Part 1 Flashcards
Definition of enthalpy change of formation
The enthalpy change when one mole of a substance is formed from its element under standard conditions,with all substances in their standard states
Definition of enthalpy change 🔼h
The heat energy change at a constant pressure
Definition of the standard enthalpy of combustion 🔼 H
C
The enthalpy change when one mole of a substance is completely combusted in excess oxygen under standard conditions,with all substances in their states
Definition of mean bond enthalpy
🔼. H
BE
The enthalpy change when one mole of a given covalent bond is broken, averaged over a range of compounds
Define bond dissociation enthalpy
🔼. H
Diss
The enthalpy change to break the bond in one mole of gaseous molecules to form gaseous atoms
Define The standard enthalpy of atomisation ΔatHØ (ENDOTHERMIC)
The enthalpy change for the formation of one mole of gaseous atoms from the element in
its standard state.
Define First ionisation energy – Δ1st IEH (ENDOTHERMIC)
The enthalpy change when one mole of electrons is removed from one mole of gaseous
atoms to form one mole of gaseous 1+ ions.
Define First ionisation energy – Δ1st IEH (ENDOTHERMIC)
The enthalpy change when one mole of electrons is removed from one mole of gaseous
atoms to form one mole of gaseous 1+ ions.
Define Second ionisation energy – Δ2nd IEH (ENDOTHERMIC)
The enthalpy change when one mole of electrons is removed from one mole of gaseous 1+
ions to form one mole of gaseous 2+ ions.
Why is second ionisation of an atom greater than the first ?
It is more difficult to remove an electron from a more positive ion
Define The first electron affinity (EA) Δ1st EAH (EXOTHERMIC)
The enthalpy change when one mole of electrons is added to one mole of gaseous atoms to
form one mole of gaseous 1- ions.
Why is the first electron affinity exothermic?
Due to the attraction between the electron
Define The second electron affinity (EA) Δ2nd EAH (ENDOTHERMIC)
The enthalpy change when one mole of electrons is added to one mole of gaseous 1- ions,
to form one mole of gaseous 2- ions.
Why is the second electron affinity of any ion always endothermic?
Energy is required to overcome the repulsion between the negative electron and the negative ion
Define Lattice formation enthalpy ΔLFH (EXOTHERMIC)
The enthalpy change when one mole of a solid ionic compound is formed from its gaseous
ions.
