Thermodynamics Definition

Question 1

Enthalpy of Formation

Answer 1

The enthalpy change required to form one mole of a substance from its constituent elements under standard conditions in standard states

Question 2

Enthalpy of Combustion

Answer 2

The enthalpy change required to completely burn one mole of a substance in the presence of oxygen, with all substances in their standard states

Question 3

First Ionisation Enthalpy

Answer 3

The enthalpy change when one mole of gaseous atoms loses one electron per atom to produce gaseous +1 ions

Question 4

Second Ionisation Enthalpy

Answer 4

The enthalpy change when one mole of gaseous +2 ions are formed from one mole of +1 ions

Question 5

First Electron Affinity

Answer 5

The enthalpy change when one mole of gaseous atoms gains one electron per atom to produce gaseous -1 ions

Question 6

Second Electron Affinity

Answer 6

The enthalpy change when one mole of gaseous -1 ions gains one electron per ion to form gaseous -2 ions

Question 7

Enthalpy of Atomisation

Answer 7

The enthalpy change when one mole of gaseous atoms are produced from an element in its normal state

Question 8

Hydration Enthalpy

Answer 8

The enthalpy change when one mole of gaseous ions become one mole of aqueous ions (dissolved in water)

Question 9

Enthalpy of Solution

Answer 9

The enthalpy change when one mole of an ionic solid dissolves in an amount of water large enough so that the dissolved ions are far apart enough to not interact with one another

Question 10

Bond Dissociation Enthalpy

Answer 10

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

Question 11

Lattice Enthalpy of Formation

Answer 11

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

Question 12

Lattice Enthalpy of Dissociation

Answer 12

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

Question 13

Hess’s Law

Answer 13

the enthalpy change of a chemical reaction is independent of the route taken

Question 14

Positive

Answer 14

• Enthalpy of atomisation
• Ionisation enthalpies
• Enthalpy of vapourisation
• Second electron affinity
• Lattice enthalpy of dissociation

Question 15

Negative

Answer 15

• First electron affinity
• Lattice enthalpy of formation
• Enthalpy change of reaction

Question 16

M (s) –> M (g)

Answer 16

enthalpy of atomisation of a metal

Question 17

1/2 X2 –> X (g)

Answer 17

enthalpy of atomisation of a diatomic

Question 18

Cl2 –> 2 Cl (g)

Answer 18

Bond dissociation enthalpy of chlorine

Question 19

Na+ (g) + Cl- (g) –> NaCl (s)

Answer 19

Formation lattice enthalpy of sodium chloride

Question 20

NaCl(s) –> Na+ (g) + Cl- (g)

Answer 20

Dissociation lattice enthalpy of sodium chloride

Question 21

CH3CH2OH (l) + 3O2 (g) –> 2CO2 (g) + 3H2O (l)

Answer 21

enthalpy of combustion of ethanol

Question 22

X (g) –> X+ (g) + e-

Answer 22

1st ionisation enthalpy

Question 23

X+ (g) –> X2+ (g) + e-

Answer 23

2nd ionisation enthalpy

Question 24

X (g) + e- –> X- (g)

Answer 24

1st electron affinity

Question 25

X- (g) + e- –> X2- (g)

Answer 25

2nd electron affinity