Question

If one mole of ammonia and one mole of hydrogen chloride are mixed in a closed container to form ammonium chloride gas, then

• A. $\Delta H > \Delta u$
• B. $\Delta H = \Delta u$
• C. $\Delta H < \Delta u$
• D. there is no relationship

Answer 1

Answer: (C)

$\underset{1 mol}{NH _{3}(g)}+ \underset{1 mol}{HCl (g)} \longrightarrow \underset{1 mol}{NH _{4} Cl (g)}$

$\Delta H=\Delta U+n_{g} R T$

$n_{g}=$ Number of moles of product

- number of moles of reactant

$=1-2=-1$

$ \Delta H=\Delta U-R T $

$\therefore \,\,\,\Delta H< \Delta U$