Radium is a Group 2 element. The predicted lattice energy, ∆H°latt, of radium sulfide, RaS, is –2612kJ mol⁻¹. Some data relating to radium and sulfur are listed. Select relevant data from this list for use in your answers to parts (b) to (e). process value/kJ mol⁻¹ enthalpy change for Ra(s) → Ra²⁺(g) + 2e⁻ +1619 first ionisation energy of sulfur +1000 second ionisation energy of sulfur +2260 first electron affinity of sulfur -200 second electron affinity of sulfur +532 enthalpy change for S(s) + 2e⁻ → S²⁻(g) +555 lattice energy of RaS(s) -2612

1. (a)Define ∆H°latt.[2]
2. (b)Write an equation for the process corresponding to the second electron affinity of sulfur. Include state symbols.[1]
3. (c)Sulfur exists as S₈ molecules in the solid state. Use the data in this question to calculate the enthalpy change for the reaction S₈(s) → 8S(g). enthalpy change =[3]
4. (d)Calculate the standard enthalpy change of formation, ∆H°f, of radium sulfide. standard enthalpy change, ∆H°f =[2]
5. (e)(i)State the two major factors that affect the numerical magnitude of a lattice energy.[2]
6. (e)(ii)For each factor you have identified in (e)(i), state whether it tends to make the lattice energy of radium sulfide more or less exothermic than that of sodium chloride. Explain your answer.[2]
7. (e)(iii)The lattice energies of sodium chloride, NaCl, and radium sulfide, RaS, are –771 kJ mol⁻¹ and -2612kJ mol⁻¹, respectively. Identify the dominant factor in determining the relative numerical magnitudes of the lattice energies of radium sulfide and sodium chloride. Explain your answer.[1]