Assume each reaction is carried out in an open container. For which reaction will $\Delta H=\Delta E ?$

Assume each reaction is carried out in an open container. For which reaction will $\Delta H=\Delta E ?$
  1. $2 \mathrm{CO}_{(\mathrm{g})}+\mathrm{O}_{2(\mathrm{~g})} \rightarrow 2 \mathrm{CO}_{2(\mathrm{~g})}$
  2. $\mathrm{H}_{2(g)}+\mathrm{Br}_{2(g)} \rightarrow 2 \mathrm{HBr}_{(\mathrm{g})}$
  3. $\mathrm{C}_{(\mathrm{s})}+2 \mathrm{H}_2 \mathrm{O}_{(\mathrm{g})} \rightarrow 2 \mathrm{H}_{2(g)}+\mathrm{CO}_{2(g)}$
  4. $\mathrm{PCl}_{5(g)} \rightarrow \mathrm{PCl}_{3(g)}+\mathrm{Cl}_{2(g)}$

Solution

$\mathrm{For}_2(g)+\mathrm{Br}_2(g) \rightarrow 2 \mathrm{HBr}(g)$ $\begin{array}{ll} \because & \Delta n_g=0 \\ \therefore & \Delta \mathrm{H}=\Delta \mathrm{E}+\Delta n_g \mathrm{RT} \\ \Rightarrow & \Delta \mathrm{H}=\Delta \mathrm{E} \end{array}$

Asked in: NEET 2006

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