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Entropy

If C-C, C-H...

Question

If $C - C, C - H a n d C = O$ bond energies in acetaldehyde are $377, 421 a n d 720 k J m o l^{- 1}$ respectively, calculate the wavelength of radiation (in nm) required to bring about the photochemical decomposition of acetaldehyde.

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Solution

$E = h v = \frac{h c}{w a v e l e n g t h}$
$Δ E_{d e c o m p} = B E_{C - C}$
$= 377 k J m o l^{- 1} = 6.26 \times 10^{- 19} J / m o l e c u l e$
$∴ λ = \frac{6.626 \times 10^{- 34} \times 3 \times 10^{8}}{6.26 \times 10^{- 19}} = 317.5 n m$

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