What is the oxidation number of nitrogen in N_2O_5?

Oct 22, 2016

$+ 5$

Explanation:

Two things come in handy here

• for a neutral compound, the sum of the oxidation numbers of all constituent atoms must be equal to zero
• the oxidation number of oxygen is usually equal to $- 2$

This means that if you take ? to be the oxidation number of nitrogen in dinitrogen pentoxide, ${\text{N"_color(blue)(2)"O}}_{\textcolor{red}{5}}$, you can say that

color(blue)(2) xx ? + color(red)(5) xx (-2) = 0

All you have to do now is solve for ? to find

color(blue)(2) xx ? = +10 implies ? = (+10)/2 = +5

And there you have it, nitrogen has a $+ 5$ oxidation number in dinitrogen pentoxide.