Enthalpy defs

Question 1

LATTICE ENTHALPY

Answer 1

The enthalpy change that accompanies the formation of one mole of an ionic compound from its gaseous ions under standard conditions

Question 2

ENTHALPY CHANGE OF SOLUTION

Answer 2

The enthalpy change that takes place when one mole of a compound is completely dissolved in water under standard conditions

Question 3

ENTHALPY CHANGE OF HYDRATION

Answer 3

The enthalpy change that takes place when one mole of isolated gaseous ions is dissolved in water forming one mole of aqueous ions under standard conditions

Question 4

ENTHALPY CHANGE OF FORMATION

Answer 4

The enthalpy change that takes place when one mole of a compound is formed from its constituent elements in their standard states, under standard conditions

Question 5

FIRST IONISATION ENERGY

Answer 5

The enthalpy change accompanying the removal of one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions

Question 6

SECOND IONISATION ENERGY

Answer 6

The enthalpy change accompanying the removal of one electron from each ion in one mole of gaseous 1+ ions to form one mole of gaseous 2+ ions

Question 7

ENTHALPY CHANGE OF ATOMISATION

Answer 7

The enthalpy change that takes place when one mole of gaseous atoms forms from the element in its standard state

Question 8

FIRST ELECTRON AFFINITY

Answer 8

The enthalpy change accompanying the addition of one electron to each atom in one mole of gaseous atoms to form one mole of gaseous 1- ions

Question 9

SECOND ELECTRON AFFINITY

Answer 9

The enthalpy change accompanying the addition of one electron to each ion in one mole of gaseous 1- ions to form one mole of gaseous 2- ions

Question 10

ENTROPY, S

Answer 10

The quantitative measure of the degree of ‘disorder’ in a system

Question 11

FREE ENERGY CHANGE, ΔG

Answer 11

The balance between entropy, enthalpy and temperature for a process:

ΔG = ΔH – TΔS

A process can take place spontaneously when ΔG < 0 (when ΔG is –ve)