OnlineCBT
Chemistry · THERMODYNAMICS
हिन्दीConsider the formation of ammonia: \( \frac{1}{2}\text{N}_2(g) + \frac{3}{2}\text{H}_2(g) \rightarrow \text{NH}_3(g) \); \( \Delta_r H^\ominus = -46.1\text{ kJ mol}^{-1} \). What is the enthalpy change accompanying the complete decomposition of \( 68\text{ g} \) of gaseous ammonia into its constituent elements at the same conditions?
Correct answer · Option 2
\( +184.4\text{ kJ} \)
Explanation
Moles of \( \text{NH}_3 = \frac{68}{17} = 4\text{ mol} \). Decomposition of 1 mol requires \( +46.1\text{ kJ} \). For 4 mol, \( \Delta H = 4 \times 46.1 = +184.4\text{ kJ} \).
