Aqa A-Level Chemistry Paper 1 Already Passed

Why is the phrase 'infinitely separated' used in enthalpy of lattice dissociation {Ans: all bonding in the ions must be broken}what is the relationship between enthalpy of lattice dissociation and enthalpy of lattice formation? {Ans: same numerical value but different signs}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}What 2 things might cause a different lattice enthalpy? {Ans: Enthalpy of bond dissociation (eg halogens) Enthalpy of formation}Define enthalpy of formation {Ans: Enthalpy change when 1 mole of a substance is formed from its constituent elements under standard conditions (all reactants and products in standard states).}Define mean bond enthalpy {Ans: the energy required to break one mole of covalent bond averaged over compounds containing that bond. (kJmol-1)}Which Enthalpy Changes are Endothermic? {Ans: enthalpy of lattice dissociation enthalpy of atomisation 1st/2nd ionisation enthalpy 2nd electron affinity bond dissociation enthalpy}why do some compounds have covalent character? {Ans: one of the ions is small and has a large charge this distorts the other ion the ions are not spherical}What can lattice enthalpy