Exam Level Born Haber Cycles

LOsTo understand the style of question asked for this unitTo improve the speed at which these questions are completed.

Enthalpies of Solution

LOsTo be able to calculate the enthalpy of solution

Define

1) The standard lattice enthalpy

2) The standard enthalpy of hydration

3) The standard enthalpy of solution

Dissolving

Similar looking diagram

OR Hess’s Law Triangle

Worked example

Ionic charge and radius

Ions with a higher charge have a higher enthalpy of hydration (more exothermic)

Ions with a smaller radius have a higher enthalpy of hydration (more exothermic)

Exam Questions

Entropy

Entropy is a measure of the number of different ways particles can be arranged.

It is a bit like how disordered or chaotic the system is.

Substances are more energetically stable as the system become more disordered.

Simple examples

Entropy tells us if a reaction will happen

ΔStotal = total entropy.

Spontaneous Reactions

For a reaction to happen spontaneously, the ΔG most be zero or negative.