A) \[210\text{ }kcal\text{ }mo{{l}^{-1}}\]
B) \[~80\text{ }kcal\text{ }mo{{l}^{-1}}\]
C) \[130\text{ }kcal\text{ }mo{{l}^{-1}}\]
D) \[180\text{ }kcal\text{ }mo{{l}^{-1}}\]
Correct Answer: B
Solution :
[b] Atomisation of methane \[C{{H}_{4}}\left( g \right)\xrightarrow{{}}C\left( g \right)+4H\left( g \right);\] \[\Delta H=360\text{ }kcal\] \[\therefore \text{ }C-H\] bond energy \[=\frac{360}{4}\] \[=90\text{ }kcal\text{ }mo{{l}^{-1}}\] \[{{C}_{2}}{{H}_{6}}(g)\xrightarrow{{}}2C(g)+6H(g);\] \[\Delta H=620\text{ }kcal\] or \[{{H}_{C-C}}+6{{H}_{C-H}}=620\] \[\therefore {{H}_{C-C}}=620-6{{H}_{C-H}}\] \[=620-6\times 90=80\text{ }kcal\text{ }mo{{l}^{-1}}\]You need to login to perform this action.
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