A2 CHEMISTRY

Suggest why the second and third electron affinities are always endothermic.

the first electron affinity of iodine

• I(g) + e− → I⁻ (g)

• I(g) + e− → I(g)

• I₂(g) + e− → I⁻ (g)

• I(g) + e− → I²⁻ (g)

For each pair of compounds, suggest which will have the most exothermic lattice energy, KCl and BaO

For each pair of compounds, suggest which will have the most exothermic lattice energy, MgI₂ and SrI₂

Write equations describing the lattice energy of magnesium oxide.

• K⁺ (g) + Br⁻ (g) → KBr(s)

• Mg²⁺ (g) + O²⁻ (g) → MgO(s)

• 2Mg⁺ (g) + O²⁻ (g) → Mg₂O(s)

• 2Na⁺ (g) + S²⁻ (g) → Na₂S(s)

Which one of the following ions will be the best polariser of the large nitrate ion?

• Cs+

• Li+

• Na+

• K +

Name the changes associated with the equations below

• the enthalpy change of hydration of Br−

• the lattice enthalpy

• the enthalpy change of hydration K+

• the enthalpy change of solution

Calculate the enthalpy of hydration of magnesium ions given that:

ΔH⦵latt [MgCl2 ] = −2592 kJ mol−1

ΔH⦵sol [MgCl2 ] = −55 kJ mol−1

ΔH⦵hyd [Cl−] = −364 kJ mol−1

Why does an ionic compound have to be molten to undergo electrolysis?

Calculate the mass of lead deposited at the cathode during electrolysis when a current of 1.50 A

flows through molten lead(II) bromide for 20.0 min.(Ar value: [Pb] = 207; F = 96 500 C mol⁻¹ )

• 1.93
• 2.01

• 1.05

• 1.68