# Given N_2(g) +3H_2(g) rarr 2NH_3(g)+92*kJ...what energy is associated with the formation of A. "4 moles of ammonia"; and B. "4 g ammonia is produced"?

Oct 11, 2016

${N}_{2} \left(g\right) + 3 {H}_{2} \left(g\right) \rightarrow 2 N {H}_{3} \left(g\right) + \Delta$

$A .$ $=$ -368*kJ; $B .$ $=$ $- 10.8 \cdot k J$

#### Explanation:

The given thermodynamic paramters are always quoted per mol of reaction as written. Thus if the one mole of dinitrogen reacts, $- 92 \cdot k J \cdot m o {l}^{-} 1$ (of given reaction) are evolved. If 4 moles, then $- 368 \cdot k J$

If $4 \cdot g$ ammonia are produced, this is a molar quantity of $\frac{4.00 \cdot g}{17.03 \cdot g \cdot m o {l}^{-} 1}$ $=$ $0.235 \cdot m o l$.

Given that $- 46 \cdot k J$ are produced per mole of ammonia, this gives a quantity of $- 46 \cdot k J \cdot m o {l}^{-} 1 \times 0.235 \cdot m o l$ $=$ $- 10.8 \cdot k J$.

Why is this an important reaction?