Chapter 22

Question 1

Enthalpy of atomisation

Answer 1

The enthalpy of atomisation of an element is the enthalpy change
when 1 mole of gaseous atoms is formed from the element in its standard state

Question 2

Enthalpy of sublimation will be the same as

Answer 2

the enthalpy of atomisation

Question 3

First Ionisation enthalpy

Answer 3

enthalpy change required to remove 1 mole of electrons from 1 mole
of gaseous atoms to form 1 mole of gaseous ions with a +1 charge

Question 4

Second Ionisation enthalpy

Answer 4

enthalpy change to remove 1 mole of electrons from one mole
of gaseous 1+ ions to produces one mole of gaseous 2+ ions.

Question 5

First Ionisation enthalpy example

Answer 5

Mg (g) -> Mg+(g) + e-

Question 6

Second Ionisation enthalpy example

Answer 6

Mg+(g) -> Mg 2+ (g) + e-

Question 7

First Electron affinity

Answer 7

enthalpy change that occurs when 1 mole of gaseous atoms gain 1 mole of electrons to form 1 mole of gaseous ions with a 1-
charge

Question 8

First Electron affinity example

Answer 8

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

Question 9

second electron affinity

Answer 9

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

Question 10

second electron affinity example

Answer 10

O –(g) + e- -> O2- (g)

Question 11

The Lattice Enthalpy is the

Answer 11

standard enthalpy change when 1 mole of an ionic crystal lattice is formed from its constituent ions in gaseous form.

Question 12

lattice enthalpy and enthalpy of solution example

Answer 12

lattice: Na+(g) + Cl- (g) -> NaCl (s)
solution: NaCl (s) + aq -> Na+(aq) + Cl-(aq)

Question 13

Enthalpy of Hydration

Answer 13

Enthalpy change when one mole of gaseous ions become 1 mole of aqueous ions

Question 14

Enthalpy of Hydration EXAMPLE

Answer 14

X+(g) + aq -> X+(aq)
OR
X-(g) + aq ->X- (aq)

Question 15

enthalpy change of solution

Answer 15

enthalpy change when 1 mole of solute dissolves completely in a solvent, water

Question 16

Enthalpy of Hydration IS ALWAYS

Answer 16

exothermic because bonds are formed

Question 17

first electron affinity is exothermic for atoms that usually form 1- ions because

Answer 17

ion is more stable than atom
nuclear attraction between nucleus and electron

Question 18

endo or exo?

second electron affinity is

Answer 18

endothermic because it takes energy to overcome the repulsive force between the negative ion and electron (double negative, like charges repel)

Question 19

enthalpy change of atomisation is always

Answer 19

endothermic

Question 20

lattice enthalpy depends on…. and is always a…

Answer 20

the strength of the ionic bonding
it is always large and negative

Question 21

The strength of a enthalpy of lattice formation depends on…

Answer 21

sizes of the ion
charges on the ion

Question 22

sizes of ion on strength of LE

Answer 22

larger ions=less negative LE.
charges become further apart so have weaker forces of attraction.

Question 23

charges on ion on strength of LE

Answer 23

bigger charge= greater attraction between ions= larger LE(more negative value)

Question 24

The lattice enthalpies become

Answer 24

less negative down any group

Question 25

if the magnitude of lattice enthalpy is less than the sum, the enthalpy is

Answer 25

exothermic and therefore soluble

Question 26

entropy

Answer 26

measure of the dispersal of energy and disorder within the chemicals making up the chemical system

Question 27

entropy symbol and units

Answer 27

s jk-1mol-1

Question 28

entropy has a natural tendency to spread so

Answer 28

greater dispersal=greater disorder

Question 29

trend in entropy- states

Answer 29

solid->liquid->gas increasing entropy

Question 30

entropy mole ratios 4 vs 2 moles

Answer 30

decrease in randomness, energy less spread out so entropy change is negative

Question 31

standard entropy

Answer 31

entropy of one mole of the substance under standard conditions, value always positive

Question 32

free energy change

Answer 32

represents overall change in energy in a chemical reaction, taking into account the enthalpy change and the dispersal of energy

Question 33

gibbs equation

Answer 33

ΔG = ΔH - TΔS

Question 34

if ΔG is negative, the reaction is

Answer 34

energetically feasible/spontaneous

Question 35

why is reaction not always feasible?

Answer 35

no account into rate and Ea is so high it wont take place as it is too slow

Question 36

limitations of gibbs

Answer 36

some do not take place even when feasible like diamond to graphite

Question 37

∆S :

Answer 37

˚ = Σ S˚products - ΣS˚reactants