AQA A Level Chemistry Paper 2 (2025):
Organic and Physical Chemistry
Questions, Answers & Verified Marking
Scheme
Relative atomic mass (Ar) - answerAverage mass of an atom compared with one twelth
of the mass of an atom of carbon 12
Electronegativity - answerPower of an atom to attract the pair of electrons in a covalent
bond
Standard enthalpy of combustion - answerEnthalpy change when 1 mole of a substance
burns completely in oxygen under standard conditions with all reactants and products
being in their standard state
Standard enthalpy of formation - answerEnthalpy change when 1 mole of a compound
is formed from it's elements under standard conditions in their standard states
Mean bond enthalpy - answerThe average energy needed to break a certain type of
bond over a range of compounds
Activation energy - answerMinimum energy required for colliding molecules to react
Maxwell-Boltzmann distribution x and y axes - answerx: Energy
y: fraction/number of molecules
What happens to the Maxwell-Boltzmann curve when temperature increases -
answerMoves down and to the right
Rate of reaction - answerRate at which product formed/reactant used up
Order of reaction - answerPower to which the concentration of a species is raised in the
rate equation
rearrange k=Ae^-Ea/Rt - answerlnk=-Ea/Rt+lnA
Conditions for thermal cracking - answerHigh temperature and high pressure
Products of thermal cracking - answerHigh % of alkenes
,Conditions for catalytic cracking - answerHigh temperature ,slight pressure and in the
presence of a zeolite catalyst
Products of catalytic cracking - answerMotor fuels and aromatic hydrocarbons
Why do we crack alkanes? - answerSmaller alkanes/alkenes generally more useful than
longer chain ones
Equation for complete combustion of alkanes - answeralkane + oxygen > carbon
dioxide + water
Equations for incomplete combustion of alkanes - answeralkane + oxygen > carbon
monoxide/carbon + water
Pollutants produced by combustion engines - answerNOx, CO, C and sunburned
hydrocarbons
Reaction of methane with chlorine - answerI: Cl2 > 2Cl•
P: CH4 + Cl• > CH3• + Chi
CH3• + Cl2 > CH3Cl + Cl•
T: CH3• + Cl• > CH3Cl
2 equations showing decomposition of the ozone - answerCl• + O3 > ClO• + O2
ClO• + O3 > 2O2 + Cl•
What types of mechanism do haloalkanes undergo? - answer-Nucleophilic substitution
by aqueous hydroxide ions, cyanide ions or ammonia
-Elimination with ethanolic hydroxide ions
What type of mechanism do alkenes undergo? - answerElectrophilic addition by
bromine, hydrogen bromide or sulphuric acid
Test for primary or secondary alcohols - answerWarm with acidified potassium
dichromate (VI) and positive result is Solution turning green
Tests for aldehyde or ketone - answer-Warm with Fehlings Solution - brick red
precipitate indicates aldehyde
-Warm with Tollens reagent (silver nitrate + sodium hydroxide + dilute ammonia) -
aldehyde gives a silver mirror
Test for alkenes - answerShake with bromine water- alkene goes from Orange to
colourless
Test for carboxylic acids - answerSodium carbonate and effervescence is positive
Relative stabilities of carbocations - answertertiary>secondary>primary
,What are addition polymers formed from? - answerAlkenes and substituted alkenes
Conditions for dehydration of alcohols to give alkenes and water - answerHeat with
concentrated sulfuric acid
Conditions for production of ethanol by fermentation - answerYeast, anaerobic, 30-40°C
Why are racemic mixtures optically inactive?+ - answerThere are equal concentrations
of the (+) and (-) isomers
What are aldehydes oxidised to? - answerCarboxylic acids
What are aldehydes reduced to primary alcohols by and ketones reduced to secondary
alcohols by? - answerNaBH4 in aqueous solution
Conditions for production of hydroxynitriles from caronyl compounds - answerKCN
followed by dilute acid
Equations for formation of an ester (acid catalyst) - answercarboxylic acid + alcohol >
ester + water
acyl chloride + alcohol > ester + HCl
Uses of esters - answerSolvents, plasticisers, perfumes and flavourings
Products of hydrolysis of vegetable oils/animal fats in alkaline conditions - answersalts
of long chain carboxylic acids (soap) and glycerol
How is biodiesel produced? - answerReacting vegetable oils with methanol with a
catalyst
What type of mechanisms do acyl chlorides and acid anhydrides undergo with water,
alcohols, ammonia and primary amines? - answerNucleophilic addition-elimination
Reasons for making aspirin with ethanoic anhydride rather than ethanoyl chloride -
answer-Cheaper
-Safer (less corrosive)
-Doesn't produce dangerous fumes of hydrogen chloride
Equation for generation of nitronium ion - answerHNO3 + 2H2SO4 > NO2+ + 2HSO4- +
H3O+
Formation of electrophile in acylation - answerAlCl3 + ROCl > RO+ + AlCl4-
How can you prepare primary aliphatic amines? - answer-haloalkanes + ammonia
-reduction of nitriles
, Relative base Strength of amines - answer2°>3°>1°>ammonia>aromatic amines
Condensation polymers formed by reactions between: - answer-dicarboxylic acids +
diols
-dicarboxylic acids + diamines
-amines
Why can polyesters and polyamides be hydrolysed - answerC=O susceptible to
Nucleophilic attack
What charge does an amino acid form in acidic solution? - answerPositive
What charge does an amino acid form in alkaline solution? - answerNegative
What is a stereospecific active site? - answerAn active site that only one enantiomer
can fit
Developing agents for a chromatogram - answerNinhydrin or ultraviolet light
Method for Thin Layer Chromatography - answer1) Wearing gloves, draw pencil line 1
cm above bottom of plate
2) Add tiny drop of each solution using capillary tube and dry
3) Add solvent to chamber below pencil line
4) When solvent almost reaches top of plate take it out
5) Dry in fine cupboard then spray with ninhydrin and put in oven
6) Calculate Rf
Ho2 to calculate Rf - answer(Distance moved by amino acid) ÷ (Distance moved by
solvent)
How does cisplatin prevent DNA replication? - answerLigand substitution forms bond
between Platinum and nitrogens from two guanines
Test for chloroalkane - answerWarm with silver nitrate gives white ppt of AgCl
Test for acyl chloride - answerWarm with silver nitrate gives steamy fumes of Hack and
white ppt of AgCl
What will NaBH4 reduce? - answerC=O
What does hydrogen with a nickel catalyst reduce? - answerC=C
What does Sn/HCl reduce? - answerRNO2 to RNH2
What is a dehydrating agent for alcohols to alkenes? - answerheated aluminium oxide
Organic and Physical Chemistry
Questions, Answers & Verified Marking
Scheme
Relative atomic mass (Ar) - answerAverage mass of an atom compared with one twelth
of the mass of an atom of carbon 12
Electronegativity - answerPower of an atom to attract the pair of electrons in a covalent
bond
Standard enthalpy of combustion - answerEnthalpy change when 1 mole of a substance
burns completely in oxygen under standard conditions with all reactants and products
being in their standard state
Standard enthalpy of formation - answerEnthalpy change when 1 mole of a compound
is formed from it's elements under standard conditions in their standard states
Mean bond enthalpy - answerThe average energy needed to break a certain type of
bond over a range of compounds
Activation energy - answerMinimum energy required for colliding molecules to react
Maxwell-Boltzmann distribution x and y axes - answerx: Energy
y: fraction/number of molecules
What happens to the Maxwell-Boltzmann curve when temperature increases -
answerMoves down and to the right
Rate of reaction - answerRate at which product formed/reactant used up
Order of reaction - answerPower to which the concentration of a species is raised in the
rate equation
rearrange k=Ae^-Ea/Rt - answerlnk=-Ea/Rt+lnA
Conditions for thermal cracking - answerHigh temperature and high pressure
Products of thermal cracking - answerHigh % of alkenes
,Conditions for catalytic cracking - answerHigh temperature ,slight pressure and in the
presence of a zeolite catalyst
Products of catalytic cracking - answerMotor fuels and aromatic hydrocarbons
Why do we crack alkanes? - answerSmaller alkanes/alkenes generally more useful than
longer chain ones
Equation for complete combustion of alkanes - answeralkane + oxygen > carbon
dioxide + water
Equations for incomplete combustion of alkanes - answeralkane + oxygen > carbon
monoxide/carbon + water
Pollutants produced by combustion engines - answerNOx, CO, C and sunburned
hydrocarbons
Reaction of methane with chlorine - answerI: Cl2 > 2Cl•
P: CH4 + Cl• > CH3• + Chi
CH3• + Cl2 > CH3Cl + Cl•
T: CH3• + Cl• > CH3Cl
2 equations showing decomposition of the ozone - answerCl• + O3 > ClO• + O2
ClO• + O3 > 2O2 + Cl•
What types of mechanism do haloalkanes undergo? - answer-Nucleophilic substitution
by aqueous hydroxide ions, cyanide ions or ammonia
-Elimination with ethanolic hydroxide ions
What type of mechanism do alkenes undergo? - answerElectrophilic addition by
bromine, hydrogen bromide or sulphuric acid
Test for primary or secondary alcohols - answerWarm with acidified potassium
dichromate (VI) and positive result is Solution turning green
Tests for aldehyde or ketone - answer-Warm with Fehlings Solution - brick red
precipitate indicates aldehyde
-Warm with Tollens reagent (silver nitrate + sodium hydroxide + dilute ammonia) -
aldehyde gives a silver mirror
Test for alkenes - answerShake with bromine water- alkene goes from Orange to
colourless
Test for carboxylic acids - answerSodium carbonate and effervescence is positive
Relative stabilities of carbocations - answertertiary>secondary>primary
,What are addition polymers formed from? - answerAlkenes and substituted alkenes
Conditions for dehydration of alcohols to give alkenes and water - answerHeat with
concentrated sulfuric acid
Conditions for production of ethanol by fermentation - answerYeast, anaerobic, 30-40°C
Why are racemic mixtures optically inactive?+ - answerThere are equal concentrations
of the (+) and (-) isomers
What are aldehydes oxidised to? - answerCarboxylic acids
What are aldehydes reduced to primary alcohols by and ketones reduced to secondary
alcohols by? - answerNaBH4 in aqueous solution
Conditions for production of hydroxynitriles from caronyl compounds - answerKCN
followed by dilute acid
Equations for formation of an ester (acid catalyst) - answercarboxylic acid + alcohol >
ester + water
acyl chloride + alcohol > ester + HCl
Uses of esters - answerSolvents, plasticisers, perfumes and flavourings
Products of hydrolysis of vegetable oils/animal fats in alkaline conditions - answersalts
of long chain carboxylic acids (soap) and glycerol
How is biodiesel produced? - answerReacting vegetable oils with methanol with a
catalyst
What type of mechanisms do acyl chlorides and acid anhydrides undergo with water,
alcohols, ammonia and primary amines? - answerNucleophilic addition-elimination
Reasons for making aspirin with ethanoic anhydride rather than ethanoyl chloride -
answer-Cheaper
-Safer (less corrosive)
-Doesn't produce dangerous fumes of hydrogen chloride
Equation for generation of nitronium ion - answerHNO3 + 2H2SO4 > NO2+ + 2HSO4- +
H3O+
Formation of electrophile in acylation - answerAlCl3 + ROCl > RO+ + AlCl4-
How can you prepare primary aliphatic amines? - answer-haloalkanes + ammonia
-reduction of nitriles
, Relative base Strength of amines - answer2°>3°>1°>ammonia>aromatic amines
Condensation polymers formed by reactions between: - answer-dicarboxylic acids +
diols
-dicarboxylic acids + diamines
-amines
Why can polyesters and polyamides be hydrolysed - answerC=O susceptible to
Nucleophilic attack
What charge does an amino acid form in acidic solution? - answerPositive
What charge does an amino acid form in alkaline solution? - answerNegative
What is a stereospecific active site? - answerAn active site that only one enantiomer
can fit
Developing agents for a chromatogram - answerNinhydrin or ultraviolet light
Method for Thin Layer Chromatography - answer1) Wearing gloves, draw pencil line 1
cm above bottom of plate
2) Add tiny drop of each solution using capillary tube and dry
3) Add solvent to chamber below pencil line
4) When solvent almost reaches top of plate take it out
5) Dry in fine cupboard then spray with ninhydrin and put in oven
6) Calculate Rf
Ho2 to calculate Rf - answer(Distance moved by amino acid) ÷ (Distance moved by
solvent)
How does cisplatin prevent DNA replication? - answerLigand substitution forms bond
between Platinum and nitrogens from two guanines
Test for chloroalkane - answerWarm with silver nitrate gives white ppt of AgCl
Test for acyl chloride - answerWarm with silver nitrate gives steamy fumes of Hack and
white ppt of AgCl
What will NaBH4 reduce? - answerC=O
What does hydrogen with a nickel catalyst reduce? - answerC=C
What does Sn/HCl reduce? - answerRNO2 to RNH2
What is a dehydrating agent for alcohols to alkenes? - answerheated aluminium oxide
