UPSC Combined Geo-Scientist, Mains · 2024 · Mains Paper II

Q14(d). Quantum efficiency in the uranyl oxalate actinometer

5 marks
Topic: Photochemistry
Answered

Question

In the uranyl oxalate actinometer, 5.1875 × 10¹⁸ molecules were decomposed when exposed to a radiation of λ = 365.5 nm. During this time, the number of photons absorbed was 10.5875 × 10¹⁸. Calculate the quantum efficiency.

Answer in brief

Quantum efficiency ϕ = 0.490.

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Coversquantum yieldquantum efficiencyuranyl oxalate actinometerchemical actinometryphotosensitiser

All parts of Question 14

14(a) Non-degenerate and six-fold levels in a cubic box5 marks
14(b) Energies of the two levels for a 0.5 nm box5 marks
14(c) Wavelength of the (2,2,2)–(1,2,3) transition5 marks
14(d) Quantum efficiency in the uranyl oxalate actinometer5 marks