Explanations:
• We will follow Hess's Law of Constant Heat Summation:
(that states that if a reaction occurs in more than one route, then the the total enthalpy change for the reaction is the sum of all changes.)
For reaction :
[tex]\begin{gathered} B\Rightarrow C\text{ }\Delta H\text{ = 415.3 kJ }\ldots\text{.}\mathrm{}(\text{ reaction 1)} \\ A+B\text{ }\Rightarrow\text{ D }\Delta H\text{ = -95.7kJ}\ldots.(\text{ reaction 2 ) } \\ 6A\text{ }\Rightarrow6E\text{ }\Delta H\text{ = 207.9kJ }\ldots\ldots(\text{reaction 3 ) } \end{gathered}[/tex]this can be expressed as :
[tex]\begin{gathered} \Delta H_{total\text{ }}=\text{ }\frac{207.9}{6\text{ }}+(-95.7\text{ ) - 415}.3\text{ } \\ \text{ = 34.65 -95.7 -415.3} \\ \text{ =-476.35kJ} \end{gathered}[/tex]