# Question 7792a

Jun 21, 2017

I'll try and interpret the question correctly...

#### Explanation:

The first question is why nitrogen dioxide is ${\text{NO}}_{2}$ (I believe).

This comes from the nomenclature of nonmetal compounds; for binary covalent compounds such as nitrogen dioxide, they are named such that prefixes are attached to each element ( except if the first element has only $1$ of it in the compound, then no prefix is present).

"Nitrogen dioxide" thus means there is one nitrogen present and two oxygen atoms (prefix "di-" indicates $2$), the compound formula is ${\text{NO}}_{2}$.

The next question, I assume, is why the formula is not something else according to the chemical reaction

${\text{N"_2(g) + "O"_2(g) rarr "NO}}_{2} \left(g\right)$ (unbalanced)

Here's something worth knowing about chemistry and specifically chemical reactions: reactants can form products that have completely different characteristics than those of the reactants.

The fact that ${\text{N}}_{2}$ seems to lose its diatomic property is just the nature of the reaction; although ${\text{N"_2"O}}_{2}$ is a real compound, it is far less common to hear about it or work with it.

Basically, the chemical structure of ${\text{NO}}_{2}$ is thermodynamically more favorable than that of ${\text{N"_2"O}}_{2}$, and thus the reaction will, under certain conditions, yield ${\text{NO}}_{2}$ (you'll learn more about the thermodynamics of reactions later!)

As far as balancing goes, we have so far

• two nitrogens on the left, one on the right

• two oxygens on the left, two on the right

Therefore, nitrogen is the only unbalanced element. To fix this, we simply add a $\textcolor{red}{2}$ in front of ${\text{NO}}_{2}$:

${\text{N"_2(g) + "O"_2(g) rarr color(red)(2)"NO}}_{2} \left(g\right)$ (unbalanced)

Now you may notice that the oxygen quantities have become unbalanced, and there are $4$ on the right side and $2$ on the left. A quick fix is done by placing another color(blue)(2# in front of ${\text{O}}_{2}$:

${\text{N"_2(g) + color(blue)(2)"O"_2(g) rarr color(red)(2)"NO}}_{2} \left(g\right)$ (balanced)

And our equation is balanced!