Thermodynamics

Question 1

Define enthalpy of formation:

Answer 1

Enthalpy change when one mole of a substance is formed from its constituent elements with all substances in their standard states. Exothermic

Question 2

Define enthalpy of combustion:

Answer 2

Enthalpy change when one mole of a substance undergoes combustion in oxygen with all substances in their standard states. Exothermic

Question 3

Define enthalpy of neutralisation

Answer 3

Enthalpy change when one mole of water is formed in a reaction between acid and alkali under standard conditions. Exothermic

Question 4

Define ionisation energy:

Answer 4

Enthalpy change when one mole of gaseous atoms/ (n-1) ions loses one mole of electrons to form one mole of gaseous n+ ions. Endothermic

Question 5

Define electron affinity:

Answer 5

Enthalpy change when one mole of gaseous atoms/ n+ ions gains one electron to form gaseous n-1 ions

Question 6

Define enthalpy of atomisation:

Answer 6

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

Question 7

Define hydration enthalpy:

Answer 7

Enthalpy change when one mole of gaseous ions become hydrated (dissolved in water). Exothermic

Question 8

Define enthalpy of solution:

Answer 8

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

Question 9

Define bind dissociation energy:

Answer 9

Enthalpy change when one mole of covalent bonds is broken in a gaseous state. Endothermic

Question 10

Define lattice enthalpy of formation:

Answer 10

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

Question 11

Define lattice enthalpy of dissociation:

Answer 11

Enthalpy change when one mole of solid ionic compound is broken up into its constituent ions in the gaseous phase. Endothermic

Question 12

Define enthalpy of vaporisation

Answer 12

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

Question 13

Define enthalpy of fusion:

Answer 13

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