Born Harbour Cycles And Solution Cycles

Question 1

What is lattice enthalpy?

Answer 1

This is the enthalpy change when 1 mole of solid ionic lattice is formed from its gaseous ions

Question 2

What factors affect lattice enthalpy?

Answer 2

1. Ionic charge
2. Ionic radius

Question 3

How does ionic charge affect lattice enthalpy?

Answer 3

-The higher the charges in the ions, the stronger the electrostatic attractions

-so more energy is released when an ionic lattice is formed

Question 4

How does ionic radius affect lattice enthalpy?

Answer 4

-The smaller the ionic radii of the ions involved, the higher the charge density of the ion

• this means more electrostatic attraction between the ions is greater so the lattice enthalpy is more exothermic

Question 5

What is enthalpy of formation?

Answer 5

The enthalpy change when 1 mole of a compound is formed from its elements

Question 6

What is the enthalpy of atomisation?

Answer 6

The enthalpy change when 1 mole of gaseous atoms is formed from an element

Question 7

What is the fist ionisation energy?

Answer 7

The energy needed to change 1 mole of gaseous atoms into 1 mole of gaseous 1+ ions

Question 8

What is the second ionisation energy?

Answer 8

The energy needed to change 1 mole of gaseous 1+ ions into 1 mole of gaseous 2+ ions

Question 9

What is electron affinity?

Answer 9

This is the energy needed to change 1 mole of gaseous atoms into 1 mole of gaseous 1- ions

Question 10

What is second electron affinity?

Answer 10

This is the energy needed to change 1 mole gaseous 1- ions into 1 mole of gaseous 2- ions

Question 11

What is the enthalpy change of hydration?

Answer 11

Is the enthalpy change when 1 mole of gaseous ions is dissolved in water

Question 12

What is the enthalpy change of solution?

Answer 12

This is the enthalpy change when 1 mole of solute is dissolved in a solvent such as water

Question 13

Describe the order of born-haber cycles?

Answer 13

1) solid ionic substance

2) enthalpy of formation= elements in solid state- exothermic

3) atomise metal-endothermic

4) atomise non-metal-endothermic

5)ionise the metal-endothermic

6) electron affinity of non metal=ions in gaseous state- exothermic

7) enthalpy of lattice-exothermic

Question 14

Is second electron affinity endothermic or exothermic?

Answer 14

Endothermic

Question 15

What are steps of a solution cycle?

Answer 15

1. Start of with gaseous ions at the top
2. Then hydrate the metal- exo
3. Hydrate the non metal- exo
4. On the bottom you’d have the ions in aqueous form
5. Then have an arrow coming down for enthalpy of solution- exo
6. Lattice enthalpy- ionic solid- exo

Question 16

What factors affect enthalpy of hydration?

Answer 16

1. Ionic charge
2. Ionic radius

Question 17

How does ionic charge affect enthalpy of hydration?

Answer 17

Ions with a higher charge are better at attracting water molecules than those with lower charges. More energy is released when the bonds are made making enthalpy of hydration more exothermic

Question 18

How does ionic radius affect enthalpy of hydration?

Answer 18

Smaller ions have a greater enthalpy if hydration this is because smaller ions have a higher charge density than bigger ions, so they attract the water molecules better and have a more exothermic enthalpy of hydration.