3.1.8.1 Born-Haber cycles (A-level only)

Which equation represents the process that occurs when the standard enthalpy of atomisation of iodine is measured?

• 0.5I₂(s) → I(g)

• I₂(s) → 2I(g)

• 0.5I₂(g) → I(g)

• I₂(g) → 2I(g)

Lattice enthalpy values can be obtained from Born–Haber cycles and by calculations based on a perfect ionic model.

Which compound shows the greatest percentage difference between these two values?

• CsF

• CsI

• LiF

• LiI

Which one of the following statements is not correct?

• The first ionisation energy of iron is greater than its second ionisation energy.

• The magnitude of the lattice enthalpy of magnesium oxide is greater than that of barium oxide.

• The oxidation state of iron in [Fe(CN)₆]³⁻ is greater than the oxidation state of copper in [CuCl₂]⁻

• The boiling point of C₃H₈ is lower than that of CH₃CH₂OH

Which one of the following has the most covalent character?

• MgF₂

• MgBr₂

• AlF₃

• AlBr₃