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ORGANIC CHEMISTRY EXAM | APPROVED QUESTIONS AND
ANSWERS | GRADED A+ | LATEST 2025-2026
A large excess of both H2O2 and I- means that the rate equation is
simplified to rate=k(H+)
Explain why the use of a large XS of H2O2 and I- means that the rate
of reaction at a fixed temperature depends only on
the concentration of H+ ions (2) - Correct Answer✔✔-- there are
negligible changes on rate as h2o2 and I- concentrations are constant
- H2O2 and I- are in zero order
An additional step is required in proton NMR for the identification of
NH3 and OH- groups
Describe this additional step and explain why it is necessary [2] -
Correct Answer✔✔-- D20 is added and mixed with the sample
- deuterium replaces the hydrogen on the OH and NH so peaks for
those do not show in the second spectrum making them identifiable
Describe how you would carry out a simple test tube reaction to
confirm that the sample of propanal obtained by distillation does not
contain any propanoic acid (2) - Correct Answer✔✔-add sodium
carbonate
effervescence - propanoic acid is present
Describe how you would distinguish between separate samples of
the two enantiomers of the branched aldehyde C5H10O - Correct
Answer✔✔-- shine plane polarised light
- each enantiomer will rotate in opposite directions
Explain how the oxides of nitrogen are formed in engines - Correct
Answer✔✔-reaction of nitrogen and oxygen in the air forming NO2
1
, 2
at high temperatures
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explain what is meant by the term homologous series [2] - Correct
Answer✔✔-- compounds with the same functional group
- each successive member differs by CH2
Explain why amine U is a weaker base than amine W. (3) (U is a
aromatic amine) - Correct Answer✔✔--Lone or electron pair on N
-Delocalised or spread into ring in U
-Less available (to accept protons) or less able to donate (to H+)
explain why bond length data helped disprove the Kekule model and
was used as evidence for the delocalised model [2] - Correct
Answer✔✔-- the bond lengths in benzene are all the same
- bond length value is between the bond lengths of the kekule model
- in kekule model there would have been two values for
explain why compound K is the major product in the reaction after
electrophilic addition (3) - Correct Answer✔✔-- K is formed from a
more stable carbocation
- major product is formed from from tertiary carbocation
- stability is sue to more electron releasing alkyl groups than a
secondary carbocation
explain why it is important to open the tap of the separating funnel
periodicaally - Correct Answer✔✔-to avoid pressure build up and
release pressure
Explain why NaBH4 reduces 2-methylbutanal but has no reaction
with 2-methylbut-1-ene. - Correct Answer✔✔-H- ion is attracted to
the s+ on THE CARBOPN ATOM
C=C in 2-methylbut-1-ene is electron rich
so H- nucleophile is repelled
2
1|Page
ORGANIC CHEMISTRY EXAM | APPROVED QUESTIONS AND
ANSWERS | GRADED A+ | LATEST 2025-2026
A large excess of both H2O2 and I- means that the rate equation is
simplified to rate=k(H+)
Explain why the use of a large XS of H2O2 and I- means that the rate
of reaction at a fixed temperature depends only on
the concentration of H+ ions (2) - Correct Answer✔✔-- there are
negligible changes on rate as h2o2 and I- concentrations are constant
- H2O2 and I- are in zero order
An additional step is required in proton NMR for the identification of
NH3 and OH- groups
Describe this additional step and explain why it is necessary [2] -
Correct Answer✔✔-- D20 is added and mixed with the sample
- deuterium replaces the hydrogen on the OH and NH so peaks for
those do not show in the second spectrum making them identifiable
Describe how you would carry out a simple test tube reaction to
confirm that the sample of propanal obtained by distillation does not
contain any propanoic acid (2) - Correct Answer✔✔-add sodium
carbonate
effervescence - propanoic acid is present
Describe how you would distinguish between separate samples of
the two enantiomers of the branched aldehyde C5H10O - Correct
Answer✔✔-- shine plane polarised light
- each enantiomer will rotate in opposite directions
Explain how the oxides of nitrogen are formed in engines - Correct
Answer✔✔-reaction of nitrogen and oxygen in the air forming NO2
1
, 2
at high temperatures
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explain what is meant by the term homologous series [2] - Correct
Answer✔✔-- compounds with the same functional group
- each successive member differs by CH2
Explain why amine U is a weaker base than amine W. (3) (U is a
aromatic amine) - Correct Answer✔✔--Lone or electron pair on N
-Delocalised or spread into ring in U
-Less available (to accept protons) or less able to donate (to H+)
explain why bond length data helped disprove the Kekule model and
was used as evidence for the delocalised model [2] - Correct
Answer✔✔-- the bond lengths in benzene are all the same
- bond length value is between the bond lengths of the kekule model
- in kekule model there would have been two values for
explain why compound K is the major product in the reaction after
electrophilic addition (3) - Correct Answer✔✔-- K is formed from a
more stable carbocation
- major product is formed from from tertiary carbocation
- stability is sue to more electron releasing alkyl groups than a
secondary carbocation
explain why it is important to open the tap of the separating funnel
periodicaally - Correct Answer✔✔-to avoid pressure build up and
release pressure
Explain why NaBH4 reduces 2-methylbutanal but has no reaction
with 2-methylbut-1-ene. - Correct Answer✔✔-H- ion is attracted to
the s+ on THE CARBOPN ATOM
C=C in 2-methylbut-1-ene is electron rich
so H- nucleophile is repelled
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