A) -17 kcal
B) -111 kcal
C) -170 kcal
D) -85 kcal
Correct Answer: A
Solution :
For reaction, \[C(s)+2{{H}_{2}}(g)\xrightarrow[{}]{{}}C{{H}_{4}}(g),\,\Delta {{H}^{o}}=\,?\] \[\Delta {{H}^{o}}=-[(\Delta {{H}^{o}}\] of combustion of \[C+2\times \Delta H\] of combustion of \[{{H}_{2}})]\] \[C+{{O}_{2}}\xrightarrow{{}}C{{O}_{2}};\,\,\,\Delta H=-94\,\,kcal\] ...(i) \[2{{H}_{2}}+{{O}_{2}}\to 2{{H}_{2}}O;\Delta H=-68\times 2\,kcal\] ?(ii) \[C{{H}_{4}}+2{{O}_{2}}\to C{{O}_{2}}+2{{H}_{2}}O;\,\,\Delta H=-213\,kcal\] ?(iii) \[=-[(-213)-(-94+2\times -68)]\,\text{kcal/mol}\] \[=-[-213+230]=-17\,\,\text{kcal/mol}\]You need to login to perform this action.
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