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The energy required to break one mole of Cl−Cl bonds in Cl2 is 242 kJ mol^−1. The longest wavelength of light capable of breaking a single Cl−Cl bond is (c = 3 × 10⁸ ms^−1 and N_A = 6.02 × 10²³ mol^−1).
- 594 nm
- 640 nm
- 700 nm
- 494 nm
Correct answer: 494 nm
Solution
Energy per bond = 242000/6.02e23 = 4.02e-19 J. lambda = hc/E = (6.626e-34*3e8)/4.02e-19 = 4.95e-7 m ~ 494 nm.
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