Question

If $ \Delta E $ is the heat of reaction for
$ \ce{C2H5OH(l) + 3O2_{(g)} -> 2CO2_{(g)} +3H2O(l)} $ at constant volume, the $ \Delta H $ (heat of reaction at constant pressure), at constant temperature is

• A. $ \Delta H=\Delta E+RT $
• B. $ \Delta H=\Delta E-RT $
• C. $ \Delta H=\Delta E-2RT $
• D. $ \Delta H=\Delta E+2RT $

Answer 1

Answer: (B)

We know that,

$\Delta H=\Delta E+\Delta n R T$

where,

$\Delta n=$ number of moles of gaseous products

- number of moles of gaseous reactants

$=2-3=-1 $

So, $\Delta H=\Delta E-R T$