A) -14.5 kcal
B) - 15.4 kcal
C) + 14.5 kcal
D) + 15.4 kcal
Correct Answer: A
Solution :
[a] : The formation of \[C{{H}_{3}}OC{{H}_{3}}\]may be represented as \[2{{C}_{(s)}}+3{{H}_{2(g)}}+\frac{1}{2}{{O}_{2(g)}}\xrightarrow[{}]{{}}\] \[C{{H}_{3}}-O-C{{H}_{3(g)}};\Delta H=?\] It involves vaporisation of 2 gram atoms of solid carbon and breaking of 3 moles of H - H bonds and \[\frac{1}{2}\]mole of \[O=O\] bond resulting in the formation of \[6\text{ }C-H\] bonds and \[2\text{ }C-O\] bonds. Thus, the heat of formation of \[C{{H}_{3}}-O-C{{H}_{3}}\] is given by \[\Delta H=(2\times 125+3\times 103+\frac{1}{2}\times 177)\] \[-(6\times 87+2\times 70)\] \[=-14.5\,\text{kcal}\]You need to login to perform this action.
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