Thermodynamics

Question 1

Enthalpy of formation

Answer 1

The enthalpy change when one mole of a substance is formed from the constituent elements with all substances in their standard states under standard conditions.

Question 2

Enthalpy of combustion

Answer 2

The enthalpy change when one mole of a substance undergoes complete combustion in oxygen with all substances in standard states under standard conditions.

Question 3

Enthalpy of neutralisation

Answer 3

The enthalpy change when 1 mole of water is formed in a reaction between an acid and alkali under standard conditions in.

Question 4

First ionisation energy

Answer 4

The enthalpy change when each atom in one mole of gaseous atoms loses one electron to form one mole of gaseous 1+ ions.

Question 5

Second ionisation energy

Answer 5

The enthalpy change when each ion in one mole of gaseous 1+ ions loses one electron to form one mole of gaseous 2+ ions.

Question 6

First electron affinity

Answer 6

The enthalpy change when each atom in one mole of gaseous atoms gains one electron to form one mole of gaseous 1- ions.

Question 7

Second electron affinity

Answer 7

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

Question 8

Enthalpy of atomisation

Answer 8

The enthalpy change when one mole of gaseous atoms is produced from an element in its standard state under standard conditions.

Question 9

Hydration enthalpy

Answer 9

The enthalpy change when one mole of gaseous ions becomes hydrated - dissolved in water.

Question 10

Enthalpy of solution

Answer 10

The enthalpy change when one mole of an ionic solid dissolves in an amount of water large enough so that the dissolved ions are well separated and do not interact with each other.

Question 11

Bond dissociation enthalpy

Answer 11

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

Question 12

Lattice enthalpy of formation

Answer 12

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

Question 13

Lattice enthalpy of dissociation

Answer 13

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

Question 14

Enthalpy of vaporisation

Answer 14

The enthalpy change when one mole of a liquid is turned into a gas.

Question 15

Enthalpy of fusion

Answer 15

The enthalpy change when one mole of a solid is turned into a liquid.

Question 16

Standard conditions

Answer 16

100kPa and a stated temperature - at 298K

Question 17

Mean bond enthalpy

Answer 17

The average enthalpy change when one mole of a bond is broken to give separated atoms in the gas state.

Question 18

What does entropy measure?

Answer 18

Randomness/disorder

Question 19

What happens to entropy as a liquid changes into a gas?

Answer 19

Large increase in entropy.

Question 20

What do Born-Haber cycles show?

Answer 20

Enthalpy changes for the formation of an ionic compound.