Indian Forest Service (Mains), Chemistry optional · 2025 · Paper II
Q8(b)(i). Isotope exchange and zero-point energy
Question
Calculate the energy change for HCl + D₂ → DCl + HD using vibrational wavenumbers 2885, 2990, 1990 and 3627 cm⁻¹ respectively and the stated h and c.
Answer in brief
The zero-point contribution is ΔE = −2.564 × 10⁻²¹ J per reaction event, or approximately −1.544 kJ mol⁻¹.
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Coverszero-point energyisotope exchange reactionvibrational wavenumberHCl and D₂harmonic oscillator
All parts of Question 8
- 8(a)(i) CO rotational constant and bond length10 marks
- 8(a)(ii) Isotopic change in rotational constant5 marks
- 8(b)(i) Isotope exchange and zero-point energy10 marks
- 8(b)(ii) Hot-band population in iodine10 marks
- 8(c) Metalation of thiophene5 marks