Thermodynamics

Question 1

Enthalpy of Formation

Answer 1

The standard enthalpy change of formation of a compound is the energy transferred when 1 mole of
the compound is formed from its elements under standard conditions (298 K and 100 kpa), all
reactants and products being in their standard states

Question 2

1st Ionisation Energy

Answer 2

The first ionisation enthalpy is the enthalpy change required to remove 1 mole of electrons from 1 mole of gaseous atoms to form 1 mole of gaseous ions with a +1 charge

Question 3

2nd Ionisation Energy

Answer 3

The second ionisation enthalpy is the enthalpy change to remove 1 mole of electrons from one mole of gaseous 1+ ions to produces one mole of gaseous 2+ ions.

Question 4

Enthalpy of Atomisation

Answer 4

The enthalpy of atomisation of an element is the enthalpy change when 1 mole of gaseous atoms is formed from the element in its standard state

Question 5

Bond Enthalpy

Answer 5

The bond dissociation enthalpy is the standard molar enthalpy change when one mole of a covalent bond is broken into two gaseous atoms (or free radicals)

Question 6

1st Electron Affinity

Answer 6

The first electron affinity is the enthalpy change that occurs when 1 mole of gaseous atoms gain 1 mole of electrons to form 1 mole of gaseous ions with a –1 charge

Question 7

2nd Electron Affinity

Answer 7

The second electron affinity is the enthalpy change when one mole of gaseous 1- ions gains one electron per ion to produce gaseous 2- ions

Question 8

Enthalpy of Hydration

Answer 8

Enthalpy change when one mole of gaseous ions become aqueous ions

Always gives out energy (exothermic, -ve) because bonds are
made between the ions and the water molecules.

Question 9

Enthalpy of Lattice Formation

Answer 9

The enthalpy of lattice formation is the standard enthalpy change when 1 mole of an ionic crystal lattice is formed from its constituent ions in gaseous form.

Question 10

Enthalpy of Lattice Dissociation

Answer 10

The enthalpy of lattice dissociation is the standard enthalpy change when 1 mole of an ionic crystal lattice form is separated
into its constituent ions in gaseous form.

Question 11

Enthalpy of Solution

Answer 11

The enthalpy of solution is the standard enthalpy change when one mole of an ionic solid dissolves in a large enough amount of water to ensure that the dissolved ions are well separated and do not interact with one another.