Answer to Question #75225 in Inorganic Chemistry for Arun Rawat

Question

3. a) Explain the reason for the variation of the first ionization energies of the third period  elements. (4) b) Calculate the lattice energy (in Units kJ mol1 ) for ZnO crystal using Eq. 3.4 based on  electrostatic model and using a Born-Haber cycle. Compare the two answers and comment  on any difference. Useful data: Medelung constant (A) = 1.6411 Born Constant (n) = 8 Internuclear distance (a) = 199 pm Zn(s) + ½ O2(g)  ZnO(s) Hf =  350.5 kJ mol1 Zn(s)  Zn(g) HS = 130.4 kJ mol1 Zn(g)  Zn+ (g) I(Zn) = 906.3 kJ mol1 Zn+ (s)  Zn2+(g) I(Zn+ ) = 1733 kJ mol1 ½ O2(g)  O(g) ½Hd = 248.5 kJ mol1 O(g)  O  (g) EA(O) = 141 kJ mol1 O - (g)  O 2 (g) EA(O ) = 780 kJ mol1