3.1.8 Thermodynamics (A- Level only)

Question 1

Enthalpy change of formation [definition]:

Answer 1

The energy transferred when 1 mole of the compound is formed from its elements under standard conditions in their standard states

Question 2

Lattice enthalpy [definition]:

Answer 2

Lattice enthalpy can be defined as either enthalpy of lattice dissociation or enthalpy of lattice formation

Question 3

Enthalpy of atomisation [definition]:

Answer 3

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

Question 4

First Ionisation energy [definition]:

Answer 4

The 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 5

Second ionisation energy [definition]:

Answer 5

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

Question 6

First electron affinitiy [definition]:

Answer 6

The first electron affinity is the 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 7

Is the first electron affinity exothermic? [2]:

Answer 7

• first electron affinity is exo for atoms that normally form negative ions.
• cus the ion is more stable than the atom, and there is an attraction between the nucleus and the electron.

Question 8

Second electron affinity [definition]:

Answer 8

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

Question 9

Is the second electron affinity exothermic? [2]:

Answer 9

• The second electron affinity for oxygen is endo

- cus it takes energy to overcome the repulsive force between the negative ion and the electron