3.1.8 Thermodynamics

Question 1

Define enthalpy of formation Δ_fH^Θ

Answer 1

The enthalpy change when one mole of compound is formed from its elements when all reactants and products are in their standard states under standard conditions.

Question 2

Define enthalpy of lattice formation Δ_lattH^Θ

Answer 2

The enthalpy change when one mole of an ionic compound is formed from its constituent ions in the gaseous state.

Question 3

Define enthalpy of lattice dissociation Δ_lattH^Θ

Answer 3

The enthalpy change when one mole of an ionic compound is separated into its component gaseous ions.

Question 4

Define bond dissociation enthalpy Δ_disH^Θ

Answer 4

The enthalpy change when one mole of a covalent bond is broken under standard conditions in the gaseous state.

Question 5

Define enthalpy of atomisation of an element Δ_atH^Θ

Answer 5

The enthalpy change for the formation of one mole of gaseous atoms from the element in its standard state.

Question 6

Define first ionisation enthalpy Δ_IE1H^Θ

Answer 6

The enthalpy change when one mole of electrons is removed from one mole of gaseous atoms to form one mole of gaseous ions with a single positive charge.

Question 7

Define second ionisation enthalpy Δ_IE2H^Θ

Answer 7

The enthalpy change when one mole of electrons is removed from one mole of gaseous ions with a single positive charge to form one mole of gaseous ions with a 2+ charge.

Question 8

Define third ionisation enthalpy Δ_IE3H^Θ

Answer 8

The enthalpy change when one mole of electrons is removed from one mole of gaseous ions with a 2+ charge to form one mole of gaseous ions with a 3+ charge.

Question 9

Define first electron affinity
Δ_EA1H^Θ

Answer 9

The enthalpy change when one mole of gaseous atoms forms one mole of negative ions with a single negative charge.

Question 10

Define second electron affinity
Δ_EA2H^Θ

Answer 10

The enthalpy change when one mole of gaseous ions with a single negative charge forms one mole of gaseous ions with a double negative charge.

Question 11

Define enthalpy of hydration
ΔH_hyd^Θ

Answer 11

The enthalpy change when one mole of separated gaseous ions is dissolved in water to form one mole of aqueous ions.

Question 12

Define enthalpy of solution
ΔH_soln^Θ

Answer 12

The enthalpy change when one mole of an ionic substance is dissolved in a volume of water large enough to ensure that the ions are separated and do not interact with each other.