During a semiconductor-etching process, engineers must remove residual halogen gases by dissolving them in a chilled bath of liquid N,N-dimethylformamide (DMF), which has a dipole moment of 3.86 D. Two candidate waste gases are molecular fluorine (F₂) and molecular chlorine (Cl₂).
Relevant molecular data at 5 °C:
• F₂: polarizability α = 1.43 ų, molar mass = 38 g mol⁻¹
• Cl₂: α = 5.40 ų, molar mass = 71 g mol⁻¹
Assume the bath is vigorously stirred so that gas-phase mass-transfer limitations are negligible.
(a) Predict which gas will exhibit the stronger overall attractive interaction with liquid DMF. Provide a clear justification based on the data given.
(b) Using an appropriate proportional argument, estimate the ratio of the expected dipole-induced dipole interaction energies (DMF–Cl₂ to DMF–F₂). Show all reasoning steps.
(c) Despite the interaction-energy difference you estimated in part (b), the dissolution rate of F₂ into DMF is observed to be comparable to that of Cl₂. Propose one kinetic or thermodynamic factor—unrelated to dipole-induced dipole interactions—that could account for the similar rates, and explain your proposal.