Chemical Resources

Chemical Resources

1. Structure of the Earth

   • Lithosphere, crust & top of mantle
   • Earth's core transfers energy
     • Deeper = Hotter
   • Plate tectonic theory
     • Pangea: Old supercontinent
     • Explains wide range of evidence e.g. 'Puzzle Piece' atlas
     • Wegener's continental drift theory (1914) not initially accepted.
   • Magma + Rocks:
     • Iron-rich Basalt: Runny lava
     • Silica-rich Rhyolite: Viscous lava
       • Explosions!

2. Construction Materials

   • Hardness compared by rubbing rocks together
     • E.g. Granite > Marble > Limestone
       • Granite
         • Cooled Magma
         • Igneous
         • Interlocking Crystals
       • Marble
         • Metamorphic
         • Limestone changed by heat+pressure
         • Baked, therefore Marble>limestone
       • Limestone
         • Sedimentary - compressed and cemented sediment
   • Thermal Decomposition
     • One material heated --> 2+ new substances
     • Calcium Carbonate (Limestone):
       • CACO3 --> CaO + CO2
         • (Limestone) -->
         • (Calcium oxide + Carbon Diox.)
     • Cement = Limestone + Clay + HEAT
       • Concrete = Cement + Sand/Stones + Water
         • Reinforced concrete: Steel rods/mesh
           • Composite material: Both distinguishable
           • Concrete weak under tension
             • Steel stops stretching/cracking

3. Metals + Alloys

   • Alloys
     • Mixtures containing 2+ metals
     • Amalgam (Mercury): Fillings
     • Brass (Copper + Zinc)
     • Solder (Lead + Tin)
     • Smart alloys - Retain shape when heated
       • E.g. Glasses frames of Nititol (Nickel-Titanium)
   • Extracting Copper (Electrolysis)
     • Advantages:
       • Low melting point, little energy
       • Reduces mining
       • Reduces copper cost
     • Disadvantages:
       • Small amounts in electrical equipment
         • Difficult to separate
       • Pure and impure cannot be mixed (e.g. Solder)
       • Fewer mining jobs
       • May produce pollution
     • Pure Cathode (-)
       • Gains mass
       • Cu(2+) Ions + 2e- --> Cu atoms
     • Impure Anode (+)
       • Loses mass
       • Drops impurities
       • Cu atoms --> Cu(2+) +2e-

4. Making Cars

   • Rusting
     • Iron and Steel rust: Other metals corrode
     • Acid rain + Salt water accelerate
     • Is Oxidation:
       • Iron + Oxygen + Water --> Hydrated Iron (III) Oxide
   • Materials used:
     • Aluminium: lightweight, malleable, no corrosion
     • Iron/Steel: Malleable, strong
     • Plastics: No corrosion, cheap
   • Alloys - More useful properties than original metals
     • Steel stronger than iron
     • Steel less likely to corrode than iron
   • Lighter materials e.g. Aluminium:
     • Improve fuel economy
     • Less corrosion, will last
   • Recycling
     • Advantages: Less mining, less crude oil in plastics, less landfill
     • Disadvantages: Fewer mining jobs, difficult to separate, can pollute, expensive
     • Minimum Recyclable % laws in place

5. Manufacturing Chemicals

   • The Haber Process
     • Cover in Detail
     • Optimum Conditions
       • Iron Catalyst incr. rate of reaction (NOT percentage yield)
       • High pressure incr. Ammonia yield
       • High temperature incr. rate of reaction
       • High temp. REDUCES Ammonia yield
         • Optimum temp. 450'C
           • Quick, low yield
   • Costs of Manufacture
     • High pressure = High plant costs
     • High temp = High energy costs
     • Catalysts increase reaction
     • Automation reduces wage costs (workers)
     • Aim for cheapest yield, not fastest/ largest

6. Acids + Bases

   • Bases
     • Metal oxides/hydroxides
     • Those soluble in water called ALKALIS
       • Sodium hydroxide, calc. hydroxide
     • Alkalis contain OH- ions
   • Neutralisation
     • Acid + Base --> Salt + Water
       • H+ (Acid) + OH- (Alkali) <---> H2O
   • Universal indicator is a mix of diff. indicators
     • Shows gradual changes
   • Acids
     • All contain H+ ions
     • Higher the H+ concentration, lower the pH
   • Salts
     • Acid + Metal carbonate --> Salt + Water + CO2
     • Two-part names:
       • Sulfate, nitrate, chloride, phosphate
     • E.g: Hydrochloric acid + copper carbonate --> Copper chloride + water + carbon dioxide

7. Fertilisers + Crop Yields

   • Crops
     • Fertilisers must be dissolved in water for plant roots to absorb
     • Some dissolve easily, others designed for slow energy release
     • Yield increased by:
       • Provide extra essential elements
         • (Fertiliser)
       • Provide nitrogen encorporated into plant protein
         • Increased growth
   • Eutrophication
     • Excess fertiliser runoff causes algal bloom in river systems
       • Sunlight blocked out
         • Plants stop respiring
           • Aerobic bacteria use all oxygen
             • Fish die
     • Caused by nitrate / phosphate levels
   • Preparing Fertilisers
     • Most fertilisers are salts
       • (Water is heavy to transport)
     • Step 1: Titrate alkali and acid using indicator to find neutral
       • Step 2: Use these ratios to scale up alkali + acid
         • Step 3: Boil off most water, leave to crystalise

8. Chemicals from the Sea

   • Mining / Subsidence
     • Rock salt mined from ground
     • Pump water underground, collect salt solution
     • Can cause subsidence - destroys land + homes
     • Leaking brine solution affects habitats
   • Electrolysis of Sodium Hydroxide solution
     • Brine can be separated using electrolysis.
     • Important the electrodes are INERT
       • (Chlorine and Hyrdogen are highly reactive)
     • Equations:
       • Ions not discharged make Sodium Hydroxide solution
         • Na+ + OH- --> NaOH
       • Chlorine OXIDISED at anode
         • 2Cl- - 2e- --> Cl2
       • Hydrogen REDUCED at cathode
         • 2H+ + 2e- --> H2
   • Chlor-Alkali industry
     • Chlorine and Sodium Hydroxide important raw materials
       • Bleach
       • Paints
       • Solvents
       • Plastics
       • Foods

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