AQA A-level Chemistry Paper 1 EXAM
QUESTIONS (35 TERMS) WITH VERIFIED
DEFINITIONS UPDATED 2024
1). Explain what is meant by the term co-ordinate bond
Ans: a covalent bond in which both electrons are donated by one atom
2). Define the term ligand
Ans: Atom, ion or molecule which can donate a pair of electrons to a metal ion
3). What can lattice enthalpy defined as? (2 things)
Ans: Lattice enthalpy of formation and lattice enthalpy of dissociation
4). Why is the experimental value for lattice dissociation of some compounds greater than the
theoretical value?
Ans: the bonding is not 100% ionic/ there is some covalent character/ there is
additional covalent bonding
5). What does the perfect ionic model assume?
Ans: The bonding in the compound is not 100% ionic. In the model the ions are perfect
spheres/point charges are not distorted
6). What 2 things might cause a different lattice enthalpy?
Ans: Enthalpy of bond dissociation (eg halogens)
Enthalpy of formation
7). Why is the lattice enthalpy greater for ions with a high charge?
Ans: There is a stronger attraction
Why is the lattice enthalpy greater for smaller ions?
PaperStoc.com Page 1 of 5
, 8).
Ans: smaller ions are more closely packed in the lattice
there is a stronger attraction
9). What is the relationship between enthalpy of lattice dissociation and enthalpy of lattice
formation?
Ans: same numerical value but different signs
10). State hess' law
Ans: Enthalpy change for any chemical reaction is independent of the route taken, and
depends only on the initial and final states.
11). Why is the second electron affinity endothermic?
Ans: Repulsion of the negative ion with the negative electron being added
12). Define enthalpy of hydration
Ans: The enthalpy change when 1 mole of gaseous ions is converted to one mole of
aqueous ions
13). What does enthalpy of solution equal?
Ans: enthalpy of solution = lattice dissociation + enthalpy of hydration
(^H(solution)=^H(lattice dissociation)+^H(hydration))
14). What happens when and ionic compound dissolves in water?
Ans: the ionic lattice breaks up (enthalpy of lattice dissociation )
the polar water molecules form bonds with the ions (enthalpy of hydration)
15). Define enthalpy of solution
Ans: the enthalpy change when one mole of ionic compounds dissolves in water to
form a solution of infinite dilution
16). Why do some compounds have covalent character?
PaperStoc.com Page 2 of 5
QUESTIONS (35 TERMS) WITH VERIFIED
DEFINITIONS UPDATED 2024
1). Explain what is meant by the term co-ordinate bond
Ans: a covalent bond in which both electrons are donated by one atom
2). Define the term ligand
Ans: Atom, ion or molecule which can donate a pair of electrons to a metal ion
3). What can lattice enthalpy defined as? (2 things)
Ans: Lattice enthalpy of formation and lattice enthalpy of dissociation
4). Why is the experimental value for lattice dissociation of some compounds greater than the
theoretical value?
Ans: the bonding is not 100% ionic/ there is some covalent character/ there is
additional covalent bonding
5). What does the perfect ionic model assume?
Ans: The bonding in the compound is not 100% ionic. In the model the ions are perfect
spheres/point charges are not distorted
6). What 2 things might cause a different lattice enthalpy?
Ans: Enthalpy of bond dissociation (eg halogens)
Enthalpy of formation
7). Why is the lattice enthalpy greater for ions with a high charge?
Ans: There is a stronger attraction
Why is the lattice enthalpy greater for smaller ions?
PaperStoc.com Page 1 of 5
, 8).
Ans: smaller ions are more closely packed in the lattice
there is a stronger attraction
9). What is the relationship between enthalpy of lattice dissociation and enthalpy of lattice
formation?
Ans: same numerical value but different signs
10). State hess' law
Ans: Enthalpy change for any chemical reaction is independent of the route taken, and
depends only on the initial and final states.
11). Why is the second electron affinity endothermic?
Ans: Repulsion of the negative ion with the negative electron being added
12). Define enthalpy of hydration
Ans: The enthalpy change when 1 mole of gaseous ions is converted to one mole of
aqueous ions
13). What does enthalpy of solution equal?
Ans: enthalpy of solution = lattice dissociation + enthalpy of hydration
(^H(solution)=^H(lattice dissociation)+^H(hydration))
14). What happens when and ionic compound dissolves in water?
Ans: the ionic lattice breaks up (enthalpy of lattice dissociation )
the polar water molecules form bonds with the ions (enthalpy of hydration)
15). Define enthalpy of solution
Ans: the enthalpy change when one mole of ionic compounds dissolves in water to
form a solution of infinite dilution
16). Why do some compounds have covalent character?
PaperStoc.com Page 2 of 5
