Enthalpy and entropy

Question 1

Enthalpy change of reaction

Answer 1

Enthalpy change when the reactants in the stoichiometric equation react to give the products under standard conditions.

Question 2

Enthalpy change of formation

Answer 2

Enthalpy change when one mole of a compound is formed from its elements under standard conditions.

Question 3

Enthalpy change of combustion

Answer 3

Enthalpy change when one mole of a substance is burnt in excess oxygen under standard conditions.

Question 4

Enthalpy change of neutralization

Answer 4

Enthalpy change when one mole of water is formed by reacting an acid and an alkali under standard conditions.

Question 5

Average bond enthalpy

Answer 5

The energy required to break one mole of a specific bond in a gaseous molecule.

Question 6

Lattice enthalpy

Answer 6

Measure of the strength of the forces between the ions in an ionic solid

Question 7

Enthalpy change of atomisation

Answer 7

Enthalpy change when 1 mole of gaseous atoms is made from an element in its standard state.

Question 8

Lattice enthalpy change of formation

Answer 8

Enthalpy change when 1 mole of a solid ionic compound is formed from its gaseous ions

Question 9

1st electron affinity

Answer 9

Enthalpy change when 1 mole of gaseous 1- ions are made from 1 mole of gaseous atoms

Question 10

2nd electron affinity

Answer 10

Enthalpy change when 1 mole of gaseous 2- ions are made from 1 mole of gaseous 1- ions

Question 11

1st ionisation energy

Answer 11

1 mole of gaseous 1+ ions are made from 1 mole of gaseous atoms

Question 12

2nd ionisation energy

Answer 12

1 mole of gaseous 2+ ions are made from 1 mole of gaseous 1+ ions

Question 13

Enthalpy change of solution

Answer 13

Enthalpy change when 1 mole of an ionic substance is dissolved in the minimum amount of solvent to ensure no further enthalpy change is observed upon further dilution under standard conditions.

Question 14

Lattice dissocation enthalpy

Answer 14

Energy required to break up 1 mole of a solid lattice into its gaseous ions under standard conditions.

Question 15

Enthalpy change of hydration

Answer 15

Enthalpy change when 1 mole of gaseous ions is completely dissolved in water to infinite dilution

Question 16

Perfect ionic model

Answer 16

All ions are perfectly spherical
Charge evenly distributed
No covalent character- Charge dist uneven, polarisation of anion or cation