C6 - Chemical Synthesis

Chemical Industry
1. Food additives
2. Cleaning products
  1. Bleach/ oven cleaner/ washing up liquid developed by chemists
3. Drugs
  1. Pharmaceutical industry is huge
4. Fertilisers
  1. Contain lots of ammonia, produced by chemical industry
5. Decorating products
  1. Paints etc contain pigments and dyes
6. Large Scale
  1. Need lots of
    1. Ammonia
    2. Sulfuric acid
    3. Sodium hydroxide
    4. Phosphoric acid
7. Small Scale
  1. Still important but less is needed
    1. Pharmaceuticals
      1. Has largest share of industry
    2. Fragrance
    3. Flavourings
8. Some sold directly to consumers, some sold to industries as raw products
Acids and Alkalis
1. 1. Pure acidic compounds
    1. Solid e.g. citric acid
    2. Liquid e.g. sulfuric acid
    3. Gas e.g. hydrogen chloride
  2. Common alkalis
    1. Sodium hydroxide e.g. bleach
    2. Potassium hydroxide e.g. alkaline batteries
    3. Calcium hydroxide e.g. neutralise acidic soils
2. Indicators/ pH meters tell us pH
  1. Litmus paper
    1. Alkali
    2. Acid
  2. Universal Indicator
    1. Combination of dyes allow pH estimation
  3. pH Meter
    1. Probe and meter
      1. Accurate pH reading
      2. More accurate than indicators
3. Acid
  1. pH< 7
  2. H+ ions in water
  3. Aqueous hydrogen ions
4. Alkali
  1. pH> 7
  2. Aqueous hydroxide ions
  3. OH - ions in water
5. Neutralisation
  1. H+(aq) + OH- (aq) ---> H2O (aq)
  2. Acid + Alkali ---> Salt + Water
  3. pH 7 - not acid or alkali (neutral)
Acids with Metals
1. Acid + Metal --> Salt + Hydrogen
  1. More reactive = faster reaction
    1. Copper doesn't react as it's less reactive than hydrogen
    2. Speed determined by rate of hydrogen bubbles given off
  2. Hydrogen is confirmed through lit splint
    1. Squeaky pop
2. Acid + Metal Carbonate--> Salt + Water + Carbon Dioxide
  1. Hydrochloric acid + sodium carbonate --> sodium chloride + water + carbon dioxide
  2. Sulfuric acid + calcium carbonate --> calcium sulfate + water + carbon dioxide
3. Acid + Metal Hydroxide --> Salt + Water
  1. Hydrochloric acid + sodium hydroxide --> sodium hydroxide + water
  2. Sulfuric acid + calcium hydroxide --> calcium sulfate + water
4. Acid + Metal Oxide --> Salt + Water
  1. Hydrochloric adid + magnesium oxide --> magnesium chloride + water
  2. Sulfuric acid + Zinc oxide --> zinc sulfate + water
5. Sulfuric Acid produces Chloride Salts
  1. Sulphuric acid + magnesium --> magnesium sulfate + hydrogen
  2. Sulfuric acid + aluminium --> aluminium sulfate + hydrogen
6. Hydrochloric Acid produces Sulphate Salts
  1. Hydrochloric acid + magnesium --> magnesium chloride + hydrogen
  2. Hydrochloric acid + aluminium --> aluminium chloride + hydrogen
7. The combination of metal and acid decides the salt
Synthesising Compounds
1. 7 stages
2. 1) Choosing the Reaction
  1. 2) Risk Assessment
    1. 3) Calculating Quantities of Reactants
      1. 4) Choosing the Apparatus and Conditions
        5) Isolating the Product
        6) Purification
        7) Measuring Yield and Purity
        Tells overall success of reaction
        Compares total possible amount with amount actually received
        Actual yield = Mass of pure product received
        Theoretical yield = maximum possible mass could get
        PERCENTAGE YIELD = ACTUAL YIELD/ THEORETICAL YIELD X 100
        Purity must be measured
        How much actual substance
        High yield and purity wanted
        Isolating helps purification
        Crystalilsation
        Finished products separate from reaction mixture
        Evaporation if product is dissolved
        Filtration if insoluble solid
        Separate solid from liquid
        Drying to remove water
        Drying oven
        Hot, dry air
        Desiccaotr
        Chemicals e.g. silica gel to remove water
        Correct size
        Hold all reactants and products
        Correct strenth
        For type of reaction e.g. hot temperatures
        Temperature of reaction
        Concentration of reactants
        If catalyst needed
      2. How much needed to produce required amount of product
      3. How much raw material is needed
      4. Reduce waste/ money loss
    2. Identifying hazards
    3. Who may be harmed
    4. What action can reduce risk
  2. Which reaction you're using
  3. Neutralisation - acid and alkali react to produce a sale
  4. Thermal decomposition - heat used to break a compound into simpler substances
  5. Precipitation - an insoluble solid is formed when 2 solutions are mixed
Mass Calculations
2. Work out masses needed/ theoretical amounts of reactions
Purity
1. Isolation improves the purity of the product
  1. Repeating filtration/ evaporation/ crystallisation will improve this
2. The purity required depends on the product
  1. High purity
    1. Petrochemicals
      1. Impurities can cause damage to engines
    2. Pharmaceuticals
      1. Drugs for human consumption must be pure so they don't harm
  2. Little purity required
    1. Fertilisers
Energy Transfer in Reactions
1. Exothermic
  1. More bonds made than broken
    1. Energy given out
      1. Increase temperature
  2. Products lower energy than reactants
  3. Controlling reactions
    1. Heat must be removed
      1. Temperature will increase
    2. Rate of reaction will also increase and reaction will get hotter
    3. Too hot = increase rate/ uncontrollable/ explosion
2. Endothermic
  1. More bonds broken than made
    1. Energy taken in
      1. Temperature decrease
  2. Products higher energy than reactants
  3. Controlling reaction
    1. Heat needs to be provided to continue reaction
    2. Slow down rate
    3. Mix could freeze, damaging equipment and stopping process
Rates of Reaction
1. How quickly reactants turned into products
  1. Slow
    1. Rusting iron
    2. Chemical weathering (acid rain)
  2. Fast
    1. Burning
    2. Explosion
  3. Moderate
    1. Metal with acid
2. Controlling the Rate
  1. Safety
    1. Too quick = explosion
      1. Dangerous
  2. Economic
    1. High rate = increase temperature
      1. Costs to maintain
      2. More product in less time
    2. Choose optimum conditions for low costs
      1. Compromise on rate of production/yield
    3. Want best yield and rate of production for lowest cost
3. Increasing rate:
  1. Larger surface area
    1. More exposed particle to react
  2. Increase concentration
    1. More particles to react
  3. Increase temperature
    1. More energy = faster moving = more frequent collision
  4. Add catalyst
    1. Surface to stick to to increase collision chance
  5. More collisions = higher reaction rate
Measuring rates of Reaction

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C6 - Chemical Synthesis

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