Question #7792a

1 Answer
Jun 21, 2017

Answer:

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

Explanation:

The first question is why nitrogen dioxide is #"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 #"NO"_2#.

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

#"N"_2(g) + "O"_2(g) rarr "NO"_2(g)# (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 #"N"_2# seems to lose its diatomic property is just the nature of the reaction; although #"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 #"NO"_2# is thermodynamically more favorable than that of #"N"_2"O"_2#, and thus the reaction will, under certain conditions, yield #"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 #color(red)(2)# in front of #"NO"_2#:

#"N"_2(g) + "O"_2(g) rarr color(red)(2)"NO"_2(g)# (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 #"O"_2#:

#"N"_2(g) + color(blue)(2)"O"_2(g) rarr color(red)(2)"NO"_2(g)# (balanced)

And our equation is balanced!