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Industrial Chemistry (Focus 3 (3.2 (Issus w/ extract. (Easily oxidised to…

- - - - Superphosphate fertil. (calcium sulfates (insol.) & calcium dihydrogen phosphates)
      - Ammonium sulphate - H2SO4(aq) + 2NH3(aq) --> (NH4)2SO4(aq)
    - - Remove surface rust (iron oxide) & grease/dirt from steel before galvanising/coating
    - - Conc. H2SO4 used in prod. ethylene from ethanol
        
        Water removed - C2H5OH(l) -H2SO4-> C2H4(g) + H2O(l)
      - Also for drying gas for explosives, dyes
  - - - Superheated water (160°C) outer, melts sulphur
      - Liquid sulphur & water middle, S separates when solid
      - Compress. air inner, pushes emulsion up
    - - Incomp. combust. of H2S
      - 4H2S(g) + O2(g) --> 2H2S(g) + S(s) +SO2(g) + 2H2(g)
      - 2H2S(g) + SO2(g) --> 2H2O(g) +3S(g) - mix. is condensed
    - - Low MP (113°C - water melts sulphur)
      - Low density (foamy mix. w/ water easily lifted up)
      - Insol. in water so extract. only req. cooling (99.5% S)
    - - Easily oxidised to SO2 or red. to H2S - air poll. @ low conc. (acid rain)
      - Water may diss. impur. & maybe contam. - water should be reused
      - Water may cause thermal poll. to environ.
      - Earth subsidences (diff. to refill cavern, may collapse)
  - - - S(s) + O2(g) --> SO2(g)
      - Molten sulphur sprayed into furnace w/ air that has been dried (w/ excess oxygen) in combust. furnace
      - Sulphur dioxide also from metal refineries, e.g. 2ZnS(s) + 3O2(g) --> 2ZnO(s) + 2SO2(g)
    - - 2SO2(g) + O2(g) ⇌ 2SO3(g) ∆H = -99kJ/mol
      - Sulphur dioxide fed into a conversion tower, convert. it into sulphur trioxide through catalytic oxidation
      - Press. 1 atm, excess of oxygen, 400-550°C, catalyst vanadium pentaoxide V2O5 on porous silica pellets
      - Goes through @ 550°C, then twice @ 400°C to ensure max. SO2 convert. - 99.7%
    - - SO3(g) + H2O(l) --> H2SO4(l)
      - Reaction is v. exo. & H2SO4 becomes a mist - too expen. to sep. from gas
      - Sulfur trioxide ∴ diss. into conc. sulphuric acid to form oleum H2S2O7 - SO3(g) + H2SO4(l) --> H2S2O7(l) then H2S2O7(l) + H2O(l) --> 2H2SO4(l)
      - Produces 98% H2SO4
  - - - S(s) + O2(g) --> SO2(g) + heat
        
        Oxidation of sulphur done in a combust. furnace & goes to comple.
        
        MOlten sulphur sprayed into dry, oxygen-rich air
    - - 2SO2(g) + O2(g) ) ⇌ 2SO3 (g) + heat (∆H = −99kJ/mol)
      - Oxidation of sulphur dioxide is reversible & reaches equil.
      - Reaction in conversion tower w/ vanadium pentaoxide V2O5 on porous silica pellets as catalyst
      - SO2 & O2 cooled to 550°C, & passed through catalyst - 70% conversion (high. rate)
      - SO2 & O2 cooled to 400°C, & passed through catalyst - 97% conversion (high. yield)
      - SO3 is removed, remain. SO2 & O2 cooled to 400°C & passed through catalyst - 99.7%
      - Residue gas release. into atm.
  - - - Sulphur should be liquid & sprayed to increase SA to inc. reaction rate
      - No equil. consid. req.
    - - 2SO2(g) + O2(g) ⇌ 2SO3 (g) + heat (∆H = −99kJ/mol)
      - Reaction rate inc. by
        
        High temp. - more molecular collisions
        
        Catalyst - Vanadium oxide lowers activation energy
      - Yield inc. accord. to Le Chatelier's Principle
        
        Low. temp. - favours products
        
        High. press. - as there are less moles of gas produced
        
        Excess of oxygen - shifts equil. to right
      - Compromise
        
        400°C - 500°C, press. @ 1 atm reduces costs
  - - - Oxidising agent (oxidant) becomes reduced - it brings about oxidation
        
        H2SO4 ∴ gains electrons (OILRIG)
      - W/ copper
        
        Cu(s) + 2H2SO4(aq) --> CuSO4(aq) + SO2(g) + 2H2O(l)
      - W/ iodide ions
        
        2I-(aq) + 3H2SO4(aq) --> I2(aq) + SO2(aq) + 2H2o(l) + 2HSO4-(aq)
    - - Sulphuric acid has strong affinity - & absorbs water from mixtures
      - SUlphuric acid dehydrates sucrose to create carbon (spongy) & water
        
        C12H22O11(s) -H2SO4-> 12C(s) + 11H2O(l)
      - Used for esterification & remove. water from alkanols
  - - - H+ combin. w/ water form H3O+ ions
      - This energy releases much greater energy than breaking bonds of H2SO4
      - ∴ ionisation is strongly exo.
    - - Only occurs slightly, negligible (K = 1.2 x 10-2)
  - - - Allows heat to disperse & prevents water from boiling
- - - - Triglycerides - compound w/ 3 esters bonded to one glycerol (forms 3 H2O)
    - - E.g. Lauric Acid (12-C) w/ carboxylic tail
    - - NaOH or KOH used as bases
  - - - Raw materials - Pure oils (e.g. olive oil) NaOH solution
      - Mix., stirring - mixed & stirred w/ glass rod
      - Time, °C, atm - 45min - 1hour; standard 25°C; 1atm
      - Contain. - beaker
      - Catalyst - none
      - Safety, disposal - heat gently, NaOH; sink w/ water
      - Further process. - washing to remove NaOH
    - - Raw materials - Mix. of fats & oils, e.g. waste fats
      - Mix., stirring - kettle method w/ high press. steam
      - Time, °C, atm - many days; 250°C; 5atm
      - Contain. - steel contain., 100t. capacity (kettle)
      - Catalyst - metal catalyst
      - Safety, disposal - high press.; glycerol recovered, unreacted fatty acids reused
      - Further process. - washed w/ steam, distilled to remove impur., colours & perfumes added
  - - - Interfacial tension - force between two immiscible liquids
    - - Soap's hydrophobic tail attaches to grease, head remains in water
      - Grease is lifted off object, soap surrounds grease
      - Further agitation of mix. lifts off other grease/dirt on object
      - Grease & soap are negatively charged & repel each other to prevent joining together
  - - - Are a class of surfactants, ∴ reduces interfacial tension
    - - More water the oil, so oil is dispersed in water
  - - - Soaps (natural)
        
        Soaps contain a long non-polar hydrocarbon chain & a polar anionic carboxylate end.
        
        DOesn't function well in hard water as it reacts w/ Mg2+ & Ca2+ ions to form insoluble salts
      - Anionic detergents (synthetic)
        
        Anionic detergents contain a non-polar hydrocarbon chain & a polar benzene sulphonate
        end.
        
        Hard water does have a slight effect on effectiveness
      - Cationic detergents (synthetic)
        
        Cationic detergents contain a non-polar hydrocarbon chain & have ammonium as their polar end
        
        Hard water doesn't react w/ cations & are v. effective in hard water
      - Non-ionic detergents (synthetic)
        
        Non-ionic detergents
        have contain a non-polar hydrocarbon chain have the hydroxyl group
        
        Hard water doesn't react w/ ions & are v. effective. in hard water
  - - - Removing non-oily surfactants
    - - Hair conditioners & fabric softeners
    - - Dishwashing liquids & laundry detergents
    - - Front-loading washing machines & dishwashers
    - - Soaps
        
        Soaps are biodegradable
      - Detergents
        
        Detergents used to be branched but this contributed to poor biodegradability. This led to excessive frothing in rivers. Today, detergents are straight hydrocarbon chains which make them biodegradable. But, detergents often contain builders which enhance their cleaning ability by
        softening the water. The problem with builders is their contribution to eutrophication which is
        detrimental to aquatic ecosystems.
- - - - Change in press. (inc.)
        
        A is gas, then equil. shift to the right
        
        Speeds up rate of reaction as molecules are closer together
      - Change in vol. (inc.)
        
        C is a gas, then equil. shift left
        
        Speeds up rate of reaction as molecules are closer together
      - Change in conc. (inc.)
        
        A is inc., equil. shift right
      - Change in temp. (inc.)
        
        Reaction is exo., equil. shift left
        
        Speeds up rate of reaction as molecules move faster, & more chances to react
  - - - Where [] is equil. conc., only when in equil, otherwise Q, a reaction variable
  - - - Exo.
        
        Inc. temp (more reactants) - high. denominator (K dec.)
        
        Dec. temp (more products) - high. numerator (K inc.)
      - Endo.
        
        Inc. temp (more products) - high. numerator (K inc.)
        
        Dec. temp. (more reactants) - high. denominator (K dec.)
- - - - Only the sign of the elctrodes are swapped
  - - - Ca removed by NaCO3, Mg removed by NaOH, Fe removed by NaCO3/NaOH, SO4 removed by CaCl2
      - Precip. removed as a sludge
  - - - Process & struct.
        
        Two tanks connect. w/ mercury (cathode_, where Na+ reduced (gains electrons)
        
        Purified brine pumped into 1st tank - Cl- oxidised on titanium plates (anode) (loses electrons)
        
        Cl2 gas bubbles collect., Na forms amalgram w/ mercury (Na/Hg)
        
        2nd tank contain. purified water - reacts w/ sodium
        
        H2 gas bubbles collect., NaOH removed, mercury poumped back to 1st tank
      - Chem.
        
        @ the anode - Na+(aq) + e- --> Na/Hg
        
        @ the cathode - 2Cl-(aq) --> Cl2(g) + 2e- (titanium anode)
        
        In the 2nd tank - 2Na(s) + 2H2O(l) --> 2NaOH(aq) + H2(g)
        
        Overall - 2NaCl(aq) + 2H2O --> 2NaOH(aq) + H2(g) + Cl2(g)
      - Tech. diff.
        
        Anode is made from inert titanium plates as Cl2 is corrosive & strong oxidant
        
        Mercury used as it forms amalgrams w/ metals, liquid - easily pumped around
        
        Large amounts of currents used to allow electrolysis - 3-4 V
        
        Produces v. pure NaOH & avoids using asbestos
      - Enviro. diff.
        
        Mercury may be lost & discharged into enviro. - heavy metal & neurotoxin
    - - Process & struct.
        
        Asbestos diaphragm separates anode & cathode comaprtments
        
        Carbon (anode), steel mesh (cathode)
        
        Water reduces in cathode to OH- ions
        
        Na+ ions attract. to cathode, migrate across asbestos diaphragm
        
        Cl2 gas, H2 gas removed & NaOH & NaCl solution purified by crystallising NaCl
      - Chem.
        
        @ the anode - 2Cl-(aq) --> Cl2(g) + 2e-
        
        @ the cathode - 2H2O(l) + 2e- --> 2OH-(aq) + H2(g)
        
        Overall - 2NaCl(aq) + 2H2O(l) --> 2NaOH(aq) + Cl2(g) + H2(g)
      - Tech. diff
        
        Chlrine gas - anode made of carbon
        
        Cl2 gas & H2 gas separated to prevent reaction to form HCl gas (corrosive)
        
        Many cells used to inc. current - 3.5 - 5V
        
        Asbestos doesn't always stop Cl- & OH- ions - NaCl & ClO- (strong oxidant) created
      - Enviro. diff.
        
        Asbestos fibres dangerous, inhalation causes lung diseases
        
        Depleted brine may contain NaOH - can't be released into enviro.
    - - Diaphragm cell, but w/ ion exchange polymer membrane made of polytetrafluoroethylene (PTFE)
        
        Membrane only allows movement of water & Na+ ions
      - Chem.
        
        @ the anode - Cl-(aq) --> Cl2(g) + 2e-
        
        @ the cathode - 2H2O(l) + 2e- --> 2OH-(aq) + H2(g)
        
        Overall - NaCl(aq) + H2O(l) --> NaOH(aq) + Cl2(g) + H2(g)
      - Tech. diff.
        
        No toxic materials used - polymer is inert
        
        Polymer has selective permeability
        
        Anode made of titanium due to resist. to Cl2, 3.5 - 5V, large amount of current
      - Enviro. diff.
        
        V. few, other than leakages of Cl2, NaOH or depleted brine
- - - - Brine (sat. NaCl solution)
      - Limestone (calcium carbonate, CaCO3)
      - Ammonia (NH3)
    - - Sodium Carbonate (Na2CO3)
      - Calcium Chloride (CaCl2)
  - - - Cheap alkali, able to neutralize acid in factories, labs.
      - Alter. base in saponification
  - - - Brine sat. w/ ammonia
      - CO2 bubbled through to produce NaHCO3
      - NaHCO3 filtered & heated to form Na2CO3
      - Ammonia regen. from filtrate
      - 2NaCl(aq) + CaCO3(s) --> Na2CO3(s) + CaCl2(aq)
    - - Brine conc. inc. to 30%
      - Brine from sea water is purif. to remove
        Mg2+ & Ca2+
        ions – NaCO3 & NaOH added
        to precip. ions out
      - Flocculant added & precip. skimmed off
      - Limestone is relative. pure
- - - - Clovers grown as its roots have nitrgoen-fixing bacteris
      - Saltpetre (sodium nitrate) depos. in northern Chile
      - Guano from sun-baked bird droppings (nitrates & phosphates), e.g. Peruvian coast & from bats
        
        From 1840s guano traded worldwide
        
        1850s Britain controlled trade, 1856 50 guano islands became US property
        
        1970s depletion of organic guano
        
        After 1970s, mining of saltpetre
    - - Haber process nitrogen & hydrogen produced ammonia
      - Oswald process ammonia produced nitric acid
      - Nitric acid reacts w/ ammonia to form ammonium nitrate, replace. for organic fertilisers
        
        NH3(aq) + HNO3(aq) --> NH4NO3(aq)
      - Allowed Germany to stop relying on imports from Chile - esp. WW1