22C

Question 1

What is enthalpy of lattice formation?

Answer 1

The enthalpy change when one mole of an ionic compound is formed from its constituent ions in the gaseous state
it is exothermic

Question 2

What is enthalpy of lattice dissociation

Answer 2

The enthalpy change when one mole of an ionic compound is separated into its component gaseous ions
It is endothermic

Question 3

What is the enthalpy of atomisation of an element?

Answer 3

The enthalpy change for the formation of one mole of gaseous atoms from the element in its standard state.

Question 4

What is bond dissociation energy?

Answer 4

The enthalpy change when one mole of a covalent bond is broken under standard conditions in the gaseous state. It is endothermic.

Question 5

What is first ionisation enthalpy?

Answer 5

Enthalpy change when one mole of electrons is removed from one mole of gaseous atoms to form one mole of gaseous ions with a single positive charge.

Question 6

What is second ionisation enthalpy?

Answer 6

Enthalpy change when one mole of electrons is removed from one mole of gaseous ions with a single positive charge to form one mole of gaseous ions with a 2+ charge.

Question 7

What is third ionisation enthalpy?

Answer 7

Enthalpy change when one mole of electrons is removed from one mole of gaseous ions with a 2+ charge to form one mole of gaseous ions with a 3+ charge.

Question 8

What is first electron affinity?

Answer 8

The enthalpy change when one mole of gaseous atoms forms one mole of gaseous ions with a single negative charge.

Question 9

What is second electron affinity?

Answer 9

• The enthalpy change when one mole of gaseous ions with a single negative charge forms one mole of gaseous ions with a double negative charge.
• Second electron affinity value is positive, therefore endothermic. There is repulsion between the negative ion and the negative electron being added.

Question 10

Born harbour cycles

Answer 10

A technique for applying Hess’s law to enthalpy changes linked to ionic compounds forming

Question 11

What is Enthalpy change of solution

Answer 11

the enthalpy change when one mole of a solute dissolves in water.
lonic compounds dissolve in water. The ionic lattice breaks up (enthalpy of lattice dissociation) and the polar water molecules form bonds with the ions (enthalpy of hydration).

Question 12

What is enthalpy change of hydration

Answer 12

the enthalpy change when gaseous ions dissolve in water to form one mole of aqueous ions.

Question 13

When the ionic lattice dissolves, what are the two processes happening

Answer 13

1. lonic lattice breaks up into separate gaseous ions (opposite to lattice formation)
2. Each gaseous ion interacts with polar water molecules to form hydrated aqueous ions (enthalpy change of hydration)