Topic 5 & 15

Question 1

Standard enthalpy change of a reaction

Answer 1

the enthalpy change when molar amounts of reactants react together under standard conditions to give products.

Question 2

Standard Enthalpy change of combustion

Answer 2

The enthalpy change when one mole of a substance is completely burnt in oxygen under standard conditions

Question 3

Standard state

Answer 3

the normal, most pure stable state of a substance measured at 100kPa

Question 4

Enthalpy change of neutralisation

Answer 4

The enthalpy change
when one mole of water molecules are formed when an acid (H+) reacts
with an alkali (OH−) under standard conditions

Question 5

Enthalpy change of solution

Answer 5

The enthalpy change when one mole of solute is dissolved in excess solvent to form a solution of ‘infinite dilution’ under standard conditions

Question 6

Standard enthalpy of formation

Answer 6

The enthalpy change when one mole of a substance is formed from its elements
in their standard states under standard conditions

Question 7

Bond enthalpy

Answer 7

The average amount of energy required to break one mole of covalent bonds, in gaseous molecules under standard conditions. ‘Average’ refers to the fact that the bond enthalpy is different per molecule, therefore the value is the average amount of energy to break a particular bond
in a range of molecules.

Question 8

Standard enthalpy change of atomisation

Answer 8

The enthalpy change when one mole of gaseous atoms is formed from an element under standard conditions

Question 9

First ionisation energy

Answer 9

The enthalpy change when one electron is removed from each atom in one mole of gaseous atoms
under standard conditions

Question 10

First electron affinity

Answer 10

The enthalpy change when one electron is added to each atom in one mole of gaseous atoms under
standard conditions

Question 11

Lattice enthalpy

Answer 11

The enthalpy change when one mole of an ionic compound is broken apart into its constituent gaseous ions under standard conditions.

Question 12

Enthalpy change of hydration

Answer 12

The enthalpy change when one mole of gaseous ions is surrounded by water molecules to form an ‘infinitely dilute
solution’ under standard conditions.

Question 13

Spontaneous reaction

Answer 13

Reaction that occurs without any outside
influence