Question

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

• A. $H _{2}(g)+ Br _{2}(g) \longrightarrow 2 HBr (g)$
• B. $C ( s )+2 H _{2} O (g) \longrightarrow 2 H _{2}(g)+ CO _{2}(g)$
• C. $PCl _{5}(g) \longrightarrow PCl _{3}(g)+ Cl _{2}(g)$
• D. $2 CO (g)+ O _{2}(g) \longrightarrow 2 CO _{2}(g)$

Answer 1

Answer: (A)

$\Delta H=\Delta E+p \Delta V$
$\Delta H=\Delta E+\Delta n R T $
open container, therefore $\Delta H=\Delta E$
So, for the reaction (a). $\Delta n=2-2=0$
Hence, for the reaction, $\Delta H=\Delta E$.