1. Tardigrade
  2. Question
  3. Chemistry
  4. Consider the reaction N2 +3H2 -> 2NH3 carried out at constant temperature and pressure. If ΔH and ΔU are the enthalpy and internal energy changes for the reaction, which of the following expressions is true ?

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Q. Consider the reaction
$ \ce{N2 +3H2 -> 2NH3} $
carried out at constant temperature and pressure. If $ ΔH $ and $ ΔU $ are the enthalpy and internal energy changes for the reaction, which of the following expressions is true ?

UPSEEUPSEE 2007

Solution:

$\Delta H=\Delta U+\Delta n_{g}\,RT$
$ΔH =$ enthalpy change (at constant pressure)
$ΔU =$ internal energy change (at constant volume) (given reaction is exothermic)
$Δn_g =$ mole of (gaseous products $-$ gaseous reactants)
$=-ve$
Thus, $ΔH < ΔU$