enthalpy definitions

Question 1

enthalpy of formation

Answer 1

enthalpy change when one mole of a substance is formed from its constituent elements with all substances in their standard states

Question 2

enthalpy of combustion

Answer 2

enthalpy change when one mole of a substance undergoes complete combustion in oxygen with all substances in their standard states

Question 3

enthalpy of neutralisation

Answer 3

enthalpy change when one mole of water is formed in a reaction between an acid an alkali under standard conditions

Question 4

first and second ionisation energy definitions

Answer 4

• first ionisation energy=enthalpy change when each atom in one mole of gaseous atoms loses one electron to form one mole of gaseous 1+ions
• second ionisation energy=enthalpy change when each ionin one mole of gaseous 1+ ions loses one electron to form one mole of gaseous 2+ ions

Question 5

first and second electron affinity energies

Answer 5

• first electron affinity=enthalpy change when each atom in one mole of gaseous atoms gains one electron to form one mole of gaseous 1- ions
• second electron affinity=enthalpy change when each ion in one mole of gaseous 1- ions gains one electron to form one mole of gaseous 2- ions

Question 6

enthalpy of atomisation

Answer 6

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

Question 7

hydration enthalpy definiton

Answer 7

enthalpy change when one mole of gaseous ions become hydrated

Question 8

enthalpy of solution

Answer 8

enthalpy change when one mole of an ionic solid dissolves in an amount of water large enough so that the dissolved ions are well separated and dont interact with each other

Question 9

bond dissociation enthalpy

Answer 9

enthalpy change when one mole of covalent bonds is broken in the gaseous state

Question 10

lattice enthalpy of formation

Answer 10

enthalpy change when one mole of a solid ionic compound is formed from its constituent ions in the gas phase

Question 11

lattice enthalpy of dissociation

Answer 11

enthalpy change when one mole of a solid ionic compound is broken up into its constituent ions in the gas phase

Question 12

enthalpy of vaporisation

Answer 12

enthalpy change when one mole of a liquid is turned into a gas

Question 13

enthalpy of fusion

Answer 13

enthalpy change when one mole of a solid is turned into a liquid