Question

The heat of atomisation of methane and ethene are 360 kJ/mol and 620 kJ/mol, respectively. The longest wavelenth of light capable of breaking the C-C bond is (Avogadro number `=6.02xx10^(23),h=6.62xx10^(-34)` Js)
A. `2.48xx10^(3)nm`
B. `1.49xx10^(3)nm`
C. `2.49xx10^(5)nm`
D. `2.48xx10^(4)nm`

Answer 1

Correct Answer - D
`4BE(C_H)` bond =360kJ/mol
`BE(C-H)` bond =90kJ/mol
In `C_(2)H_(6)implies BE_((C-C))+6BE_((C-H))=620kJ//mol`
`BE_((C-C))` bond`=620-6xx90=80kJ//mol`
`lamda` for rupture of `C-C` bond `=(6.262xx3xx10^(8))/(80xx10^(3))`
`=2.48475xx10^(4)nm`