Year 13 - Thermodynamics Definitions

Question 1

Define the standard enthalpy of formation.

Answer 1

The standard molar enthalpy of formation is the enthalpy change when one mole of a compound is formed from its constituent elements under standard conditions, all reactants and products in their standard states.

Question 2

Define the standard molar enthalpy change of combustion.

Answer 2

The standard molar enthalpy change is combustion is the enthalpy change when one mole of a substance is completely burnt in oxygen.

Question 3

Define the standard enthalpy of atomisation.

Answer 3

The standard enthalpy of atomisation is the enthalpy change which accompanies the formation of one mole of gaseous atoms from the element in its standard state under standard conditions.

Question 4

Define the first ionisation energy.

Answer 4

First ionisation energy is the standard enthalpy change when one mole of gaseous atoms is converted into a mole of gaseous ions each with a single positive charge.

Question 5

Define the first electron affinity.

Answer 5

The first electron affinity is the standard enthalpy change when a mole of gaseous atoms is converted to a mole of gaseous ions, each with a single negative charge.

Question 6

Define lattice enthalpy of formation.

Answer 6

Lattice enthalpy of formation is the standard enthalpy change when one mole of solid ionic compound is formed from its gaseous ions.

Question 7

Define lattice enthalpy of dissociation.

Answer 7

Lattice enthalpy of dissociation is the standard enthalpy change when one mole of solid ionic compound is dissociated into its gaseous ions.

Question 8

Define enthalpy of hydration.

Answer 8

Enthalpy of hydration is the standard enthalpy change when water molecule surround one mole of gaseous ions.

Question 9

Define enthalpy of solution.

Answer 9

Enthalpy of solution is the standard enthalpy change when one mole of solute dissolves completely in sufficient solvent to form a solution in which the molecules or ions are far enough apart to not interact with each other.

Question 10

Define mean bond enthalpy.

Answer 10

Mean bond enthalpy is the enthalpy change when one mole of gaseous molecules each breaks a covalent bond to form two free radicals, averaged over a range of compounds.