Question

If $\Delta H$ is the change in enthalpy and $\Delta E$ the change in internal energy for a gaseous reaction then

• A. $\Delta H$ is always greater than $\Delta E$
• B. $\Delta H < \Delta E$ only if the number of moles of the products is greater than the number of the reactants
• C. $\Delta H$ is always less than $\Delta E$
• D. $\Delta H < \Delta E$ only if the number of moles of the products is less than the number of moles of the reactants

Answer 1

Answer: (D)

The change in enthalpy and the change in internal energy for a gaseous reaction is given by
$\Delta H=\Delta E+\Delta n_{g}RT$
If $\Delta n=-ve$ than $\Delta H < \Delta E$ .