# Question #acdf3

Dec 10, 2014

The balanced equation is:

$4 N {H}_{3 \left(g\right)} + 7 {O}_{2 \left(g\right)} \rightarrow 4 N {O}_{2 \left(g\right)} + 6 {H}_{2} {O}_{\left(g\right)}$

Yes, oxygen must have a subscript of two beacause it forms diatomic molecules. There are seven elements (all gases) that do so:

Oxygen - ${O}_{2}$, Hydrogen - ${H}_{2}$, Nitrogen - ${N}_{2}$, Fluorine - ${F}_{2}$, Iodine - ${I}_{2}$, Chlorine - $C {l}_{2}$, and Bromine - $B {r}_{2}$

These elements will always have a subscript of 2 when alone in a reaction.