Enthalpy defs

Question 1

Standard enthalpy change of formation

Answer 1

Enthalpy change when one mole of a compound is formed from its elements in their standard states, under standard conditions

Question 2

Standard enthalpy change of combustion

Answer 2

Enthalpy change when one mole of a compound is burned completely in oxygen under standard conditions

Question 3

Enthalpy change of lattice dissociation

Answer 3

Enthalpy change needed to convert one mole of a crystal into its constituent gaseous ions (always +)

Question 4

Enthalpy change of lattice formation

Answer 4

Enthalpy change when one mole of solid crystal is formed from its gaseous ions (always -)

Question 5

Standard enthalpy change of atomisation

Answer 5

Enthalpy change when one mole of gaseous atoms is formed from an element in its standard state (always +)

Question 6

Enthalpy change of solution

Answer 6

Enthalpy change when one mole of an ionic substance dissolves in water to form an infinitely dilute solution

Question 7

Enthalpy change of hydration

Answer 7

Enthalpy change when one mole of gaseous ions dissolve in water to form an infinitely dilute solution (always -)

Question 8

Standard enthalpy change of neutralisation

Answer 8

Enthalpy change when an acid and alkali solution react together under standard conditions to produce one mole of water

Question 9

Enthalpy change of ionisation

Answer 9

Enthalpy change when one mole of electrons is removed from one mole of gaseous atoms, producing one mole of gaseous 1+ ions

Question 10

Enthalpy of electron affinity

Answer 10

Enthalpy change when one mole of electrons is added to one mole of gaseous atoms, forming one mole of gaseous 1- ions