5.2.1 Lattice Enthalpy Flashcards
lattice enthalpy
formation of 1 mol of an ionic lattice from its gaseous ions
what can lattice enthalpy be used to measure
the strength of ionic bonding in a giant ionic lattice
what energy cycle must you use to determine lattice enthalpy indirectly (as it cannot be measured directly)
Born-Haber cycle
What are the key enthalpy changes involved in a Born-Haber cycle?
enthalpy change of formation
enthalpy change of atomisation
first ionisation energy
first electron affinity
first ionisation energy
removal of 1 mol of electrons from 1 mol of gaseous atoms
enthalpy change of formation
formation of 1 mol of a compound from its elements in their standard states
enthalpy change of hydration
dissolving 1 mol of gaseous ions in water
enthalpy change of solution
dissolving 1 mol of solute
is lattice enthalpy exothermic or endothermic?
exothermic
formation of bonds
is enthalpy change of atomisation exothermic or endothermic?
endothermic
bonds are broken when you form gaseous atoms
is first ionisation energy exothermic or endothermic?
endothermic
energy is required to overcome the attraction between a negative electron and a positive nucleus and form 1+ ions
is first electron affinity exothermic or endothermic?
exothermic
the electron being added is attracted to the nucleus
is second electron affinity exothermic or endothermic?
endothermic
you’re adding an electron to a negative ion, so energy must be put in to overcome the repulsion
what are the two factors that affect lattice enthalpy?
- ionic radius
- ionic charge
to give a maximum lattice enthalpy, you want
………… ionic radius
………… ionic charge
small
large
