energy 2 Flashcards
lattice enthalpy definition
the enthalpy change when one mole of ionic compounds is formed from its constituents in their gaseous states under standard conditions
electron affinity definition
the energy when one mole of gaseous atoms gains one mole of electrons to form one mole of gaseous 1- ions
(ALWAYS EXOTHERMIC), but successive electron affinities are endothermic as energy is required to overcome the electron repulsion
factors affecting lattice enthalpy
smaller ionic radius = more exothermic LE
higher change density = more exothermic LE
greater charge and greater radius
standard enthalpy change of formation
the enthalpy change when one mole of a compound is formed in its standard state from elements in their standard states under standard conditions
ionisation energy
energy required to remove one mole of gaseous electrons to form one mole of gaseous 1+ ions (ALWAYS ENDOTHERMIC)
standard enthalpy of atomisation
enthalpy change when one mole of gaseous atoms is formed in its standard state from its elements in their standard states under standard conditions (ALWAYS ENDOTHERMIC)
BORN HABER CYCLE LAYOUT
4 ^ 5/
3^
2^ 6/
1/
1= enthalpy of formation
2= enthalpy of atomisation
3= enthalpy of atomisation
4= first ionisation energy (1+)
5= first electron affinity (1-)
6= lattice enthalpy
Gets split into elements. Elements are made gaseous and singular moles. One element made +ve and the other -ve. Gaseous ions combined.
entropy definition
a measure of the degree of disorder in a system
increase disorder =
increase entropy
equation for standard entropy change
change = change in products - change in reactants
negative G
reaction is spontaneous
zero G
reaction is at equilibrium
change in S
total entropy change (JK-1mol-1)
change in H
enthalpy change (kJmol-1)
T
temperature of reaction (K)
