Thermodynamics Definitions

Question 1

Lattice formation enthalpy

Answer 1

The enthalpy change when one mole of a solid ionic compound is formed from its gaseous ions

Question 2

Enthalpy change of formation

Answer 2

The enthalpy change when one mole of a compound is formed from its elements in their standard states

Question 3

Bond dissociation enthalpy

Answer 3

The enthalpy change when all the bonds of the same type in one mole of gaseous molecules are broken

Question 4

Enthalpy change of atomisation of an element

Answer 4

The enthalpy change when one mole of gaseous atoms is formed from an element in its standard state

Question 5

Enthalpy change of atomisation of a compound

Answer 5

The enthalpy change when one mole of a compound in its standard state is converted to gaseous atoms

Question 6

First ionisation energy

Answer 6

The enthalpy change when one mole of gaseous 1+ ions is formed from one mole of gaseous atoms

Question 7

Lattice dissociation enthalpy

Answer 7

The enthalpy change when l 1 mole of a solid ionic compound is completely dissociated into its gaseous ions

Question 8

Second ionisation energy

Answer 8

The enthalpy change when 1 mole of gaseous 2+ ions is formed from 1 mole of gaseous 1+ ions

Question 9

First electron affinity

Answer 9

The enthalpy change when 1 mole of gaseous 1- ions is made from 1 mole of gaseous atoms

Question 10

Second electron affinity

Answer 10

The enthalpy change when 1 mole of gaseous 2- ions is made from 1 mole of gaseous 1- ions

Question 11

Enthalpy change of hydration

Answer 11

The enthalpy change when 1 mole of aqueous ions is formed from gaseous ions

Question 12

Enthalpy change of solution

Answer 12

The enthalpy change when 1 mole of an ionic substance dissolves in enough solvent to form an infinitely dilute solution

Question 13

Hess’s law

Answer 13

The total enthalpy change f a reaction is always the same, no matter which route is taken