# For which reaction is the enthalpy equal to DeltaH_"f"^@ of NO(g)?

## For which reaction is the enthalpy equal to $\Delta {H}_{\text{f}}^{\circ}$ of $N O \left(g\right)$? $A .$ $N O \left(g\right) \rightarrow \frac{1}{2} {N}_{2} \left(g\right) + \frac{1}{2} {O}_{2} \left(g\right)$ $B .$ $N \left(g\right) + {O}_{2} \left(g\right) \rightarrow 2 N O \left(g\right)$ $C .$ $\frac{1}{2} N \left(g\right) + \frac{1}{2} {O}_{2} \left(g\right) \rightarrow N O \left(g\right)$ $D .$ ${N}_{2} O \left(g\right) \rightarrow {N}_{2} \left(g\right) + \frac{1}{2} {O}_{2} \left(g\right)$

Aug 12, 2017

A very poor question....even by the standards of most multiple choice questions.....I would plump for $C$.......

#### Explanation:

The choice is between $C$ and $D$. Dinitrogen gas is moderately reactive; much less reactive than dioxygen. Nevertheless, dinitrogen can be oxidized.....

$\frac{1}{2} {N}_{2} \left(g\right) + \frac{1}{2} {O}_{2} \left(g\right) \stackrel{h \nu}{\rightarrow} N O$

And it can also be reduced.......

$\frac{1}{2} {N}_{2} \left(g\right) + 3 L i \left(s\right) \rightarrow L {i}_{3} N$

I would be interested in the answer given by your lecturer. This one would stump most professors, and it should not be asked of an undergraduate.