Question

A halogen like atom (HX) has a Pauling electronegativity of 2.75 and a bond dissociation energy of 180 kJ/mol. Using Pauling's electronegativity expression, predict the bond dissociation energy of HX

Answer 1

Xb - Xa = 0.208 * square root of (Da-b)

Xa = electro negativity of Hydrogen = 2.2

Xb = electro negativity of halogen = 2.75

Da-b = ionic resonance energy

2.75 - 2.2 = 0.208 * square root of (Da-b)

Da-b = 6.992 k cal/mol

Da-b = 6.992 * 4.184 kJ/mol

Da-b = 29.2545 kJ/mol

Da-b = Ea-b - (square root of (Ea-a * Eb-b))

Ea-b = bond dissociation energy of HX

Ea-a = bond dissociation energy of H2

Eb-b = bond dissociation energy of X2

29.2545 = Ea-b - (square root of (498.7 * 180)

Ea-b = 328.864 kJ/mol