1 What is the equation for the first electron affinity of sulfur? S(s) + e S (g) S(g) + e S (g) S(s) S + (g) + e S(g) S + (g) + e 2 The diagram shows a orn-haber cycle for calcium chloride. It is not drawn to scale. ll units are in kj mol _ 1. a 2+ (g) 2l _ (g) Q = +1735 R = ( 346 2) = 692 P = 2258 a(g) + 2l(g) +178 S = (+121 2) = +242 al 2 (s) X =? a(s) + l 2 (g) (a) Which enthalpy change is correctly labelled on the diagram? Enthalpy change for the formation of calcium chloride (P). (1) First ionization energy of calcium (Q). Electron affinity of chlorine (R). Twice the enthalpy change of atomization of chlorine (S). (b) What is the value of X, in kj mol _ 1? +795 (1) 795 +3721 3721 = 2 marks) PhysicsndMathsTutor.com
3 Which of the following data is not needed to calculate the lattice energy of sodium chloride when using a orn-haber cycle? Enthalpy change of formation of sodium chloride. Enthalpy change of atomization of sodium. First ionization energy of chlorine. Electron affinity of chlorine. 4 The lattice energy of magnesium oxide is more negative than the lattice energy of magnesium fluoride because oxide ions are larger than fluoride ions. oxide ions are larger than magnesium ions. oxide ions are more highly charged than fluoride ions. there is only one oxide ion but two fluoride ions per magnesium ion. PhysicsndMathsTutor.com
5 Which of the following quantities, used in the calculation of the lattice energy of lithium oxide, Li 2 O, has a negative value? The enthalpy change of atomization of lithium. The first ionization energy of lithium. The first electron affinity of oxygen. The second electron affinity of oxygen. 6 Which of the diagrams below best represents the shapes of the electron contours in sodium fluoride? + + + + PhysicsndMathsTutor.com
7 Which of the equations below represents the first electron affinity for oxygen? O 2 (g) + 2e 2O (g) O 2 (g) 2e 2O (g) ½O 2 (g) + e O (g) O(g) + e O (g) 8 Which of the following oxides would be expected to have the most exothermic lattice energy? Na 2 O MgO ao K 2 O 9 In the orn-haber cycle for potassium iodide, which of the following steps is exothermic? K(s) K(g) K(g) K + (g) + e ½I 2 (s) I(g) I(g) + e I (g) PhysicsndMathsTutor.com
10 Magnesium chloride, Mgl 2, has two lattice energy values quoted in the data booklet. 1 ; 1. Why are the two values different? The cation polarizes the anion leading to some covalent bonding. The anion polarizes the cation leading to some covalent bonding. Magnesium chloride is a covalent substance. The results from the orn-haber cycle are too inaccurate to be reliable. 11 Which of the following represents the process occurring when the enthalpy change of atomization of bromine is measured? ½r 2 (l) r(g) ½r 2 (g) r(g) r 2 (l) r + (g) + r (g) r 2 (g) r + (g) + r (g) 12 The standard enthalpy changes of formation of some sulfur species are: Species H f / kj mol 1 S 8 (s) 0 S 8 (g) +103 S(g) +279 The enthalpy of atomization of sulfur is (in kj mol 1 ) 103 279 279 (103 8) + 279 PhysicsndMathsTutor.com
13 Which of these equations represents the electron affinity of chlorine? l 2 (g) + 2e 2l (g) l 2 (g) 2e 2l (g) ½l 2 (g) + e l (g) l(g) + e l (g) 14 Which of these ions has the greatest ability to polarize an anion? a 2+ a 2+ s + K + PhysicsndMathsTutor.com
15 The following cycle represents the enthalpy changes w, x, y and z, occurring when an ionic solute, X 2 (s), dissolves in water. w 2+ (g) + 2X (g) X 2 (s) z x + y 2+ (aq) + 2X (aq) Which of the changes is the lattice energy of X 2 (s)? ½ w w z z x y 16 H for the process I 2 (s) I 2 (g) I 2 (s) 2I(g) I 2 (g) 2I(g) ½I 2 (s) I(g) PhysicsndMathsTutor.com
17 The ionic radii in nm of some ions are given below. Li + 0.074 F 0.133 a 2+ 0.100 l 0.180 O 2 0.140 S 2 0.185 (a) Which of the following compounds has the most exothermic lattice energy? They all have the same crystal structure. (1) LiF Lil ao as (b) Which of the following compounds will show the greatest difference between the experimental (orn-haber) lattice energy and that calculated from a purely ionic model? (1) LiF Li 2 O ao as 2 marks) PhysicsndMathsTutor.com
18 The equation for the enthalpy of hydration for a magnesium ion is Mg 2+ (s) + aq Mg 2+ (aq) Mg 2+ (g) + aq Mg 2+ (aq) Mg 2+ (aq) Mg 2+ (g) + aq Mg 2+ (aq) Mg 2+ (s) + aq 19 Which reaction has an enthalpy change equal to the enthalpy of hydration of the sodium ion? Na + (g) + excess H 2 O(l) Na + (aq) Na + (g) + 1 mol of H 2 O(l) Na + (aq) Na + (s) + excess H 2 O(l) Na + (aq) Na + (s) + 1 mol of H 2 O(l) Na + (aq) PhysicsndMathsTutor.com