AQA A-level Chemistry Paper 1
Exam Question and Answers
May 2024
Explain what is meant by the term co-ordinate bond -
Answer>> a covalent bond in which both electrons are
donated by one atom
Define the term Ligand - Answer>> Atom, ion or
molecule which can donate a pair of electrons to a metal
ion
What can lattice enthalpy defined as? (2 things) -
Answer>> Lattice enthalpy of formation and lattice
enthalpy of dissociation
Why is the experimental value for lattice dissociation of
some compounds greater than the theoretical value? -
Answer>> the bonding is not 100% ionic/ there is some
covalent character/ there is additional covalent bonding
what does the perfect ionic model assume? - Answer>>
The bonding in the compound is not 100% ionic. In the
model the ions are perfect spheres/point charges are not
distorted
, What 2 things might cause a different lattice enthalpy? -
Answer>> Enthalpy of bond dissociation (eg halogens)
Enthalpy of formation
why is the lattice enthalpy greater for ions with a high
charge? - Answer>> There is a stronger attraction
Why is the lattice enthalpy greater for smaller ions? -
Answer>> smaller ions are more closely packed in the
lattice
there is a stronger attraction
what is the relationship between enthalpy of lattice
dissociation and enthalpy of lattice formation? -
Answer>> same numerical value but different signs
State Hess' law - Answer>> Enthalpy change for any
chemical reaction is independent of the route taken, and
depends only on the initial and final states.
Why is the second electron affinity endothermic? -
Answer>> Repulsion of the negative ion with the
negative electron being added
Define enthalpy of hydration - Answer>> The enthalpy
change when 1 mole of gaseous ions is converted to one
mole of aqueous ions
Exam Question and Answers
May 2024
Explain what is meant by the term co-ordinate bond -
Answer>> a covalent bond in which both electrons are
donated by one atom
Define the term Ligand - Answer>> Atom, ion or
molecule which can donate a pair of electrons to a metal
ion
What can lattice enthalpy defined as? (2 things) -
Answer>> Lattice enthalpy of formation and lattice
enthalpy of dissociation
Why is the experimental value for lattice dissociation of
some compounds greater than the theoretical value? -
Answer>> the bonding is not 100% ionic/ there is some
covalent character/ there is additional covalent bonding
what does the perfect ionic model assume? - Answer>>
The bonding in the compound is not 100% ionic. In the
model the ions are perfect spheres/point charges are not
distorted
, What 2 things might cause a different lattice enthalpy? -
Answer>> Enthalpy of bond dissociation (eg halogens)
Enthalpy of formation
why is the lattice enthalpy greater for ions with a high
charge? - Answer>> There is a stronger attraction
Why is the lattice enthalpy greater for smaller ions? -
Answer>> smaller ions are more closely packed in the
lattice
there is a stronger attraction
what is the relationship between enthalpy of lattice
dissociation and enthalpy of lattice formation? -
Answer>> same numerical value but different signs
State Hess' law - Answer>> Enthalpy change for any
chemical reaction is independent of the route taken, and
depends only on the initial and final states.
Why is the second electron affinity endothermic? -
Answer>> Repulsion of the negative ion with the
negative electron being added
Define enthalpy of hydration - Answer>> The enthalpy
change when 1 mole of gaseous ions is converted to one
mole of aqueous ions
