Question

Calculate the wavelength of light required to break the
bond between two chlorine atoms in a chlorine molecule.
The Cl - Cl bond energy is 243kJ mol-1
(h=6.6x10-34 Js; c = 3 x 108 ms -1,
Avogadro's number = 6.02 x1023 mol-1)
(a) 4.91 x 10-7m
(b) 4.11x 10-6 m
(c) 8.81 x 10-31 m
(d) 6.26 x 10-21 m
k
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Answer 1

Answer:

(a) 4.91 x 10-7m

Explanation:

​Hence, the energy required to dissociate a Cl-Cl bond in a chlorine (Cl2) molecule = 243000 J mol-1​ / 6.022 x 1023 mol-1 = 4.0 x 10-19 J

Since, E = hc/λ ; λ = hc/E

Hence,  

6.626 * 10^-34 * 3 * 10^8/4 * 10^-19

= 4.97 * 10^-7 m

 

= 497 nm