[cnv22]

I'm having trouble grasping the logic here with these provided information.



Mass Relationships of Simple Compounds of Nitrogen and Oxygen

           Compound Total Mass (g) Mass of Nitrogen (g) Mass of Oxygen (g)

Oxide A     3.28                             1.00                             2.28
Oxide B     2.14                             1.00                             1.14
Oxide C     1.57                             1.00                             0.57


Possible Molecular Formulae for Nitrogen Oxides
Assuming that:

                          Oxide C is NO            Oxide B is NO              Oxide A is NO
                       
Oxide A is                 NO4                     NO2                              NO
Oxide B is                 NO2                     NO                                N2O
Oxide C is                 NO                       N2O                              N4O


I understand the logic of the first column (Oxide C is NO), and the corresponding formulas for Oxide A and B in the second column, but I don't understand why the Nitrogen doubles in the second or doubles and quadruples in the second and third columns.

[Borek]

To be honest I have no idea what the second table is trying to say - are you sure column headings are correct?

[mjc123]

Well, it's clear that for a given mass of nitrogen, the mass of oxygen in oxides A, B and C is in the ratio 4:2:1. So the question is: what oxides fit this pattern. Columns 1, 2 and 3 all fit this pattern. From here there are two ways you could proceed. You could say that NO₄ and N₄O are unknown, so Column 2 must be the right one. Or you could actually work out the mass ratio of N and O in NO, and see which one fits. Both lead to the same answer.