Enthalpy definitions

Question 1

Enthalpy of formation

Answer 1

enthalpy change that occurs when one mole of a compound is formed from its elements

Question 2

Enthalpy of combustion

Answer 2

enthalpy change that occurs when one mole of a substance undergoes complete combustion in excess oxygen

Question 3

Enthalpy of bond dissociation

Answer 3

enthalpy change when one mole of covalent bonds in a gaseous molecule is broken to form gaseous atoms (free radicals)

Question 4

Enthalpy of atomisation

Answer 4

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

Question 5

1st ionisation energy

Answer 5

enthalpy change when one mole of gaseous atoms each loose one electron to produce one mole of gaseous 1+ ions and electrons

Question 6

1st electron affinity

Answer 6

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 7

Lattice enthalpy

Answer 7

enthalpy change that accompanies the formation of one mole of a solid ionic compound is formed from its consituent isolated gaseous ions under standard conditions

Question 8

Enthalpy of lattice dissociation

Answer 8

enthalpy change when one mole of a solid ionic compound is split into isolated gaseous ions

Question 9

Enthalpy of hydration

Answer 9

standard enthalpy change that takes place when one mole of isolated gaseous ions is dissolved in water to form one mole of aqueous ions

Question 10

Enthalpy of solution

Answer 10

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