Atomic Structure - Result Question 103
####79. Iodine molecule dissociates into atoms after absorbing light to $4500 \AA$. If one quantum of radiation is absorbed by each molecule, calculate the kinetic energy of iodine atoms. (Bond energy of $I _2=240 kJ mol^{-1}$ )
(1995, 2M)
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Answer:
Correct Answer: 79. $(660 nm)$
Solution:
- After breaking of the bond of $I _2$ molecule, the remaining energy would be distributed uniformly to iodine atoms as their kinetic energy, i.e.
$E($ energy of photon $)=$ Bond energy $+2 \times$ kinetic energy
$$ \begin{array}{rlrl} \Rightarrow & & \frac{6.625 \times 10^{-34} \times 3 \times 10^{8}}{4500 \times 10^{-10}} & =\frac{240 \times 10^{3}}{6.023 \times 10^{23}}+2 \times E _k \ \Rightarrow & E _k & =2.16 \times 10^{20} J / \text { atom } \end{array} $$
