Two different compounds are obtained by combining nitrogen with oxygen. The first compound results from combining 46.7 gg of NN with 53.3 gg of OO, and the second compound results from combining 17.9 gg of NN and 82.0 gg of OO. Calculate the ratio of the mass ratio of OO to NN in the second compound to the mass ratio of OO to NN in the first compound.

4.02

Explanation:

The mass ratios will be given by dividing the mass of O₂ into the mass of N₂.

So lets do our calculations:

First Compound:

53.3 g O₂ / 46.7 g N₂ = 1.14

Second Compound:

82.0 g O₂ / 17.9 g N₂ = 4.58

Ratio = 4.58 / 1.14 = 4.02

This result for all practical purposes is a whole number, and it is telling us that there are 4 times as many oxygen atoms in the second coumpound as in the first compound. This is so because the ratio we just calculated is also the ratio in mol atoms:

Ratio = [ mass O₂ / MW O2 / mass N₂ / MW N₂] 2nd compound / [mass O₂ / MW O2 / mass N₂ / MW N₂! st compound]

and the molecular weights cancel each other.

The only N and O compounds that follow this ratio are N₂O₄ and N₂O, and this question could be made in a multiple choice to match formulas.