Q2(a)(i). Dipole moments of CF₄ and CH₂F₂
Explain the following: The dipole moment of CF₄ is less than that of CH₂F₂.
Answer in brief
CF₄ is a regular tetrahedron: its four equal C–F bond dipoles cancel by symmetry, μ=0. In CH₂F₂ the two C–F dipoles add along the bisector and the C–H bonds cannot cancel them, so μ≠0 (about 1.97 D).
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All parts of Question 2
- 2(a)(i) Dipole moments of CF₄ and CH₂F₂5 marks
- 2(a)(ii) CO₂ linear, SO₂ bent5 marks
- 2(a)(iii) Bond order of NO and NO⁺; magnetic behaviour10 marks
- 2(b) Partition function as a product of two partition functions10 marks
- 2(c) Adsorption theory of catalysis: steps and example10 marks