Enthalpy Change Definitions

Question 1

Lattice enthalpy

Answer 1

Enthalpy change when one mole of a solid lattice is made from it gaseous ions under standard conditions
(Exothermic)
K+(g) + Cl-(g) -> KCl (s)

Question 2

Standard Enthalpy Change of Atomisation

Answer 2

1 mole of gaseous atoms made from its elements in standard state
(Endothermic)
K(s)-> K(g)

Question 3

First Ionisation Energy

Answer 3

One mole of gaseous 1+ ions formed from gaseous atoms
(Endothermic)
K(g)-> K+(g) +e-

Question 4

Second ionisation energy

Answer 4

One gaseous mole of 2+ ions formed from gaseous 1+ ions
Endothermic
K+ -> K+2 + e-

Question 5

First Electron Affinity

Answer 5

One mole of gaseous 1- ions formed from gaseous atoms
Exothermic
Cl(g) + e- -> Cl- (g)

Question 6

Second Electron Affinity

Answer 6

One mole of gaseous 2- ions made from gaseous -1 ions
Exothermic
Cl-(g) + e- -> Cl2- (g)

Question 7

Standard Enthalpy of Solution

Answer 7

One mole of solid dissolved water to form aq ions
(Exo or endo)
KCl(s) + aq -> K+(aq) + Cl-(aq)

Question 8

Standard Enthalpy of Hydration

Answer 8

One mole of gaseous ions dissolved to form one mole of aq ions
Exothermic
K+ (g) + aq-> K+ (aq)