Thermodynamics

Question 1

Define enthalpy change of formation

Answer 1

Enthalpy change when one mole of a substance is formed from its constituent elements with all substance in their substances
-exothermic

Question 2

Define enthalpy change of combustion

Answer 2

Enthalpy change when one mole of a substance undergoes complete combustion in oxygen with all substances in standard states
-exothermic

Question 3

Define enthalpy of neutralisation

Answer 3

enthalpy change when 1 mole of water is formed in a reaction between an acid and alkali under standards conditions
-exothermic

Question 4

Define 1st ionisation enthalpy

Answer 4

Enthalpy change when each atom in one mole of gaseous atoms loses one electron to form one mole of gaseous 1+ ions
-endothermic

Question 5

Define 2nd ionisation energy

Answer 5

Enthalpy change when each ion in one mole of gaseous 1+ ions loses one electron to form one mole of gaseous 2+ ions
-endothermic

Question 6

Define 1st electron affinity

Answer 6

Enthalpy change when each atom in one mole of gaseous atoms gains one electron to form one mole of gaseous 1-ions
exothermic

Question 7

Define 2nd electron affinity

Answer 7

Enthalpy change when each ion in one mole of gaseous ions gains one electron to form one mole of gaseous 2- ions
endothermic

Question 8

Define enthalpy change of atomisation

Answer 8

Enthalpy change when one mole of gaseous atoms is produced from an element in its standard state
-endothermic

Question 9

Define hydration enthalpy

Answer 9

Enthalpy change when one mole of gaseous ions become hydrated(dissolved in water)
-exothermic

Question 10

Define enthalpy of solution

Answer 10

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
exothermic/endothermic

Question 11

Define bond dissociation enthalpy

Answer 11

Enthalpy change when one mole of covalent bond is broken in the gaseous state
-endothermic

Question 12

Define lattice enthalpy of formation

Answer 12

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

Question 13

Define lattice enthalpy of disassociation

Answer 13

Enthalpy change when one mole of a solid ionic compound is broken up into its constituent ions is the gas phase
endothermic

Question 14

Enthalpy change of vaporisation

Answer 14

Enthalpy change when one mole of a liquid is turned into a gas
endothermic

Question 15

Define enthalpy of fusion

Answer 15

Enthalpy change when one mole of a solid is turned into a liquid
endothermic

Question 16

Define bond enthalpy

Answer 16

Mean value across a range of compounds containing that bond

Question 17

Define enthalpy change

Answer 17

The heat change measured under conditions of constant pressure

Question 18

Define standard conditions

Answer 18

100kPa and stated temp. (eg 298K)