2.4 Born Haber Cycle

Identify the enthalpy change represented by letter g.

• Enthalpy of formation

• Enthalpy lattice of formation

• Electron affinity of bromine

• Enthalpy of atomisation of zinc

First electron affinity of an element is usually ________ and second electron affinity is ____________.

• exothermic, endothermic.

• exothermic, exothermic.

• endothermic, endothermic.

• endothermic, exothermic.

Given the Born-Haber cycle below, which of the following enthalpy change is not represented by steps a-g

• Enthalpy of formation

• Enthalpy of atomization of calcium

• 1^st electron affinity of bromine

• 2^nd electron affinity of bromine

Mg (g) --> Mg+ (g) + e-

• Ionisation

• Combustion

• Formation

• Hydration

Which of the equation below refers to the standard enthalpy of formation, ΔH_f^o?

• Na(g) ---> Na⁺(g) + e^- ΔH = -364 kJmol^-1

• C₂H₅OH (l) + 3O₂ (g) ---> 2 CO₂(g) + 3H₂O (l) ΔH = - 1286 kJmol^-1

• 2C (s) + 2H₂ (g) ---> C₂H₄ (g) ΔH = - 52.3 kJmol^-1

• Na⁺(g) ---> Na⁺(aq) ΔH = - 364 kJmol^-1

What is the definition of lattice enthalpy?

• Heat released when one mole of solid ionic compound is formed from its gaseous ions.

• Heat released when an ionic lattice is formed from one mole of its gaseous ions.

• Heat released when one mole of an ionic lattice is formed from ions in their standard states.

• Heat released when an ionic lattice is formed from one mole of gaseous atoms.

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

What enthalpy change does the number 4 represent?

• Formation

• 1^st ionisation energy of Na

• 1^st electron affinity of Na

• Atomisation of Na

Enthalpy change is represented by step y ?

• Enthalpy of formation calcium bromide

• Enthalpy of atomisation of calcium

• 1^st electron affinity of bromine

• Enthalpy of atomisation of bromine

Calculate value x.

• -1970 kJ

• -266 kJ

• +266 kJ

• +1970 kJ