PAPER 2 EXAM Qs

Subdecks (4)

Cards (96)

  • When an excess of water is added to ethanal a similar nucleophilic addition reaction occurs. CH3CHO(aq) + H2O(l) ⇌ CH3CH(OH)2(aq)
    Suggest why this reaction is slower than the reaction in Question 09.5. (with chloroethanal)
    • M1 C in C=O is less δ+ / less electron deficient
    • M2 Because CH3 attached is electron donating Or CH3 has a (positive) inductive effect
    • M3 So higher activation energy
  • Explain, in terms of structure and bonding, why is BENZENE RING more thermodynamically stable than Kekule's model
    • Pi electrons are delocalised
  • Suggest why chemists usually aim to design production methods
    • with fewer steps
    • with a high percentage atom economy.
    1. Less energy used OR Better yield
    • reduces practical losses, simpler plant,
    • 2) Less waste OR Less pollution
    • OR maximises the use of raw materials in the process into useful products, saves resources
  • 0 9 . 1 State why the ozone layer is beneficial for living organisms.
    • Absorbs / prevents harmful UV
  • Suggest an extra step to ensure that the mass of olive oil in the solution is recorded accurately. (In titration) [2 marks, 2022]
    • Extra step: Weigh the bottle after oil transfer (and record the mass)
    • Justification: Not all of the oil is transferred Or so that the mass of oil left in the bottle is accounted for Or find the exact mass of oil used
  • 0 9 . 4 State the reason for inverting the flask several times.
    • 09.4 To ensure the solution is homogeneous
    • Allow evenly mixed/ distributed / uniform solution
  • Disadvantages of Route A (2 step synthesis, KCN)
    • Lower yield (because of two steps)
    Disadvantages of Route B (Nucleophilic subs with amine)
    • FURTHER SUBSTITUTION IS LIKELY
  • Suggest how you could show the atenolol produced by reduction of a ketone was a racemate and NOT a single enantiomer
    • shine plane polarized light
    • If racemate, no effect on plane polarized light as enantiomers rotate light opposite directions equally
  • State the property of Sulfur dioxide (gas) that causes pollution when it enters rivers
    • acid(ic) / acidity / produces H +
    • OR lowers pH
  • Draw a diagram to show the shape of a molecule of H2O Include any lone pairs of electrons.
    State the H−O−H bond angle.
    Explain this shape and bond angle.
    • 104.5 degrees
    • lone pairs repel more strongly than bonding pairs
    • so bond angle reduced from/less than 109½° / tetrahedral
    • ALLOW reduced by 2.5° per lone pair or 5°
  • Suggest one reason why chlorobenzene (C6H5Cl) does not react with ammonia under normal conditions.
    • electron rich ring or benzene or pi cloud REPELS! nucleophile/ammonia
  • Organic Synthesis Exam Question
    Give one disadvantage of Route A - sub with KCN, then reduction Ni + H2
    • Route A - lower YIELD because two steps
    • OR KCN is poisonous (3.8 spec) // Expensive LiAlH4
    Route B - Nucleophilic substitution with excess ammonia
    - Further reaction/substitution likely // impure product
  • Give one advantage and one disadvantage of manufacturing ethanol by fermentation rather than by hydration. Do not include energy consumption or cost.
    ADVANTAGES
    • low technology
    • renewable feedstock / resource
    • allowed for use in drinks, perfumes
    • considered to be green
  • Give one advantage and one disadvantage of manufacturing ethanol by fermentation rather than by hydration. Do not include energy consumption or cost.
    DISADVANTAGES
    • slow
    • low yield
    • significant land use (for growing sugar canes)
    • has to be distilled
    • (labour intensive?)
  • State one advantage and one disadvantage of the production of ethanol by the hydration of ethene compared to the fermentation of glucose.
    ADVANTAGE
    • Fast reaction OR pure product
    • OR continuous process
    • OR cheap on manpower
    • OR high yield, 100% alcohol
  • State one advantage and one disadvantage of the production of ethanol by the hydration of ethene compared to the fermentation of glucose.
    Disadvantage
    • High technology
    • OR ethene from non renewable source
    • OR expensive equipment not just costly
  • In the manufacture of margarine, unsaturated vegetable oils such as sunflower oil are hardened.
    (i) State the reagent and conditions used in this process
    • Reagent = Hydrogen
    • Conditions - Nickel catalyst
    • Heat (100-200 degrees)
  • Nonane is often found in fuel for jet engines. Combustion in jet engines produces pollutants including nitrogen monoxide (NO). Explain how this nitrogen monoxide is formed. [2 marks]
    • M1 nitrogen and oxygen from air react
    • M2 at high temperature (if temperature stated, over 1000C)
  • Use your understanding of properties of PVC to explain whether you'd expect a plasticiser in PVC used to insulate electrical cables [2 marks] = Need both ideas that
    • it is present
    • AND because PVC needs to be flexible / bendy
  • The characteristics of a homologous series, a series of compounds containing the same functional group
    • Any two from
    • chemically similar or chemically the same or react in the same way
    • same functional group
    • same general formula
    • differ from CH2
  • Explain what is meant by the term fuel
    • release (heat) ENERGY! (when burned) (1)
    • OR provides a (useable form of) energy
    • OR is a source of energy
  • Crude oil is separated into fractions by fractional distillation. Outline how different fractions are obtained by this process. [3 marks]
    • Crude oil is heated to vaporise it / oil VAPOURISED (1)
    • (Vapour passed into fractionating) tower / COLUMN (1)
    • Top of tower cooler than bottom or negative temperature gradient (1) OR condenses at different temperatures
    • fractions separated by boiling point
  • Use the data given above to explain why catalytic cracking of crude oil fractions is commercially important.
    • Identify shortfall in supply - e.g. petrol / small molecules (1)
    • Higher value products OR more useful products (1)