Chapter 17: Thermodynamics

Question 1

Bond Dissociation Enthalpy

Answer 1

The enthalpy change for breaking 1 mole of bonds in 1 mole of gaseous molecules.

Question 2

What type of process is bond dissociation enthalpy?

Answer 2

Endothermic

Question 3

Example of bond dissociation enthalpy reaction

Answer 3

Cl2 (g) -> Cl (g) + Cl (g)

Question 4

Standard Enthalpy of Formation

Answer 4

Enthalpy change when 1 mole of a substance is formed from its elements under standard conditions (298K and 100kPa), with all substances being in their standard states.

Question 5

What type of process is standard enthalpy of formation?

Answer 5

Exothermic

Question 6

Example of standard enthalpy of formation reaction

Answer 6

C (s, graphite) + 2H2 (g) -> CH4 (g)

Question 7

Enthalpy of Atomization

Answer 7

Enthalpy change when 1 mole of gaseous atoms of a substance are formed from the substance in its standard state under standard conditions (298K and 100kPa).

Question 8

What type of process is enthalpy of atomization?

Answer 8

Endothermic

Question 9

Example of enthalpy of atomization reaction

Answer 9

1/2 Cl2 (g) -> Cl (g)

Question 10

Ionization Enthalpy

Answer 10

Enthalpy change for the conversion of 1 mole of gaseous atoms to 1 mole of gaseous cations, each atom losing an electron.

Question 11

What type of process is ionization enthalpy?

Answer 11

Endothermic

Question 12

Example of ionization enthalpy reaction

Answer 12

Na (g) -> Na+ (g) + e-

Question 13

Second Ionization Enthalpy

Answer 13

Involves the removal of a second electron from the gaseous cation.

Question 14

What type of process is second ionization enthalpy?

Answer 14

Endothermic

Question 15

Example of second ionization enthalpy reaction

Answer 15

Na+ (g) -> Na2+ (g) + e-

Question 16

Enthalpy of Electron Affinity

Answer 16

Enthalpy change for the conversion of 1 mole of gaseous atoms into 1 mole of gaseous anions, each atom gaining an electron.

Question 17

What type of process is enthalpy of electron affinity?

Answer 17

Exothermic

Question 18

Example of enthalpy of electron affinity reaction

Answer 18

Cl (g) + e- -> Cl- (g)

Question 19

Second Electron Affinity

Answer 19

Enthalpy change for the conversion of 1 mole of gaseous 1- ions to 1 mole of gaseous 2- ions by gaining one electron.

Question 20

What type of process is second electron affinity?

Answer 20

Endothermic

Question 21

Example of second electron affinity reaction

Answer 21

O- (g) + e- -> O2- (g)

Question 22

Lattice Formation Enthalpy

Answer 22

Enthalpy change for the formation of 1 mole of solid ionic compound from its constituent gaseous ions.

Question 23

What type of reaction is lattice formation enthalpy?

Answer 23

Exothermic

Question 24

Example of lattice formation enthalpy reaction

Answer 24

Na+ (g) + Cl- (g) -> NaCl (s)

Question 25

Lattice Dissociation Enthalpy

Answer 25

Enthalpy change when 1 mole of an ionic lattice dissociates into isolated gaseous ions.

Question 26

What type of process is lattice dissociation enthalpy?

Answer 26

Endothermic

Question 27

Example of lattice dissociation enthalpy reaction

Answer 27

NaCl (s) -> Na+ (g) + Cl- (g)

Question 28

Enthalpy of Solution

Answer 28

Enthalpy change when 1 mole of an ionic compound is dissolved in water to produce aqueous ions in its standard state under standard conditions.

Question 29

Stage 1 of Enthalpy of Solution

Answer 29

Separating the ions in the crystal- lattice dissociation enthalpy

Question 30

What type of process is stage 1 of enthalpy of solution?

Answer 30

Endothermic because energy is required to overcome attractive forces between the ions.

Question 31

Stage 2 of Enthalpy of Solution

Answer 31

Hydration of ions- the ions form bonds with the H2O molecules

Question 32

Standard Enthalpy of Hydration

Answer 32

Enthalpy change when 1 mole of gaseous ions is converted to 1 mole of aqueous ions in its standard state under standard conditions.

Question 33

What type of reaction is standard enthalpy of hydration?

Answer 33

Exothermic

Question 34

Example of standard enthalpy of hydration reaction

Answer 34

Na+ (g) -> Na+ (aq)

Question 35

Mean Bond Enthalpy

Answer 35

Average enthalpy change for breaking 1 mole of a particular bond in a range of different compounds in the gas phase.

Question 36

What type of process is mean bond enthalpy?

Answer 36

Endothermic

Question 37

Steps of Constructing a Born-Haber Cycle

Answer 37

``` Step 1: atomisation of the metal Step 2: atomisation of the non-metal Step 3: ionisation of the metal Step 4: electron affinity of the non-metal Step 5: formation of the lattice ```