Enthalpy Definitions (Chemistry)

Question 1

Define: Enthalpy of Formation

Answer 1

Enthalpy change when 1 mole of substance is formed from its constituent elements with all substances in their standard states:

2Na(s) + 1/2 O2(g) –> Na2O(s)

Question 2

Define: Enthalpy of Combustion

Answer 2

Enthalpy change when 1 mole of substance undergoes complete combustion in oxygen with all substances in standard states

Question 3

Define: Enthalpy of neutralisation

Answer 3

Enthalpy change when 1 mole of water is formed in a reaction between an acid and alkali under standard conditions

Question 4

Define: First Ionisation Enthalpy

Answer 4

enthalpy change when each atom in one mole of gaseous atoms loses one electron to form one mole of gaseous 1+ ions

Question 5

Define: Second ionisation energy

Answer 5

enthalpy change when each ion in one mole of gaseous 1+ ions loses one electron to form one mole of gaseous 2+ ions

Question 6

Define: First Electron Affinity

Answer 6

enthalpy change when each atom in one mole of gaseous atoms gains one electron to form one mole of gaseous 1- ions

Question 7

Define Second Electron Affinity

Answer 7

enthalpy change when each atom in one mole of gaseous 1- ions gains one electron to form one mole of gaseous 2- ions

Question 8

Define: Enthalpy of atomisation

Answer 8

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

Question 9

Define: Hydration Enthalpy

Answer 9

Enthalpy change when one mole of gaseous ions becomes hydrated

Question 10

Define: Enthalpy of Solutions

Answer 10

Enthalpy change when one mole of solute is dissolved in a solvent

Question 11

Define: Bond Dissociation of Formation

Answer 11

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

Question 12

Define: Lattice Enthalpy of Formation

Answer 12

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

Question 13

Define: Lattice Enthalpy of Disassociation

Answer 13

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

Question 14

Define: Enthalpy of vaporisation

Answer 14

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

Question 15

Define: Enthalpy of Fusion

Answer 15

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

Question 16

Which enthalpy change has the symbol: f

Answer 16

formation

Question 17

Which enthalpy change has the symbol: c

Answer 17

combustion

Question 18

Which enthalpy change has the symbol: neut

Answer 18

neutralisation

Question 19

Which enthalpy change has the symbol: ie

Answer 19

Ionisation

Question 20

Which enthalpy change has the symbol: ea

Answer 20

electron affinity

Question 21

Which enthalpy change has the symbol: at

Answer 21

atomisation

Question 22

Which enthalpy change has the symbol: hyd

Answer 22

hydration

Question 23

Which enthalpy change has the symbol: sol

Answer 23

solution

Question 24

Which enthalpy change has the symbol: dis

Answer 24

bond dissociation

Question 25

Which enthalpy change has the symbol: LEF

Answer 25

lattice formation

Question 26

Which enthalpy change has the symbol: LED

Answer 26

lattice dissociation

Question 27

Which enthalpy change has the symbol: vap

Answer 27

vaporisation

Question 28

Which enthalpy change has the symbol: fus

Answer 28

fusion

Question 29

Define: Average Bond Enthalpy

Answer 29

the energy needed to break one mole of a given bond in a gaseous molecule

Question 30

Define: first ionisation energy

Answer 30

the energy required for the removal of 1 mol of electrons from 1 mol of gaseous atoms

Question 31

Define: Activation energy

Answer 31

the energy required to break bonds that act as a barrier to a reaction

Question 32

Define: Enthalpy of Reaction

Answer 32

the enthalpy change that accompanies a reaction in the molar quantities as shown in a chemical equation at STC and STS

Question 33

Which enthalpy change has the symbol: r

Answer 33

reaction