chemicals, drugs
Home- drinking, cooking, washing

Purification of water

Sedimentation- suspended solids settle out of water > sediment deposited by gravity
Flocculation- lime & alum added to raw water > tiny suspended particles stick together > larger particles/clumps = flocs (v.fine fluffy mass)
Filtration- after flocculation, suspended matter (large, fine) removed from water (using medium permeable to water but not material)
Sterilisation- chlorine added to water to kill (remove) bact

Test
Hydrogen
-pop test: 2H₂ + O₂ > 2H₂O
Water:
-hydration of anhydrous CuSO₄ crystals (white/ pale green solid > blue), -cobalt paper: blue > pink

Oxygen
Uses:
Respiration
-combustion of sugars in body cells
  glucose + O₂ > CO₂ + H₂O + energy
Combustion
-subs + O₂ > energy
Rusting
-slow oxidation of Fe in presence of oxygen & moisture to Fe₂O₃
(brown solid)
  4Fe + 3O₂ > (H₂O) > 2Fe₂O₃

Methods of rust prevention
-prevent water & oxygen from reaching Fe or steel: cover w/ paint, oil/ grease, tin, chromium
-galvanise w/ zinc: sacrificial protection, zinc corrodes 1st > oxide layer
-stainless steel: Cr or Ni added to Fe

Test
-make burning splint burn brightly, rekindles a glowing splint

Uses of oxygen
-bottled oxygen assists ppl breathing difficulties, -space shuttles, fuel, -make steel O₂ passed over Fe > burns off impurities, -oxy-acetylene torch: acetylene gases (hydrocarbons) & O₂ mixed > weld iron & steel

Volume composition of air
N₂: 79%, O₂: 20%, noble gases (mainly argon) <1%, CO₂: 0.03%, water vapour: variable

Air pollution: harmful subs- CO, SO₂, oxides of N, Pb compounds and CFC's

Sources of air pollutants
CO: poisonous gas formed in incomplete combustion of fuels, causes headaches, heart damage
SO₂: combustion of fuels in fuels in power stations, oil refineries and extraction of metals in industries, causes breathing difficulties > bronchitis & lung cancer, acid rain (SO₂ + H₂O > H₂SO₃- sulphurous acid)
NO_X: combustion of fuels in motor vehicles and industries, damages lungs, acid rain (NO₂ + H₂O > - nitrous acid)
Pb compounds: combustion of leaded petrol, causes brain damage, affects heart kidneys
CFC: from aerosol s, coolants in refrigerators, thins ozone layer > allows UV rays to penetrate atmosphere > skin cancer

O₂ & N₂ obtained from fractional distillation of liquid air

Nitrogen
unreactive gas, important elements in plants & animals, used in amide linkage of proteins

Haber process

N₂ + 3H₂ 2NH₃ + E
Pressure: 200 atm (speed up rate of reaction), temp 450°C (too high: reverse reaction favoured, too low: too slow), catalyst: Fe
NH₃ removed when reaction 15% complete as at equilibrium under the conditions only 15% of reaction is completed
Ammonia produced: heat ammonium compounds (w/ bases)

N (make proteins), P, K important in quick & healthy plant growth, need to be water soluble to be included in fertilisers (NH₃ + acid sol > solid which is crystallised from solution- NH₃ + HNO₃ > NH₄NO₃, NH₃ + H₂SO₄ > (NH₄)₂SO₄)

Sulphur
S: gun-powder, S burns > SO₂, uses of SO₂: bleach (in manufacture of paper), food preservative (kill bact), make H²SO₄
Contact Method
-the method of producing H₂SO₄ make SO₂:   S + O₂ > SO₂
make SO₃:   2SO₂ +O₂ <-> 2SO₃ + E (2-3 atm, 450C, catalyst: vanadium(V) oxide: V₂O₅)
dissolve SO₃ in H₂SO₄:   SO₃ + H₂SO₄ > H₂S₂O₇
(difficult & dangerous to dissolve directly in water > 96% H₂SO₄ used)
dilute H₂S₂O₇ to make conc H₂SO₄:   H₂S₂O₇ + H₂O > 2 H₂SO₄
H₂SO₄: strong acid: reacts w/ bases, metals, carbonates, conc H₂SO₄ used as dehydrating agent and oxidising agent, H₂SO₄: used in making fertilisers, detergents, plastics, synthetic fibres, paints, dyes (SO₂: reducin