AQA Chemistry A-level 3.1.8: Born-Haber Cycles Notes

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18 Questions

Why do gases generally have greater entropy compared to solids and liquids?

Gases have particles that are further apart

What does entropy measure in chemistry?


What happens to entropy as temperature increases?

Entropy increases

What change in entropy occurs when a substance melts or evaporates?

Sudden increase in entropy

What kind of entropy value do spontaneous reactions possess?

Positive entropy value

How does Gibbs Free-Energy help determine entropy without measuring effects on surroundings?

By allowing determination of ∆S values directly

What is lattice dissociation enthalpy?

The energy required to break apart an ionic lattice into its constituent ions in a gaseous state

What is the definition of atomisation enthalpy?

The energy required for the formation of a mole of gaseous atoms

What does the enthalpy of electron affinity measure?

Enthalpy change when adding electrons to atoms

What type of substances are lattice enthalpies used for?

Ionic substances

How are Born-Haber cycles related to Hess's Law?

They represent reactions as vectors

Which term describes the energy required to form an ionic lattice from its constituent ions?

Lattice formation enthalpy

What happens to the sign of the enthalpy change if the cycle counters the direction of the arrow?

It becomes negative

How is enthalpy of solution defined?

The enthalpy change when an ionic solid is dissolved in water to infinite dilution

What is enthalpy of hydration defined as?

The enthalpy change when gaseous ions are dissolved in water

Why is enthalpy of hydration nearly always negative?

Because water has a positive region that attracts negative ions

In the perfect ionic model, what assumption is made about the ions?

They are perfectly spherical and show no covalent character

How are enthalpies of solution and hydration combined to form an energy cycle?

Through a similar idea to Hess's Law

Explore detailed notes on Born-Haber cycles in AQA Chemistry A-level 3.1.8, which are essential for determining enthalpy changes in ionic substances. Learn how to use Born-Haber cycles similar to Hess's Law cycles to calculate lattice enthalpies.

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