Question

If enthalpy of an overall reaction $X \rightarrow Y$along one route is $\Delta_{r}H$ and $\Delta_{r}H_{1}\Delta_{r}H_{2}\Delta_{r}H_{3}....$ representing enthalpies of reactions leading to same product Y then $\Delta_{r}H$ is

• A. $\Delta_{r}H = \Delta_{r}H_{1} + \Delta_{r}H_{2} + \Delta_{r}H_{3}....$
• B. $\Delta_{r}H = \Delta_{r}H_{1} \times \Delta_{r}H_{2} \times \Delta_{r}H_{3}....$
• C. $\Delta_{r}H = \Delta_{r}H_{1} + \Delta_{r}H_{2} - \Delta_{r}H_{3}....$
• D. $\Delta_{r}H = \frac{\Delta_{r}H \times \Delta_{r}H_{2} \times \Delta_{r}H_{3}}{2}....$

Answer 1

Answer: (A)

$\Delta_{r}H = \Delta_{r}H_{1} + \Delta_{r}H_{2} + \Delta_{r}H_{3}....$

Answer 2

: According to Hess’s law,

$\Delta_{r}H = \Delta_{r}H_{1} + \Delta_{r}H_{2} + \Delta_{r}H_{3}...$

Where $H_{1},H_{2},H_{3},$ etc. are enthalpies of various steps.